To reveal the distribution preferences of SSR in foxtail millet genome,the study analyzed distribution regularities of SSRs among the 5'-flanking regions,the 3'-flanking regions,the extron regions and the intron regions in gene locus from foxtail millet genome using bioinformatics methods.The results showed that the relative frequency,a ratio of the frequency of a type of SSR in a certain genomic region by the frequency of this SSR in whole genome,of SSRs decreased with increasing of the distance of 5'-flanking regions from start codon,and was more than 1.50 obviously in a range from 1 bp to 700 bp.However,the relative frequency of SSRs was close to 1.00 in each of other three regions.Furthermore,with increasing of the distance of 5'-flanking regions from start codon,the relative frequency of various SSR types revealed the various changing trends,and as a whole,6 SSR types,including CCG,AG,AGG,AGGG,ACC and AGC,showed both the high frequency and the high relative frequency,and of these 6 types,the distance range(1—1 800 bp)of AG,in which its relative frequency was more than 1.50,is the maximum while that of CCG is minimal(1—200 bp).Meanwhile,in the extron regions,5 SSR types with high C/G contents,including CCG,AGG,AGC,ACG and ACC,showed both a high frequency and a high relative frequency.It was concluded that SSRs distributed preferentially in a length range from about 1—700 bp of 5'-flanking regions with 6 main specific SSR types,including CCG,AG,AGG,AGGG,ACC and AGC;on the other hand,in 3'-flanking regions,the intron regions and the extron region,distribution of SSR is close to that in genome,and however,in the extron region,a total of 5 SSR types,including CCG,AGG,AGC,ACG and ACC,are obviously specifically distributed.

Leaf color mutant is an ideal material for studying C4 photosynthesis pathway and chlorophyll metabolism mechanism.In order to study the molecular mechanism of yellow-green leaf mutation in millet,and lay a foundation for the functional study of yellow-green leaf genes and the molecular mechanism analysis of chlorophyll metabolism,a stable hereditary yellow-green leaf mutant ygl7 was identified in the ethyl methacrylate(EMS)mutant library of Changnong 35.Agronomic traits,photosynthetic pigment content and photosynthetic parameters,and chloroplast ultrastructure observation were carried out on the mutant and wild type.At the same time,genetic analysis of mutant leaf color was performed,primary mapping was performed by BSA method,fine mapping was performed by an F₂ population,and candidate genes were predicted according to functional annotation combined with RNA-Seq.The expression pattern was analyzed by qRT-PCR,and the protein interaction was verified by yeast two-hybrid experiment.The results showed that the leaves of ygl7 were obviously yellow-green at seedling stage and elongation stage,and gradually turned to light green at heading stage compared with the wild type.The chlorophyll content and photosynthetic rate of ygl7 during the whole growth stage were significantly lower than that of the wild type,and the chloroplast structure was abnormal.Genetic analysis showed that ygl7 yellow-green leaf phenotype was controlled by a pair of recessive single genes.Yellow-green leaf gene was located in the 434.9 kb region of chromosome Ⅶ.Candidate gene analysis predicted that Seita.7G290300 encoding protoporphyrin Ⅸ magnesium chelatase Ⅰ was the candidate gene for regulating yellow-green leaf.The results of qRT-PCR showed that Seita.7G290300 was highly expressed in leaves,and the expression of Seita.7G290300 in mutant was lower than that of wild type.The expression levels of genes related to chlorophyll synthesis pathway(CHLD,CHLI)and photosystem(LHCB1,LHCB6)were down-regulated in the mutants.The experiment of yeast two-hybrid showed that SiYGL7 interacted with MORF2.

In order to explore the role of RPM1 in sorghum disease resistance,a sorghum SbRPM1 gene was obtained from sorghum smut resistant variety SX44B by homologous cloning method.The bioinformatics analysis results showed that the total length of the cDNA of SbRPM1 gene was 2 802 bp,encoding 933 amino acids,and its protein had a theoretical molecular weight of 106.1 ku and an isoelectric point of 7.11,which was a hydrophilic protein.The SbRPM1 protein had no transmembrane structure,and its subcellular localization was in the cytoplasm.Conservative domain analysis showed that SbRPM1 protein contained RX-CC-like,NB-ARC and LRR domains,and belonged to CNL proteins in the NLRs family.Phylogenetic analysis showed that SbRPM1 protein was most closely related to the RPM1 protein of Miscanthus lutarioriparius.The expression pattern of SbRPM1 gene was detected by Real-time quantitative PCR,and the results showed that the expression of SbRPM1 gene was higher in leaves and inflorescence,followed by roots,and the lowest in stem.The expression of SbRPM1 gene was significantly up-regulated at 24—72 h in disease-resistant varieties after inoculation with Sporisorium reilianum pathogen,suggesting that this gene could be induced by S.reilianum and played an important role in sorghum disease resistance.In this study, the CDS sequence of the SbRPM1 gene was cloned for the first time in sorghum, and the structure, nature and expression of the gene were characterized.

To reveal the diversity characteristics of endophytic bacteria in different cultivars and organs,and clarify the correlation between endophytic bacteria community structure and host varieties,organ types and disease resistance and susceptible characteristics.Six different varieties of foxtail millet,Jigu 22,Honggu,Longgu No.11 and Xiaoqinggu,Shiliuzi and Nenxuan 16,which were resistant (susceptible) to Fusarium head blight,were selected as materials.The leaves,roots,stems,leaf sheaths and mature spikes of foxtail millet,were taken respectively.DNA was extracted for PCR amplification of 16S rDNA V3—V4 region,and Miseq library was constructed for high-throughput sequencing.Microbial diversity was analyzed by Major biological cloud platform.There were certain differences in endophyte species composition between susceptible and resistant varieties,the dominant populations of endophytes were Proteobacteria and Actinobacteriota,followed by Bacteroidota and Firmicutes,Myxococota and Chloroflexi were lower relative abundance followed by Gemmatimondota and Fusobacteriota.Alpha diversity analysis showed that the resistant cultivars had higher panicle community richness at leaf and maturity spikes and higher panicle diversity at leaf,root and maturity spikes.The susceptible varieties had higher richness of root and stem community and higher diversity of stem and leaf sheath;PCoA analysis showed that organ type had more effect on endophytic community structure than variety.Species composition analysis showed that the diversity of endophytic flora in foxtail millet was affected by different varieties and different parts,and the species of endophytic flora in different parts were quite different.The diversity of endophytic flora between susceptible cultivars Xiaoqinggu,Shiliuzi and Nenxuan 16 and resistant cultivars Jigu 22,Honggu and Longgu No.11 was quite different.The resistant cultivars had NB1-j in leaf sheath stage,and the ears had Acidobacteriota in mature stage.The study showed that the diversity and community structure of endophytic bacteria were affected by different organs and varieties of the foxtail millet,and the organ types had more influence on the community structure of endophytic bacteria than varieties.

In order to screen chemical control agents that can effectively reduce millet plant height and improve its lodging resistance,as well as the optimal spraying period,and explore the effects of different chemical control agents on millet growth,development,and yield,four chemical control agents (paclobutrazol,Menthylamine,cynanchon,and uniconazole)were sprayed on Nenxuan 17 during the seedling and jointing stages.The dry matter accumulation, SPAD, net photosynthetic rate, stem characteristics and yield components of each treatment plant were measured during the filling and mature stages.The results showed that spraying uniconazole,chlorpyrifos,chlorpyrifos,and paclobutrazol during the seedling and jointing stages of foxtail millet could dwarf plants to varying degrees,increase stem diameter,improve lodging resistance,and achieve yield increase.Among them,the plant height and internode length of foxtail millet decreased by 6.76% and 25.43% respectively compared to CK during the seedling stage.Spraying chloramphenicol had the most significant effect on increasing stem diameter during the seedling stage,which was 22.89% higher than CK.The foxtail millet had the best lodging resistance under the spraying of foxtail millet,and the spraying of foxtail millet had the most significant effect on increasing yield during the seedling stage,which was 17.51% higher than CK;all four regulators could significantly increase the SPAD value and net photosynthetic rate of millet leaves.Spraying paclobutrazol at the seedling stage had the best effect on improving the SPAD value and net photosynthetic rate,with an increase of 35.29% and 30.37% respectively compared to CK;spraying chemical control agents had no significant effect on the accumulation of aboveground dry matter in millet plants compared to CK.Overall,spraying paclobutrazol during the seedling stage had the best effect and could be applied as a suitable chemical control and lodging resistance measure for high-yield cultivation of millet.

To scientifically and accurately identify foxtail millet germplasm resources,strengthen the management of millet germplasm resources and protect new varieties.33 pairs of SSR markers were selected to establish molecular identity cards for 94 foxtail millet germplasm resources.A total of 500 SSR markers covering 9 linkage groups of foxtail millet chromosomes were screened,of which 33 markers showed polymorphic bands and stable amplification,these markers were used to establish molecular ID of 94 foxtail millet varieties.A total of 203 polymorphic bands were obtained.The number of alleles revealed by each marker was 3—10 with an average of 6.2.The polymorphism information content(PIC)values for the SSR loci ranged from 0.429 to 0.864 with an average of 0.740.Ten markers,including b185,b260,b224,b103,b225,CAAS1044,b186,b253,b105 and CAAS3008,were identified to be efficient in the variety ID construction.The IDs of 94 foxtail millet varieties were established by the 10 pairs of markers,which could clear distinguish all the varieties tested.

Ideal plant architecture can significantly improve crop yield,but the relationship between plant architecture traits and yield traits is still unclear in foxtail millet.To provide a theoretical basis and germplasm resource for plant architecture breeding in foxtail millet,10 plant architectures traits(plant height,main stem length,panicle length,panicle neck length,panicle diameter,tiller number,node number,length of flag leaf,width of flag leaf and area of flag leaf)and 3 yield traits(panicle weight,panicle grain weight and 1000-grain weight)were analyzed via 126 F₆ recombinant inbred lines(RIL)from a F₁ arrived from a cross between Aininghuang and Jingu 21 under three ecological environment consisting of Changzhi,Yuci and Datong.Based on the best linear unbiased estimation(BLUE),variance analysis,correlation analysis,partial correlation analysis,principal component analysis,multiple regression analysis and cluster analysis were conducted.The phenotype variation analysis showed there were an extremely significant difference between plant height and main stem length in three ecological environments,a significantly or extremely significant difference between panicle neck length and node number in two ecological environments,and the significant or extremely significant differences among panicle length,panicle diameter,panicle weight,panicle grain weight and tiller number in single ecological environment.In RIL population, an abundant variation was observed for 13 traits with the approximately normal frequency distribution,and the variation coefficients ranged from 6.86% to 31.71%.Except for the main stem length in Yuci, other traits showed a transgressive separation in three ecological environments.Correlation analysis and partial correlation analysis indicated that panicle weight and panicle grain weight were extremely significant positive correlated with plant height,main stem length,panicle length,panicle neck length and node number,while they were extremely significant negative correlated with tiller number,panicle weight was significantly positive correlated with flag leaf length.Principal component analysis simplified 13 traits into 4 principal components,and the cumulative contribution rate was up to 93.938%.The fitting degree R² of multiple regression analysis was 0.614, and main stem length,panicle length and tiller number were the main factors affecting panicle weight.The RIL population was divided into 7 groups via cluster analysis,among which Group Ⅴ consisted of 3 materials with the highest yield, medium plant height and good comprehensive traits,which could be used as elite parents for ideal plant architecture breeding.

In order to alleviate continuous cropping obstacles and improve soil, to ensure sorghum raw grain production and sustainable agricultural development. The long-term located experiment of continuous cropping sorghum was carried out in Dongbai base of Sorghum Research Institute of Shanxi Agricultural University from 2019 to 2020 to study the effects of tillage methods(traditional tillage,no tillage,rotary in autumn,subsoiling in autumn,deep ploughing in autumn,deep ploughing in spring)in fallow period on soil moisture,organic carbon content and yield of continuous cropping sorghum,aiming to find the suitable tillage method and time for increasing the yield of continuous cropping sorghum,and the mechanism of water conservation,carbon sequestration and yield increase so as to provide cultivation techniques and theoretical basis for the stable production of sorghum.The results showed that tillage in fallow period increased the soil organic matter in 0-20 cm soil layer in each growth period of sorghum,and increased the content of particulate organic carbon,light fraction organic carbon,heavy fraction organic carbon,readily oxidized organic carbon and dissolved organic carbon, and also increased soil water storage in 0-100 cm soil layer by 0.72-46.52 mm before sowing and soil water storage of 0-100 cm soil layer at each growth period, furthermore, the soil water before sowing continued to be used until jointing stage and it still was very effective even though much precipitation in the middle and late stages.Meanwhile,tillage in fallow period increased the yield by 4.75%-23.67% and the water use efficiency in the growth period by 19.09-29.19 kg/(ha·mm),especially the increased effect of deep ploughing in autumn was more significant.The correlation analysis showed that the yield of continuous cropping sorghum was significantly positively correlated with soil moisture and organic matter content,and the yield was more closely related to the soil moisture in the early growth stage if the base soil moisture level was higher and more closely related to the soil moisture in the middle and late stages if the base soil moisture level was lower and the precipitation in the middle and late stages was more.In short,deep ploughing in autumn of continuous cropping sorghum during fallow period was beneficial to increase the organic carbon content and promote the soil moisture conservation so that the moisture continued to be used at jointing stage,thereby increased yield and water use efficiency.

Tiller higher than main stem is one of the important reasons that make the uniformity of sorghum varieties and mechanized production of sorghum complicated.In order to clarify the mechanism of the gene that regulates the tiller height in sorghum,improve the uniformity of sorghum varieties and breed sorghum varieties suitable for mechanized production,based on the mapping results of our previous studies,15 of the sorghum variety whose tiller height was consistent with main stem height as well as 17 of the sorghum variety whose tiller height was higher than main stem height,were selected to form the natural population to have the candidate genes tested.It was found that it was the SNP3 locus belonging to the gene Sobic.009G2133001.v3.2 located in the conserved domains of Hydrolase_4 affects the tiller height,it was named SbTH.With two sorghum varieties K35-Y5 and 1383 taken as material,the expression patterns of gene SbTH in different sorghum tissues were analyzed by Real-time fluorescence quantitative PCR.The results showed that the SbTH gene got expressed in both the roots and the leaves.Though the expression levels were different,the trends were basically the same.In the stem of variety 1383 whose tiller was higher than main stem,the expression level and trend were almost the same.Only in variety K35-Y5 whose tiller height was consistent with main stem height,at anthesis of main stem,reverse expression pattern was observed.While the expression level of main stem reached the maximum,the expression level of tiller was lowered to the minimum.From above results,we concluded that the expression level of SbTH was low in the tiller of K35-Y5,thus the overgrowth of the tiller internodes got controlled,forming the plant phenotype whose stem and tiller had the same height.The expression level of SbTH was high in the tiller of variety 1383,thus the growth of tiller internodes was promoted,which made the tiller be higher than the stem.Therefore,it is believed that the differential expression of gene SbTH at anthesis of main stem is the key to tiller height regulation.

WRKY transcription factors act important regulators in plant response to low phosphorus.Buckwheat performs well in under-fertilized soils with higher phosphorus use efficiency.Taking tartary buckwheat as experimental materials,this study aims to explore the possible regulatory roles of WRKY genes in phosphorus starvation response of buckwheat.The entire coding sequence(CDS)of FtWRKY6 gene was cloned from RNA samples generated from roots treated by low phosphorus using reverse transcription PCR.The obtained CDS of FtWRKY6 was 1 572 bp in length,encoded a polypeptide of 524 amino acid residues which consists of two conserved WRKY domain each with a zinc finger motif of CCHH,and belonged to the WRKY group Ⅰ.FtWRKY6 shared the highest identity(55.5%)at the amino acid level with Camellia sinensis CsWRKY24.Transient expression assay in protoplasts showed that FtWRKY6 protein was localized in nucleus.Yeast one-hybrid assay revealed that FtWRKY6 had transcription-activating activity.Real-time fluorescence quantitative PCR analysis showed that the expression of FtWRKY6 in roots was significantly induced by low phosphorus and three related hormones such as indole acetic acid(IAA),gibberellin(GA)and cytokinin(CTK).Taken together,FtWRKY6 possesses basic structural and biochemical characteristics as a putative transcription factor,and may be involved in low phosphorus response in roots possibly by crosstalk of IAA,GA and CTK signaling pathways.

In order to elucidate the effect of decreasing nitrogen rate and increasing planting density on photosynthesis,dry matter accumulation and transportation characteristics and yield of sorghum,a field experiment was conducted using the waxy sorghum hybrid Jinyunuo 3 as experimental material in 2017-2018.Four treatments of normal nitrogen application with normal planting density(CK),normal nitrogen application with dense planting density(T1),reducing nitrogen application with normal planting density(T2),and reducing nitrogen application with dense planting density(T3)were set to investigate the chlorophyll content(SPAD)and leaf area index(LAI)at heading stage,dry matter accumulation and transport characteristics,yield and yield components of sorghum. The results showed that,compared with CK,the SPAD of the top three leaves at heading stage and LAI were decreased by reducing nitrogen application,while the SPAD was decreased by dense planting,but LAI was increased significantly.The dry matter accumulation of sorghum population increased with the development of growth process and increased rapidly after jointing stage and reached the maximum in maturity stage.Reducing nitrogen application improved dry matter translocation efficiency of leaf and stem+sheath before anthesis and contribution to grain,but decreased dry matter accumulation of population,dry matter accumulation after anthesis and its contribution to grain.Increasing density significantly boosted dry matter accumulation of population,dry matter translocation of leaf and stem+sheath before anthesis,as well as their transportation efficiency and contribution to grain,but reduced the contribution of dry matter to grain after anthesis. The ear weight and 1000-grain weight were reduced by dense planting,but the yield increased significantly. The ear weight and 1000-grain weight were decreased by reducing nitrogen application,but the yield of normal density decreased while that of densification increased significantly. Compared with CK,the 2-year average yield of T1 and T3 treatments were significantly higher by 8.43% and 7.92% respectively,and there was no significant difference between the two treatments. In conclusion,the planting mode of Jinyunuo 3 in Chongqing was reducing nitrogen application with dense planting,that was,applying nitrogen 150 kg/ha and density 12.75×10⁸ plants/ha. It was beneficial to realize high yield,high efficiency and nitrogen saving cultivation of sorghum.

In order to explore the changes of physiological characteristics and genetic materials of naked oats during storage, the germination rate, germination potential, malondialdehyde(MDA)content, peroxidase dismutase(SOD)activity, catalase(CAT)activity, peroxidase(POD)activity and polyphenol oxidase(PPO)activity of naked oats seeds with different storage years were measured. The number of cells with genetic material distortion was counted by microscopic examination.The results showed that the germination rate and germination potential of naked oats seeds decreased with the extension of storage years.After storage for 8 years,Bayou 1 decreased by 86.42 and 96.92 percentage points;the content of MDA in naked oats seeds increased with the extension of storage years,and the maximum increase of Jinyan 8 was 5.68 times;the activities of SOD,CAT,POD and PPO of naked oats seeds decreased with the extension of storage years.After 8 years of storage,Bayou 1 decreased the most,which were 84.66%,74.38%,54.09% and 81.44% respectively;the number of cells with genetic material distortion in naked oats increased with the extension of storage years,and the average increase of the three varieties for 8 years was 11.87 times.The germination rate was significantly correlated with MDA content,SOD activity,CAT activity,POD activity,PPO activity and the number of aberrant cells(P<0.01),and the number of aberrant cells was significantly correlated with MDA content,SOD activity,CAT activity,POD activity and PPO activity(P<0.01).Bayou 1 had the best storage resistance,Jinyan 17 was the second,and Jinyan 8 was the worst.The germination rate and germination potential of naked oats decreased with the extension of storage years,the activities of SOD,CAT,POD and PPO decreased with the extension of storage years,and the content of MDA and the number of distorted cells increased with the extension of storage years;SOD,CAT and POD activities are essential enzymes for seed survival,but not the key enzymes for seed germination.

In order to clarify the characteristics of the endophytic bacterial community of different varieties of foxtail millet,reveal the key species related to foxtail millet downy mildew resistance.DNA extraction was performed on the lowest node stem and the highest node stem tissues of 3 kinds of foxtail millet downy mildew-resistant and 3 kinds of foxtail millet downy mildew-susceptible foxtail millet plants.We used Illumina Miseq to sequence the bacterial 16S rDNA of the samples and analyzed the susceptible community composition of endophytic bacteria.The results showed that at each classification level,the endophytic bacterial species from the lowest node stem to the highest node stem showed two different trends in disease-resistant and susceptible foxtail millet samples,which were basically stable and significantly decreased.And the species composition of the endophytic bacterial community in disease-resistant foxtail millet was more abundant than that of susceptible foxtail millet.19 important endophytic bacteria phyla were obtained:(from the comparison of the endophytic bacteria ubiquitous in the lowest node stem of disease-resistant and susceptible foxtail millet samples were obtained) 2 species of endophytic bacteria phyla specific to disease-resistant foxtail millet;(from the comparison of all endophytic bacteria of disease-resistant and susceptible foxtail millet samples 16 species of endophytic bacteria phyla unique to disease-resistant foxtail millet and 2 dominant groups with relatively large abundance of disease-resistant foxtail millet were obtained).It can be seen that the endophytic bacterial communities in different foxtail millet varieties and different parts are different,and the endophytic bacterial species of disease resistance are more abundant than that of susceptible foxtail millet.Among them,the endophytic bacteria phyla unique to disease-resistant foxtail millet materials and the dominant endophytic bacteria phyla with relatively large abundance may have an effect on the prevention and treatment of foxtail millet downy mildew,which is worthy of further study.

In order to understand the function of SibHLH19 in foxtail millet,the CDS sequence and promoter sequence of SibHLH19 gene were separately cloned with the leaf cDNA and genomic DNA from resistance material Shilixiang as template by PCR.Promoter cis-acting elements and biological characteristics were analyzed using bioinformatics online tools.Then the expression patterns of SibHLH19 in different tissues and during the process to rust resistance were surveyed by qRT-PCR,respectively.Lastly the prokaryotic expression characteristics for the gene were detected by SDS-PAGE,laying a theoretical foundation for further research on SibHLH19 gene function and disease resistance mechanism.The results showed that the CDS sequence of the SibHLH19 transcription factor was 843 bp in length,encoding a total of 280 amino acids,the predicted protein molecular weight was 29.97 ku.The theoretical isoelectric point was 5.85,and the encoded protein chemical formula was C₁₂₉₆H₂₀₇₁N₃₉₇O₄₀₀S₁₁,containing a bHLH conserved domain,belonging unstable hydrophilic protein.The largest element of the protein's secondary structure was random coils,and the smallest element was a β-turn.Evolutionary analysis showed that SibHLH19 had the higher homology to the amino acid sequences of Panicum miliaceum (RLM85279.1),Panicum hallii (PUZ71581.1)and Panicum virgatum (XP_039835205.1),and had the lowest homology with Triticum aestivum(KAF7059972.1)and Aegilops tauschii subsp.strangulata (XP_040244423.1).The analysis of the promoter cis-acting elements showed that there were multiple response elements such as hormones and stresses in the promoter region of the SibHLH19 gene.Tissue expression analysis showed that the gene was mainly expressed at the seedling stage with the highest expression in the aboveground part,and was almost no expression at the booting stage.Within 24 hours of the response to the biotic stress of rust disease in foxtail millet,the SibHLH19 gene expression was up-regulated at 8 and 16 h in the disease resistance response,while its expression was only slightly up-regulated at 16 h and down-regulated at the rest of the time points in the susceptible response.It was speculated that SibHLH19 played a positive regulatory role in the resistance response to rust disease in foxtail millet.The constructed prokaryotic expression vector pET30a-SibHLH19 could express the SibHLH19 fusion protein with an apparent molecular weight of about 44 ku after being induced by 0.1 mmol/L IPTG.

In order to explore the effective methods for the identification of drought tolerance of foxtail millet during the entire growth period,select the identification indices of drought tolerance of foxtail millet,and speed up the process of drought tolerance breeding of foxtail millet,a field experiment was conducted using a randomized incomplete block design(alpha-lattice design)and repeated thrice in 2019—2020. Each experiment consisted of 30 foxtail millet genotypes treated under drought stress(DS)and normal water supply(CK). The agronomic traits and drought tolerance coefficient(DC)of the genotypes were assessed during the entire growth period. Combined analysis of variance showed that soil water environment had significant effects on 1000-grain weight,and extremely significant effects on the other indices. Genotype had significant effects on spike weight and grain weight per plant,and extremely significant effects on the other indices. Besides,the interaction between genotype and soil water environment extremely significantly affected the growth traits of foxtail millet,but not yield traits(except 1000-grain weight). Under drought stress,the characteristic value of each index decreased in varying degrees compared with CK,and the sensitivity of each index to drought stress was different. The results of t test showed that the effect of drought stress was significant(except 1000-grain weight). GGE biplot explained 71.15% of the total variation of data.The drought tolerance coefficient of each index was correlated in different degrees,in which the drought tolerance coefficients of plant height,spike length,stem and leaf dry weight and top second leaf area were significant positive correlation,and that of spike weight per plant,grain weight per plant,kernels per spike and yield were also significant positive correlation. The drought tolerance of foxtail millet could be reflected by different agronomic traits. According to the distance from ideal drought-tolerant varieties and ideal drought-tolerant evaluation indices,the drought tolerance and evaluation indices of foxtail millet materials were ranked. Taixuan 26,Chaogu 62,Chaogu 13 and other materials had strong drought resistance,plant height and spike weight per plant could be used as indices for drought tolerance identification in foxtail millet. GGE biplot provided an objective and effective new visual identification method for the breeding of drought resistant foxtail millet varieties.

In order to reveal the diversity characteristics of endophytes in different species and different organs,the correlation between endophyte community structure and host species and organ types was preliminarily clarified.The stems,leaves and leaf sheaths,which were respectively collected from the plants of the foxtail millet blast-susceptible varieties Shawan millet and Jigu 22 and the foxtail millet blast resistant varieties Xiaoqinggu and Shiliuzi,were used to carry out the endophytic diversity by high-throughput sequencing based on the 16S rDNA V3—V4 region.There were certain differences in endophyte species composition between susceptible and resistant varieties.In all tested samples,the dominant groups at the phylum level were Proteobacteria and Actinobacteriota.Bacteroidota,Chloroflexi,Myxococcota,Firmicutes followed.Alpha diversity analysis showed that the susceptible varieties(Shawan millet,Jigu 22)had higher abundance of endophyte in leaves.PCoA analysis revealed that the organ type had a greater impact on the endophyte community structure than the variety.Species composition analysis showed that the susceptible varieties Shawan millet and Jigu 22 contained endophytic flora that were significantly different from those of Xiaoqinggu and pomegranate(resistant to foxtail millet blast).The susceptible varieties(Shawan millet,Jigu 22)contained Entotheonellaeota phylum in leaves,while resistant varieties had Hydrogenedentes phylum in leaf sheaths.It clarified that the diversity and community structure of endophytes in different organs and millet varieties susceptible and resistant to foxtail millet blast were different,and organ types had a greater impact on the community structure of endophytes than varieties.

The SiPRR73 gene was cloned from Yangu 11 using RT-PCR technology,and through analyzing tissue-specific expression,responsive features of SiPRR73 to different photoperiods,photo-thermal combinational treatments and five abiotic stress treatments,the regulation mode of photoperiod and temperature on SiPRR73,and the responsive pattern of SiPRR73 to abiotic stresses in foxtail millet were explored. The results showed that totally 2 928 bp cDNA sequence of SiPRR73 was obtained from Yangu 11,which included 2 283 bp CDS region,encoding 760 amino acids. The SiPRR73 proteins of C4 crops including Panicum miliaceum,Panicum hallii,Sorghum bicolor and Zea mays showed relatively close relationship with SiPRR73. The second parietal leaf was the highest expression tissue of SiPRR73,but the expression level at root,stem and panicle tissues was relatively lower. The expression level of SiPRR73 was higher at light period than that at dark period under both short-day and long-day conditions,and during the whole vegetative growth phase,SiPRR73 showed higher expression level under long-day compared to short-day,which indicated that the expression of SiPRR73 was induced by light and controlled by photoperiod. The temperature determined expression peak number of SiPRR73 and the photoperiod determined occurrence time of expression peaks,so temperature and photoperiod participated in regulating of SiPRR73 expression mutually. PEG and low temperature stresses induced SiPRR73 expression totally,NaCl induced SiPRR73 expression at early stress stage,but inhibited it at later stress stage. Fe stress inhibited SiPRR73 expression at early stage,but induced it at later stage. ABA stress caused the close responsive feature of SiPRR73 to NaCl. This study indicated that SiPRR73 showed light-dependent expression feature,and photoperiod and temperature regulated SiPRR73 by interaction pattern,suggesting that SiPRR73 participated in adaptability regulation process to different photo-thermal conditions and might play a certain role in coping with drought,low temperature,ABA,NaCl and Fe stresses in foxtail millet.

In order to alleviate the continuous cropping obstacle of millet,provide a reference for optimizing millet planting mode,millet continuous cropping(Si)was named as control(CK),millet-corn(Si-Zm),millet-potato-corn(Si-St-Zm),millet-corn-soybean(Si-Zm-Gm)and millet-soybean-potato(Si-Gm-St)were used to analyze the effects of different rotation patterns on the physiological indicators,photosynthetic characteristics,agronomic characters,yield and downy mildew incidence rate during the critical millet growth periods.The results showed that compared with CK,in the Si-St-Zm,Si-Zm-Gm and Si-Gm-St rotation patterns,the activeness of superoxide dismutase,peroxidase and polyphenol oxidase in millet flag leaves were significantly increased,with the largest increases of 45.55%,41.55% and 109.09%,respectively.In the Si-Zm-Gm and Si-Gm-St rotation patterns,millet plant height,stem thickness,root length and root branch number were significantly increased,with the largest increases of 30.48%,30.50%,31.76% and 13.79%, respectively.In addition,compared with CK,under the Si-Gm-St rotation system,the H₂O₂ and MDA content in the millet flag leaves were significantly decreased,with the maximum reductions of 18.78% and 47.29%, respectively;and the stomatal conductance,net photosynthetic rate,transpiration rate and relative chlorophyll content were significantly improved by 31.94%-101.43%,35.74%-234.00%,16.44%-46.97% and 24.15%-66.16%,respectively;with millet ear length,1000-grain weight and yield increased by 14.90%,17.09% and 10.58%,respectively;and millet downy mildew incidence rate significantly reduced by 12.33%.In short,compared with CK,the Si-Gm-St rotation system significantly increased the activeness of SOD,POD and PPO,and improved photosynthetic efficiency in millet flag leaves,meanwhile,the millet yield and disease resistance enhanced.Therefore,compared with Si-Zm,Si-St-Zm and Si-Zm-Gm rotation patterns,Si-Gm-St rotation system has the best effect on alleviating continuous cropping obstacles,which can provide a reference for optimizing millet planting system.

To study the decomposition characteristics of sorghum and maize residues and the functional diversity of microbial community in straw decomposition,under different residual types(sorghum stalk-leaves,maize stalk-leaves,sorghum root,maize root),soil type(cinnamon soil,yellow loam soil),nitrogen treatment(adjust C/N ratio,not adjusted),the culture experiment method was used to explore the decomposition characteristics of residues under different decomposition conditions,and to analyse the metabolic functional diversity of microbial community used the BIOLOG-ECO plates method in straw decomposition process.The results showed that the decomposition rate of sorghum and maize residues was faster in the early stage than the late stage.The residual dry matter degradation rate and CO₂ release rate had the following pattern of decomposition rate was shown,sorghum stalk-leaves>maize stalk-leaves>sorghum root>maize root,under the same soil and nitrogen treatment.According to the second experiment, the dry matter degradation rates of sorghum stalk-leaves and maize stalk-leaves were 55.50% and 48.00%,respectively,however,the dry matter degradation rate of sorghum root and maize root were 31.25% and 16.75%,respectively at 60 d of incubation,under the condition of cinnamon soil+N treatment.The degradation rate of hemicellulose and cellulose in root were lower than that in stalk-leaves,under the same soil and N treatment conditions,the decomposition of hemicelluloses and cellulose was decreased by 23.70,18.80 percentage point,in sorghum root treatment than sorghum stalk-leaves treatment at 90 d of incubation,under the condition of cinnamon soil+N treatment.The microbial metabolic activity of straw was the highest at 30 d and lowest at 90 d during decomposition.The metabolizable ability of microbial community of straw decomposition to amines and phenolic acids was lower on the 1st day of decomposition,and the metabolizable ability to carbohydrates,amino acids and polymers was significantly decreased on the 90th day,compared with 30 d.Collectively,the decomposition of sorghum residues was easier than maize,and adjusting C/N ratio could accelerate the decomposition of residue to a certain extent.The microbial metabolic diversity was the highest at 30 d under the experimental conditions.

In order to clarify the difference of yield and nitrogen use efficiency between new and old generations of waxy sorghum varieties(lines)in Guizhou, the sorghum cultivars of HYZ, QG8H, HongKN and HeiKN were used as experimental materials, two nitrogen treatments(LN and HN)were set up.The differenceof yield, nitrogen accumulation and nitrogen use characteristics of which were analyzed by split plot design. The results showed that:the yield, dry matter and nitrogen accumulation of 2010s cultivars(HYZ and QG8H)were significantly increased by 25.4%, 25.1% and 33.3%, respectively, compared with those of 1990s cultivars(HeiKN and HongKN). NHI under LN treatment was significantly different among cultivars, but not under HN treatment. Compared with LN, RNAP of 1990s cultivars decreased significantly under HN treatment, with a range of 20.9%, which indicated that the 2010s cultivar had a stronger post-flowering N assimilation capacity, and a stronger grain N accumulation capacity at both low and high N levels.NPFP, NARR, NRE and NFAE of 2010s cultivars were increased by 13.9 kg/kg, 0.7 kg/kg, 20.3% and 4.1 kg/kg, respectively, compared with the 1990s cultivars. Yield, DMA, TNA were significantly positively correlated with NRE, which indicated that the increased yield of waxy sorghum in Guizhou Province might relate to the increase of nitrogen accumulation caused by the improvement of NRE, which provided sufficient nitrogen supply for the normal physiological metabolism of waxy sorghum.

In order to reveal the possible functional effects of SiCCT gene, and provide foundation for further research of the function of SiCCT gene in photo-thermal interaction-controlled flowering process of foxtail millet, the photoperiod sensitive millet variety Huangmaogu was used as experimental material to analyze the diurnal expression patterns of SiCCT gene under long-day and high temperature(LD, 27℃), long-day and low temperature(LD, 22℃), short-day and high temperature(SD, 27℃), short-day and low temperature(SD, 22℃), totally four photo-thermal combinational conditions by fluorescence quantitative PCR. Furthermore, based on the survey data of ten main agronomic traits for two consecutive years, candidate gene-based association analysis was performed. The results showed that the expression of SiCCT gene was not affected by temperature, and the expression level of SiCCT gene under long-day was wholly higher than that under short-day at light period. While at darkness period, the expression of SiCCT gene was affected by temperature, especially under short-day, the expression level of SiCCT gene at low temperature was obviously higher than that at high temperature. Based on the association analysis of candidate gene, it was found that 11 polymorphic loci detected in SiCCT gene were significantly associated with 8 major agronomic traits(P <0.05), among which, SNP-10 was associated with heading stage, leaf number and grain weight per panicle at Luoyang, Henan and Jilin, Jilin, SNP-100 and SNP-104 were associated with plant height, leaf number and panicle length at Luoyang. SNP-51 was detected at Ledong of Hainan, Luoyang and Jilin for two consecutive years, but the related traits were different, which were ear diameter, branch number per panicle and leaf number at Ledong, Luoyang and Jilin, respectively.The expression of SiCCT gene was controlled by photoperiod, and temperature also affected its expression at darkness period under short-day. SiCCT gene possessed pleiotropic effects, but its function was regulated by photoperiod condition.

In order to study the tolerance of heterologously overexpressed Atvip1 gene in sorghum to defense saline-alkali stress and the corresponding growth, NaHCO₃:Na₂CO₃ of 5:1 solution with 75 mmol/L and pH 9.63 was used in sorghum at the stage of three leaves and one heart. The root growth index, chlorophyll content, antioxidant enzyme activity and MDA content were measured at 0, 4, 12, 24, 72, and 120 h of stress. The results indicated that the heterologous overexpression of Atvip1 gene could alleviate the damage of saline-alkali stress on the growth of sorghum seedlings, increase the root surface area and root volume, the number of root tips and branches, and also cause the browning of sorghum main roots to appear later and mild symphonys, and the earlier and more lateral roots occurrence. The new leaves could still be normally extended at 72 h and present little effect on the growth of aboveground. Overexpression of Atvip1 gene could increase the activity of O₂^-· resistance, decrease the content of MDA and enhance the activities of antioxidant enzymes in transgenic sorghum roots. SOD, CAT and GR had obvious effects at 4-12 h during the early stage of stress, respectively. All enzymes played roles during the middle of stress at 24-72 h. CAT and GSH-PX played important roles at the later stage of stress at 120 h. On the base of differential transcriptome analysis of saline-alkali stress, COG analysis of differentially expressed genes(DEGs) showed that defense mechanisms accounted for a relatively large proportion during various periods, and 42 DEGs related to antioxidant enzymes were obtained. Heterologous overexpression of Atvip1 gene can improve the resistance of transgenic sorghum to saline-alkali stress by alleviating the effects on photosynthesis, growth and development, reducing the damages of reactive oxygen species and membrane damage.

In order to study the physiological response and difference of nitrogen metabolizing enzyme activity in leaves of different forage oats in Horqin Sandy Land. The forage oats of Muwang and Tianyan No.1 were applied with 0 (CK), 100, 200, 300 kg/ha pure nitrogen in the proportion of 15%, 40%, 25% and 20% at tillering, jointing, heading and flowering stages. The activities of glutamate synthase (GOGAT), glutamine synthetase (GS), nitrate reductase (NR), glutamic oxaloacetic transaminase (GOT), glutamic pyruvate transaminase (GPT) were measured in flag leaf, inverted two leaf and converse third leaf during the filling period, and the differences of nitrogen metabolizing enzyme activities and their relationship with hay yield of different forage oat varieties under nitrogen application rate were analyzed. The results showed that the hay yield of Muwang and Tianyan No.1 reached the maximum at 200,300 kg/ha nitrogen levels, respectively;The activities of GOGAT, GS, NR, GOT and GPT in the leaves of Muwang and Tianyan No.1 forage oats increased first and then decreased with the increase of nitrogen application, and the enzyme activity was the strongest under N₂₀₀ nitrogen application (except for GOT activity of converse third leaf under N₃₀₀ treatment).Except for GS activity of the third leaf of N₁₀₀ treatment and GPT activity of the second leaf in different nitrogen treatments, GOGAT, NR, GS, GOT and GPT enzyme activities of Muwang were higher than those of Tianyan No.1. This indicated that nitrogen assimilation ability of forage oat variety Muwang was stronger than that of Tianyan No.1.Therefore, in Horqin Sandy Land, the suitable amount of topdressing nitrogen fertilizer for planting Muwang was 200 kg/ha, while for planting Tianyan No.1, topdressing nitrogen fertilizer of 300 kg/ha could obtain higher hay yield. GOT and GPT activities were the key enzymes for screening forage oat varieties with high nitrogen use efficiency.

The purpose of this study was to reveal the intercropping advantage of sorghum-soybean intercropping system. Field experiments were conducted in 2018 and 2019 in Fenyang of Shanxi Province. This study included nine treatments, sole-higher sorghum Jinza 22 (G1), sole-lower sorghum Jinza 34 (G2), sole-soy bean(D), 2 rows sorghum and 2 rows soybean(2G1:2D, 2G2:2D), 2 rows sorghum and 3 rows soybean(2G1:3D, 2G2:3D), 2 rows sorghum and 4 rows soybean (2G1:4D, 2G2:4D). Sorghum and soybean yield, land equivalent ratio, water and nutrient use efficiency of different sorghum-soybean intercropping treatments were investigated. The results showed that the 1 000-grain weight and spike weight of sorghum in intercropping system were no significant difference than that of sole sorghum. However, the pods number of soybean had significant difference between different treatments. Compared with sole-soybean(D), the pods number of soybean in 2G1:2D, 2G2:2D, 2G1:4D, 2G2:4D decreased by 37.89%, 32.16%, 22.46%, 21.51%, respectively. The land equivalent ratio (LER) and water equivalent ratio (WER) in the all intercropping system were more than 1, indicating that there were some advantages in land and water use. The nutrient advantage of intercropping system was due largely to a higher total nitrogen accumulation than that of the sole system. Compared with 2G2:2D, the average LER, WER, total nitrogen accumulation of 2G1:2D increased by 8.91%, 8.30%, 4.56%, respectively.The average LER, WER, total nitrogen accumulation of 2G1:4D increased by 10.17%, 9.14%, 4.35%, respectively, than that of 2G2:4D. In the sorghum Jinza 22 and soybean intercropping system, the LER, WER, total nitrogen, phosphorus and potassium accumulation of 2G1:4D were the highest among the intercropping treatments. In conclusion, the LER, water and nitrogen use efficiency by sorghum-soybean intercropping could be improved, and the intercropping advantages of higher sorghum Jinza 22 and soybean were more obvious than that of lower sorghum Jinza 34 and soybean, and the 2G1:4D intercropping system was the suitable combination under the experimental condition.

In order to clarify the change rule of photosynthetic characteristics and the best fertilization method in different growth stages of sweet sorghum under different fertilization treatments, the field experiment was conducted to study the stomatal conductance (Gs), intercellular CO₂ concentration (Ci), transpiration rate (Tr), net photosynthetic rate (Pn), chlorophyll (SPAD), water use efficiency (WUE) and yield of New Sorghum No.3 under 8 different fertilization treatments, including CK, NK, NP, PK, NPK, M (organic fertilizer), NPKM and 1.5NPKM.The results showed that the changes of Pn, Gs, WUE and SPAD value in sorghum leaves under different fertilization treatments were the same at different growth stages, showing a trend of first increasing and then decreasing, and peaking at grain filling stage. The variation trend of Tr and Ci from flowering stage to maturity stage decreased first and then increased, and reached the lowest value in grain filling stage. At the same growth stage, the photosynthetic characteristics of different fertilization treatments were different, and the photosynthetic characteristics of leaves were affected by fertilization treatments. The Tr, Gs and Ci values of NPKM fertilization treatment at maturity stage were higher than those of other treatments, which were 3.64 mmol/(m²·s),328 mmol/(m²·s),439 μmol/mol, respectively. The correlation analysis showed that Pn of NPKM treatment at flowering stage was significant positively correlated with Tr and WUE, while Pn of NPK treatment was positively correlated with Gs and Ci. The biological yield of all fertilization treatments was significantly higher than CK, among them the biological yield of NPKM treatment reached 94.81 t/ha. The biological yield of NPKM increased 97.95%, 26.65%, 20.24%, 19.57%, 15.16%,14.98% and 11.74% respectively compared with CK, M, 1.5 NPKM, NK, PK, NPK and NP. Fertilization affects the photosynthetic parameters of the leaves of New Sorghum No.3 and was conducive to increasing yield. Therefore, it is feasible to use high photosynthetic efficiency breeding to improve biological yield. In order to alleviate the obstacle of continuous cropping of sweet sorghum, different proportion of fertilizer should be adopted. In a word, NPKM is the best fertilization mode to improve photosynthetic conditions and maximize yield, so it is preliminarily confirmed that NPKM is the best fertilization mode to promote the growth and development of continuous cropping sorghum in arid area.

In order to clarify the continuous cropping barrier mechanism under the condition of large-scale cropping of millet in mountainous areas,representative soil samples were collected from 0-3 years of continuous cropping in Huangqi of Fengning County and Xichengshui of Lincheng County.Through the determination and analysis of the content of total nitrogen,available phosphorus and available potassium,soil pH value,stress-resistance activity of millet plants,and microbial community species and abundance in the soil,the mechanism of continuous cropping obstacle was preliminarily revealed from the physiological and pathological aspects.The results showed that with the increase of continuous cropping years,soil total nitrogen continued to decrease,the content of available phosphorus and available potassium first increased and then decreased,the soil pH value increased year by year,the activity of SOD continued to increase,and the activity of POD and CAT first increased and then decreased.With the increase of continuous cropping years,the species and quantity of soil microbial community changed regularly,the abundance of some beneficial bacteria such as Actinobacteria and Gemmatimonadetes decreased year by year,and the abundance of pathogenic bacteria such as Ustilaginomycetes increased year by year.

In order to explore the genetic basis of drought resistance and guide drought resistance breeding, mapping of QTL associated with drought resistance at germination stage of foxtail millet was done. An F₂ segregating population was constructed using 100 individuals derived from a cross between Shanxi 2010 and K359×M4-1. A genetic linkage map was constructed based on 2b-RAD sequencing, which was then combined with the phenotypic trait of drought resistance for QTL mapping. The results showed that drought resistance at germination stage of foxtail millet was a complex quantitative trait and controlled by multiple genes. A genetic map containing 583 SNP makers was constructed by 2b-RAD of parents and F₂ population. The map covered 9 chromosomes of foxtail millet, with an average number of 64.8 and an average genetic distance of 0.97 cM between markers. A total of 3 QTLs were identified:qSIDR-5a, qSIDR-6a and qSIDR-6b, located in foxtail millet chromosome 5 and 6, respectively, which explained 12.4%-14.3% of phenotypic variation. Among them, phenotypic contribution rate of qSIDR-5a was the highest, which explained 14.3% of phenotypic variation. These QTLs were not included in the same chromosome interval as the identified drought resistance related QTLs of foxtail millet, and thus were described as new candidate gene loci associated with germination stage drought resistance.These QTLs can be used for fine mapping and gene cloning, as well as molecular regulation mechanism of drought resistance of foxtail millet.

To study the effects of salt stress on growth and physiological characteristics of sorghum at different growth stages(elongation, flowering, and maturity), two sorghum varieties with different salt tolerances, Gaoliangzhe(salt tolerance) and Henong No.16(salt sensitive), were planted at four salt treatment levels(CK:0 g/kg, S3:3 g/kg, S5:5 g/kg, S7:7 g/kg). Moreover, the two varieties were compared under different salt treatment levels, plant morphology, root morphology, leaf photosynthetic characteristics and antioxidant enzyme activities at different growth stages. The results showed that with increasing salt treatment concentration, the antioxidant enzyme activity and relative chlorophyll content(SPAD) of the two varieties increased first and then decreased. The antioxidant enzyme activity reached the maximum value under S3 or S5 treatment, and there were significant differences between the maximum and CK. With the increase of salt treatment concentration, the malondialdehyde(MDA) of the two sorghum varieties increased significantly, which S7 treatment was significantly higher than CK. Under the same treatment, the antioxidant enzyme activity of salt-tolerant varieties(Gaoliangzhe) was higher than that of salt-sensitive varieties(Henong No.16), but the content of MDA was lower than that of salt-sensitive varieties. The photosynthetic capacity of the two varieties was significantly affected by salt stress. In elengation, S7 treatment significantly reduced the Pn of Gaoliangzhe, and Ci of the two varieties under S7 treatment was higher than that of CK. Under salt stress, the growth of the sorghum aerial portion and underground portion of sorghum were affected. The basal stem diameter, total length of root, root surface area, number of root tips, and number of root branches for two varieties reached the maximum under S3 treatment. And basal internode length, plant height, total length of root and root volume reached the lowest value under S7 treatment. In addition, grain fat content and grain starch content in two sorghum varieties decreased under salt stress.The grain tannin content was significantly higher than CK in low-salt (S3, 3 g/kg). In general, low-salt can promote the growth of sorghum, while medium-salt (S5, 5 g/kg) and high-salt (S7, 7 g/kg) conditions have a significant inhibitory effect on sorghum growth. And Gaoliangzhe is more salt-tolerant than Henong No.16.

Intracellular acid phosphatase (ACP) is an enzyme which hydrolyzes phospholipids in vacuoles to inorganic phosphorus. The ACP enzyme is also ubiquitous in plant tissues and plays an important role in regulating plant phosphorus nutrition. It will be one of the main genetic and breeding approaches to solve the deficiency of available phosphorus in soil by developing new varieties assisted superior alleles and haplotypes in SiACP genes. First identified 13 ACP family genes form foxtail millet and other three gramineous crops by homologous alignment. After systematic bioinformatics analysis,it was found that the number and distribution of ACP family genes in gramineous crops had certain regularity,and they all had highly conserved phosphatase domains and motifs. In addition,through the analysis of family evolutionary tree,it was found that the ACP genes of monocotyledons and dicotyledons had obvious branches in the evolutionary process. Finally,expression pattern analysis of transcriptome data showed that SiACP1 genes in foxtail millet apparently exhibited a tissue specific expression,while the higher expression of SiACP2 and SiACP3 genes was found in different tissues through the growth and development stage. Meanwhile,through candidate gene association analysis and haplotype analysis,SNPs located in SiACP1 promoter was significantly associated with the traits with low phosphorus tolerance. Interestingly,a haplotype ACPHap2 which was favorable to low phosphorus tolerance of foxtail millet was preliminarily identified. Research results will provide some genetic information reference for the discovery of excellent germplasm with low phosphorus tolerance and molecular breeding of crops in further.

Foxtail mille is a C₄ gramineous crop with drought resistance, barren-tolerance, wild adaptability and high adverse resistance. To reveal the role of the genes expression characteristics under light and stress of foxtail millet, the genes related to abiotic stress were explored in this experiment. A PPDK gene, named as SiPPDK2, was identified in foxtail millet genome by bioinformatics method. SiPPDK2 was located on chromosome 3 in foxtail millet genome, which contained 18 introns. It contained 3 transcripts and primary alternative transcript encoding 945 amino acids residues. Subcellular localization predictions indicated that SiPPDK2 was mainly localized in chloroplasts. Functional domain and multiple sequence alignment analysis revealed that SiPPDK2 protein had a more closely relationship with PPDK proteins in maize, sorghum and rice. RT-PCR analysis showed that the expression of SiPPDK2 at its seedling stage was induced by PEG, ABA, salt and low temperature treatments. Further studies indicated that SiPPDK2 was involved in drought stress and different light intensity at the jointing, heading and filling stage, in which the expression was significantly increased under the drought condition at heading and filling stages and under the low light condition at jointing and filling stage. cis-elements analysis revealed that hormonal, stress, light, and other growth-related responses cis-elements were present in the promoter region of the SiPPDK2. The results speculated that SiPPDK2 is involved in the response to abiotic stress in foxtail millet.

For study the differences of structure and characters of protein and starch between wheat and foxtail millet, and find new ways to improve the quality of wheat, the total protein, glutenin and gliadin of wheat and foxtail millet were extracted by total protein extraction method, the extraction of high and low molecular weight glutenin method, and alcohol soluble protein extraction methodrespectively,and the protein bands were identified by SDS-PAGE(total protein and glutenin) and A-PAGE(glidain). The differences of structure of protein and starch between wheat and foxtail millet were observed and analyzed by scanning electron microscopy (SEM). The results showed that the grain of foxtail millet almost not contained glutenin, and contained some alcohol-soluble protein with polymorphisms.The grain of wheat contained A, B, C three kinds of starch, while the grain of foxtail millet was found two kinds of starch only.And the starch of foxtail millet is polygonal and smaller than that of wheat. Above all, the structure, shape and composition of starch and protein of foxtail millet and wheat were quite different.It may provide a new way to improve the quality of foxtail millet by modifying starch and protein synthesis genes like wheat.

To understand the regulation mechanism of exogenous 2,4-epibrassinolide (EBR) on photosynthesis of oats under NaCl stress, the effects of exogenous EBR on photosynthetic gas exchange parameters, fluorescence kinetic parameters, photosynthetic electron transfer rate and PSⅡ light energy distribution of oat seedlings were studied under 100 mmol/L NaCl stress with Avena sativa L. cv. Jiayan 2 and Qingyin 2 as experimental materials. The results showed that, NaCl stress significantly reduced the photosynthetic pigment content of oat seedlings, inhibited the activity of PSⅡ reaction center, and led to the decrease of PSⅡ photochemical efficiency and Net photosynthetic rate (Pn) of oat seedlings. Compared with NaCl stress, exogenous EBR treatments significantly increased the contents of chlorophyll a (Chla), chlorophyll b (Chlb) and carotenoids in the leaves of oat seedlings; significantly increased photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and water use efficiency (WUE),but decreased intercellular CO₂ concentration (Ci); exogenous EBR treatments also significantly increased maximum fluorescence (Fm), photochemical quenching (qP), photochemical quantum yield of photosystem II (ФPS Ⅱ), potential photochemical efficiency (Fv/Fo),maximal chemical efficiency (Fv/Fm), conversion efficiency of antenna pigment (Fv'/Fm'), photosynthetic electron transport rate (ETR), PSⅡ photochemical reaction energy (P), but reduced initial fluorescence (Fo) and non photochemical quenching coefficient (NPQ), antenna heat dissipation (D) and reaction center dissipation (E). In conclusion, exogenous EBR could significantly improve the actual photochemical efficiency of PSⅡ reaction center of oat seedlings under NaCl stress, effectively alleviate the photoinhibition and the degree of damage in the PSⅡ reaction center induced by NaCl stress, and improve the carbon assimilation efficiency and photosynthetic capacity of oat seedlings. These results indicated that exogenous BRs played a positive role in the regulation of the photosynthesis under salt stress, which could alleviate the damage caused by salt stress on oat seedlings.

Analysis of the expression pattern of florigen gene (Hd3a)under different photoperiod conditions,aims at revealing the role of florigen gene that played in photoperiod-regulated flowering process of foxtail millet. First,a SiHd3a gene sequence(Seita.4G067600,named SiHd3a)on Chr.4 of foxtail millet was obtained by bioinformatics method and according to the transcribed sequence of Seita.4G067600,a pair of specific primers were designed successfully. Then the total RNA of millet land race Huangmaogu was extracted and after reverse transcription the cDNA sequence of SiHd3a gene was obtained by RT-PCR technology. The cDNA sequence was 792 bp which included a 537 bp CDS region that coding 178 amino acids. The molecular weight,isoelectric point of SiHd3a protein were 19.74 ku and 6.82 respectively,which was preliminarily judged as a hydrophilic protein. The proportion of irregular curl was the highest in protein secondary structure(43.26%),following it were extended chain(β-sheet,29.21%),α-helix(16.29%)and β-turn(11.24%). Subcellular localization analysis showed that SiHd3a protein was located in the cytoplasm and intercellular substance. Phylogenetic analysis based on Hd3a protein sequences showed that there was a close relationship between foxtail millet and crown,maize,sorghum,but a distant relationship between foxtail millet and rice. Semi-quantitative PCR showed that under short-day condition, SiHd3a gene gave a circadian rhythm expression pattern,with two expression peaks at six am,and twelve am respectively. While under long-day condition, SiHd3a gene gave almost stable expression level in 24 hours. It could be speculated that the diurnal expression pattern difference of SiHd3a gene between long-day and short-day might be the cause leading to photoperiod sensitivity of foxtail millet.

Leaf color mutant is one of the ideal materials to explore the development mechanism of chloroplast and the utilization of C4 light energy in foxtail millet. To study the molecular mechanism of leaf color mutant in foxtail millet,we screened and identified a stripe leaf mutant wsl2 from the EMS mutagenesis library of the main variety Changnong 35. The mutant was studied through phenotype identification,genetic background detection and genetic analysis,location of the mutant gene rapidly and precisely with MutMap method and developing co-isolated molecular markers according to the mutation site. The results showed that wsl2 showed stripe leaf phenotype at seedling stage,but returned to normal leaf phenotype from jointing stage. wsl2 had the same genetic background as the wild type by detecting the genetic background. And wsl2 was controlled by a recessive nuclear gene with genetic analysis. The association interval contained 9 non-synonymous mutant genes by MutMap method. Seita.9G561800 encoded a PsbP-like protein associated with chloroplast,containing 6 exons and 5 introns. A G/T base mutation occured at 77 bp in the first exon,resulting in an arginine(R)becoming leucine(L). The mutation site of candidate gene in wsl2 mutant was further verified by the dCAPS marker MRI498-1(Cac8 Ⅰ)and the co-isolation marker MRI501-3. This study identified a new stripe leaf mutant wsl2, which laid a theoretical foundation for further study on the mechanism of photosynthesis reaction of PsbP gene,enriched the resources of leaf color mutant,and verified the effectiveness of MutMap method in cloning mutant gene in foxtail millet.

In order to explore the effects of silage sorghum on beef cattle growth performance, digestion and blood index, the nutritional combination of various silage sorghum was considered comprehensively to meet the nutritional needs of beef cattle, in order to promote the development of modern beef cattle economy in China. In this study, three simmental steers were used as experimental cattle, and BJ0603 silage was used as basic diet. Three cattle were selected from each diet treatment group for slaughtering and segmenting. Growth performance, digestion and blood indexes were measured. The results showed that silage sorghum had no significant effect on liver function, lipid metabolism and electrolyte level of fattening beef cattle. Mixed silage of 50% silage sorghum and 50% silage maize could significantly increase the content of urea nitrogen in blood. It could not only increase the energy utilization rate of beef cattle, but also had no adverse effect on the kidney function of beef cattle.

The WRKY transcription factor is involved in the developmental process and stress response of plant. To better understand the function of foxtail millet SiWRKY03 gene, its biological characteristics was analyzed by means of bioinformatics software. Real-time PCR was used to survey the expression profile in different tissues and the rust resistance response. The results showed that the open reading frame of SiWRKY03 gene contained 1 137 bp, encoding 378 amino acids with a WRKY conserved domain. The predicted protein molecular weight was 39.73 ku and the theoretical isoelectric point(pI) was 5.91. The largest secondary structure element of SiWRKY03 protein was random coil, and the smallest element was beta turn. Phylogenetic analysis showed that SiWRKY03 protein had 99% homology with those of Panicum miliaceum (RLM93064.1) and Panicum hallii (PAN29607.1). Expression patterns showed that SiWRKY03 gene of foxtail millet was expressed in roots, stems, leaves and panicles at booting stage, and the highest expression level was in roots and the lowest in panicles, which was consistent with the result of transcriptome data. During the responses to rust stress of foxtail millet, the expression of SiWRKY03 gene was up-regulated at 12,36 h in disease resistance response, but it had no significant change in the whole process of susceptible reaction, suggesting that SiWRKY03 played a positive regulatory role in the rust disease resistance of foxtail millet. The results provided a theoretical foundation for further study of the SiWRKY03 function and its resistance mechanism in foxtail millet.

The sugar transporter(STP)gene family plays critical roles in monosaccharide distribution and participates in diverse plant metabolic processes. To investigate the potential roles of STPs in sorghum growth and development, the genome-wide identification, classification and expression analyses of the STP gene family were performed in this study. A total of 19 SbSTP genes containing the Sugar_tr conserved motifs were identified from the sorghum genome, which distributed on 9 chromosomes unevenly, and 4 of them located in the genome segmental duplication region. According to their phylogenetic features, the 19 SbSTPs were further classified into 5 main groups, with high similar motif compositions within the same group, but they were different in exon-intron number. The synteny analysis and phylogenetic comparison of STP genes from sorghum, Arabidopsis and rice provided the valuable clues for revealing the evolutionary characteristics of SbSTP genes. RNA-Seq data analysis showed that 18 of the 19 SbSTP genes could expressed in various tissues with distinct expression patterns, among which SbSTP11 exhibited tissue-specific expression in flower, while SbSTP4 and SbSTP5 expressed in root or shoot by induction of ABA and PEG stress. The results provided a valuable resource for better understanding the biological roles and application potentiality of individual STP genes in sorghum.

In order to reveal the genetic mechanism controlling plant height, provide foundation for marker-assisted selection of ideal-plant type in foxtail millet, 98 foxtail millet materials were selected to investigate plant height in Hainan, Luoyang and Jilin, three different planting regions corresponding to three different photoperiod conditions, and further genome resequencing was performed for the 98 foxtail millet materials to carry out genome-wide association between SNPs and plant height. The results showed that the variation range of plant height was from 58.5 cm to 169.3 cm among different photoperiod conditions, the broad-sensed heritability was 0.501. With the prolonging of day length, plant height of foxtail millet gave an incremental trend. 4 482 208 high-quality SNP loci were obtained by resequencing, 98 foxtail millet materials were divided into three subgroups by principal component analysis. LD analysis showed that the genome LD decline distance of foxtail millet was 47.5 kb. Genome-wide association analysis obtained 10 703 SNPs associated with plant height(P<0.000 1), most of which were detected in Hainan planting region(short-daylength condition)and centralized on Chr.1. Only three associated SNPs(SNP_13861443, SNP_14872616, SNP_18601830)on Chr.1 could be stably detected in two planting regions(Luoyang and Hainan, which represented two different photoperiod environments), indicating that Chr.1 harbored QTLs controlling plant height of foxtail millet in Hainan(short-day)and Luoyang(moderate-day)planting regions. Three candidate genes were found in regions around associated SNPs, only the putative Formin protein gene(LOC_101783280) gave a mutation site in exon region(SNP_14876527), which indicated that the Formin protein gene might be the main candidate gene controlling plant height.

This study aims to investigate the response of foxtail millet phosphoenolpyruvate carboxylase gene under abiotic stress. The SiPEPC(Seita.1G020700)gene was identified from the foxtail millet genome, and the amino acid sequence, protein characteristics, function, signal pathway, homeopathic response components and other parameters of SiPEPC were analyzed and predicted using corresponding software. Subsequently, the dynamic expression pattern of the gene at seedling stage under the stress and its expression at jointing, heading and filling stages under different light treatments and drought stress were analyzed. The results indicated that SiPEPC was located on chromosome 1 of foxtail millet. The sequence analysis showed that SiPEPC had a length of 6 652 bp, encoding 965 amino acid residues. SiPEPC had no alternative splicing and intron. Functional domain analysis showed that SiPEPC contained the characteristic domains of PEPC gene. Multiple sequence alignment revealed that the SiPEPC protein had a very conserved sequence, which was very similar to PEPC proteins in other plants. qRT-PCR analysis showed that the expression of SiPEPC (Seita.1G020700)was up-regulated under ABA, low temperature, PEG and high salt stress treatments. Under ABA treatment, the expression level fluctuated and reached to peak at 12 h. Under low temperature treatment, the expression level continued to rise and reach to the highest at 24 h. The overall trend of expression increased when treated with PEG and NaCl, and peaked at 12 h, but decreased sharply at 24 h. Further studies showed that SiPEPC gene participated in the response to drought stress under normal light intensity at jointing and heading stages. These results suggested that SiPEPC (Seita.1G020700)gene participated in the response to abiotic stress and might play a key role in signaling pathway of drought or other stresses.

In order to quickly detect the conditions of Aphelenchoides besseyi contamination in millet seeds and understand the population variations of Aphelenchoides besseyi from different regions, a total of 99 millet seed samples collected from different millet production regions of China were detected by PCR technology, and the population variation of Aphelenchoides besseyi was analyzed. The results showed that the specific primers designed according to the 28S rRNA-D2/D3 fragment of Aphelenchoides besseyi had a high specificity and sensitivity to millet nematodes, and could amplify a fragment of 245 bp with the lowest test concentration of 0.125 ng/μL Aphelenchoides besseyi. Among the 99 millet seed samples, 33 samples were detected to be contaminated, in which the contamination rates ranged from 33.3% to 100%, and they mainly distributed in spring millet areas. The sequence analysis of 28S rRNA fragments from 33 positive samples revealed that there were 29 variable sites and 22 haplotypes, of which the haplotype AB1 was the dominant haplotype. The haplotype genetic diversity of Aphelenchoides besseyi was the most abundant in Zhangjiakou, Hebei Province and Songshan District, Inner Mongolia. In this study, a PCR-based detection method was established to detect Aphelenchoides besseyi in millet seeds with a good specificity and high sensitivity, which could be used to detect the millet seeds carrying Aphelenchoides besseyi. The millet nematode is a major disease in summer millet areas, but with the millet exchange between spring and summer millet areas, it has become a disease in spring millet area. The seed carrier may be the main primary infection source. The 28S rRNA sequences of Aphelenchoides besseyi from different geographic origins were diverse, and AB1 was the dominant haplotype.

Sensitivity to photoperiod is the main reason for narrow ecological adaptability and lacking cross-regional cultivars of foxtail millet. Identification of QTLs associated with millet photoperiod sensitivity is the foundation for further exploring genetic mechanisms of photoperiod sensitivity. 45 millet cultivars were surveyed for heading date in long-day region (Luoyang City, Henan Province) and short-day region (Ledong County, Hainan Province). The photoperiod sensitivity values of 45 millet cultivars were calculated according to the difference between the heading date in the two regions. Then, 40 pairs of SSR markers were used to determine the genotypes of these millet cultivars. Finally association analysis between SSR markers and photoperiod sensitivity was performed. The results showed that a total of 150 alleles were detected in 45 millet cultivars, giving an average allele number of 3.75 per locus. Of the 40 SSR markers, b200 and b124 amplified the most number of alleles (6 alleles per locus). Based on the SSR markers amplification data, the population genetic structure of 45 millet cultivars was analyzed, and the optimal K value was 3, so the 45 millet cultivars were divided into three subgroups. The first subgroup included 5 cultivars, the second subgroup included 16 cultivars and the third subgroup included 21 cultivars. The remaining three cultivars could not be grouped into any of the three subgroups, consisted of a mixed group. The linkage disequilibrium analysis showed that no significant linkage disequilibrium structures were found among 40 SSR markers. Finally association analysis between SSR markers and photoperiod sensitivity were performed, two loci, b200 (SSR8) and b127 (SSR35) were detected to associate with photoperiod sensitivity(P<0.05).

To accelerate marker assisted selection molecular breeding of oat, we had performed genotyping-by-sequencing (GBS) analysis in a group of oat verities with multiple years of drought tolerance characteristics, including 18 low drought tolerance, 13 moderate drought tolerance, 11 high drought tolerance and 12 uncharacterized oat varieties, respectively. GBS libraries were constructed by PstⅠ/MspⅠ double restriction enzymes digestions and subsequently sequenced based on next generation sequencing technology. Using Stacks pipelines, the reduced oats reference genome were annotated and populations SNPs of each sample was identified through Stacks pipeline. The significance was analyzed using PCA, Fisher Test (Hommel package, R script) and Blast. Sequencing results showed that the number of high quality reads in oat individuals ranged from 4 111 218 to 19 019 296. In total, 753 325 references sequences were annotated. By refer to the reference sequences, the populations SNPs were determined for each sample and in total 74 657 SNPs were identified. Based on the populations SNPs, PCA analysis showed that two clusters were formed, one cluster primarily consisted of 14 low drought tolerance germplasm, whereas another one harbors all 11 high drought-tolerance germplasm. Furthermore, comparison between low and high drought tolerance oats showed that in total 2 937 SNPs were significantly and differentially expressed (FDR<0.05). Blasting of 55 SNPs with the most significant difference (FDR<0.001) hosting sequences indicates 14 SNPs might be involved in variant biological pathways including plant hormone signal transduction. This annotated genomic sequences by this study greatly enriched the present available oat genome database. By alignment with the wheat genomic database, the identified 14 SNPs might play an important role of advancing oats molecular breeding. Moreover, it provides a solid technical basis for further large scale screening of oats germplasm.

The quantitative genetic analysis of the agronomic traits of the sorghum F₂ population was carried out to determine the optimal genetic model of each trait and to master its genetic laws, which provided a reference for the agronomic traits in the field breeding genetic stability. F₂ populations derived from grain sorghum variety Xinliang 52 and Meiyin-20 were used as material, of which 6 agronomic traits were analyzed through major gene plus polygene mixed genetic model for quantitative traits. The results showed that among the six agronomic traits, the plant height, the length of the stalk, the number of main stems, and the average stem length were in accordance with the quantitative genetic model, which were controlled by major genes, while the spike length and flag sheath length were not controlled by major genes but inherited by micro genes. The plant height was well fit into Model B_1, i.e. The mixed genetic model of additivity-dominance-epistasis, which was controlled by two major genes, and the heritability of major genes was 88.65%; the ear handle length and main stem numbers was coincidence with the Model A_1, i.e. The additive-dominant hybrid genetic model for master-gene control, and the heritability rates were 61.58% and 68.94%, respectively; the average internode length was fit with Model A_4, i.e. The negative fully dominant genetic model, and the heritability rate was 49.24%. The genetic rate of the main gene of plant height, ear handle length and main stem numbers were higher than the other indices, indicating that the three traits were less affected by the environment in the inheritance of the offspring, the inheritance was relatively stable and could be directly selected in the early generation of breeding, while the heritability of the average internode length was lower, indicating that this trait was genetically unstable in the offspring, and was affected by the environment, which need to be selected in the high generation of breeding.

To explore the effect of nitrogen on senescence characteristics of fodder oat leaves,in Horqin sandy land, using oat as material,pure nitrogen of 0 (CK), 70, 140, 210, 280 kg/ha was applied to oats at seedling stage, tillering stage, jointing stage and heading stage in proportion of 15%, 40%, 25% and 20%.Leaf area, chlorophyll content, soluble protein content, antioxidant enzyme activity and membrane peroxidation degree were measured. The results showed that the application of nitrogen fertilizer had an obvious effect on delaying leaf senescence and improving functional leaf time and efficiency.In a certain range with the increased of nitrogen, chlorophyll content, leaf area of oat were significantly improved, the soluble protein content increased, while MDA content decreased, SOD activity decreased significantly, POD activity and CAT activity were significantly enhanced, delaying leaf senescence.When the nitrogen was more than 210 kg/ha, continuing to increase nitrogen application, flag leaf area and chlorophyll content and soluble protein content decreased significantly, and could not improve leaf POD and CAT activity after flowering, but the activity of SOD was significantly increased;MDA content increased significantly.This experiment also indicated that scavenging oxygen free radicals in plants was not a single enzyme action. It depended on the synergistic action of SOD, POD and CAT protective enzymes. The application of 210 kg/ha nitrogen fertilizer in the Horqin sandy land had the strongest anti-aging ability.

Tillering is an important trait related to yield in many crops,and is the same for yield improvement of foxtail millet. However, the genetic mechanism of tillering in foxtail millet (Setaria italica) remains largely unknown. To accelerate mapping of relevant QTLs or genes, a restriction site-associated DNA sequencing (RAD-seq) approach, MSTmap and WinQTLCart 2.5 were employed to identify QTLs responsible for tillering in two F₂ populations called Cross AJ (543 F₂ individuals) and Cross HC (131 F₂ individuals). A total of six QTLs including qAJTN1, qAJTN5, qAJTN7-1,qAJTN7-2, qAJTN7-3 and qAJTN9, were identified in Cross AJ, explaining 0.7%-9.8% of the phenotypic variance, and two QTLs including qHCTN5 and qHCTN7 were identified in Cross HC, explaining 1.4%-8.3% of the phenotypic variance. Of which qAJTN1, qAJTN5, qAJTN7-2, qAJTN9 and qHCTN5 were newly identified QTLs, and qAJTN7-1, qAJTN7-3 and qHCTN7 were consistent with previous reports. Meanwhile, we screened the insertions and deletions in the QTL regions compared with the reference genome, insertion-deletion (InDel) markers linked with tillering were developed. These results of this study will facilitate the revelation of the genetic mechanism of tillering and molecular marker-assisted breeding of foxtail millet.

Exogenous selenium was sprayed at different growth stages of the foxtail millet to study the change rule of quality and grain selenium content, to determine the optimum spraying selenium period for foxtail millet, so as to provide a theoretical basis for production of selenium-rich foxtail. The varieties Changnong 35, Jigu 20 and Jingu 50 were used as test materials. The field experiment was designed by random block group, setting spray water for control (CK), foliar spraying Na₂SeO₃ 67.84 g/ha at seedling stage, heading stage and filling stage to study on influence of quality, grain selenium content, accumulation and translocation of selenium in foxtail millet. The result showed that different growth period of spraying selenium treatment all could improve quality of foxtail millet, foxtail millet in filling stage spraying selenium on millet quality traits to improve was the best. The lysine content of Jingu 50, Jigu 20 and Changnong 35 increased by 0.03,0.05,0.02 percentage points respectively, folic acid content was 2.4%, 7.5%, 5.5% higher than that of control, respectively.The content of crude protein and crude fat in selenium spraying treatment reached extremely significant level with the control during grain filling stage(P<0.01).Spraying time impact on grain selenium content in filling stage > heading stage > seedling stage, foxtail millet grain selenium content was increased by average of 8.0-9.9 times compared to the CK within the scope of the safety of the intake of selenium. Filling stage was to improve the millet organic selenium conversion rate and the utilization ratio of the grain selenium crucial period.The organic selenium conversion rates of Jingu 50, Jigu 20 and Changnong 35 treated by spraying selenium at grain filling stage were 13, 13 and 10 percentage points higher than those of the control, respectively, and there was a significant difference between them (P<0.05), compared with the control, the selenium harvest index increased by 5.32, 5.82 and 2.70 percentage points after selenium treatment in the filling stage. The application of selenium in filling period could improve the quality of grain, increase the grain selenium content, the conversion of organic selenium and the utilization of selenium. Filling stage was an optimal period of foxtail millet foliar spraying exogenous selenium.

Rhizosphere soil microorganisms play an important role in the regulation of soil rhizosphere environment and nutrient transformation. Sorghum has been widely used as forage and strong barren tolerance.Study of rhizosphere microorganisms on the ecological response of different nutrients,which can provide the theoretical basis for nutrient management of different soil nutrients under conditions of sorghum. This paper was based on the long-term field test of sorghum/corn rotation,combined with the pot experiment of artificial greenhouse. BIOLOG micro plate was applied to test the effect of NPK,PK,NK,NP fertilizers and CK (without fertilization) on sorghum rhizosphere soil microbial functional diversity. The results showed that the field test was in agreement with the pot experiment. PK treatment increased the metabolic activity of rhizosphere microorganisms,and improved the utilization of amino acids,carboxylic acids,amines,sugars and polymers,and reduced the utilization of amphiphilic compounds. The Shannon-Wiener index(H),Richness index(S) and Simpson index(Ds) were higher than other treatments. The effects of NK and NP on the functional diversity of rhizosphere microorganisms were not significant,but NK treatment reduced the microbial metabolic activity in the rhizosphere of the late culture. CK treatment significantly decreased the rhizosphere microbial utilization of carbon sources,the Shannon-Wiener index(H),Richness index(S) and Simpson index(Ds) were lower than other treatments,Substrate evenness(E) higher than other treatments. Principal component analysis showed that there was no significant difference in rhizosphere soil microbial carbon source utilization capacity and type between NPK and NP treatments,and the rest treatments showed significant difference in the field test. In pot experiment,the difference of carbon source ability and type of NPK,NK and NP treatment was not significant,and the difference between the other treatments was significant. In summary,fertilization was conducive to improving soil microbial characteristics. The responses of sorghum rhizosphere microorganisms to nitrogen,phosphorus and potassium stress were different. When nitrogen stress was applied,the increase of soil microbial activities in sorghum rhizosphere was probably the cause of nitrogen tolerance in sorghum.

Salt tolerance is an important agronomic trait of sorghum. Salt tolerance genetic analysis is important for sorghum breeding. In order to select new varieties of salt-tolerant sorghum and study the genetic rules of salt tolerance, 482 F₅ recombinant inbred lines were obtained from the salt-tolerant cultivar Sanchisan and salt-sensitive cultivars Tx622B, and the germination rate, seedling height, fresh weight and dry weight were used to identify salt tolerance at seedling stage. Genetic analysis was carried out by single-generation combined quantitative trait analysis. The results showed that the sal-tolerance traits of the Sanchisan and salt-sensitive cultivars Tx622B were significantly different. The relative mean values of germination rate, seedling height, fresh weight and dry weight of the F₅ generation group were all different among parents, and the tolerance to salt tolerance was different in different degree. The germination rate, seedling height, fresh weight and dry weight were analyzed. There were significant positive correlations between the two traits. The relative germination rate, relative seedling height, relative fresh weight and relative (B-5)genetic model of two pairs of major genes were found by genetic model analysis. Through genetic model analysis, it was found that salt tolerance of F₅ population of recombinant inbred lines of sorghum was dominant to salt, and inheritance of salt-tolerance trait of sorghum was in line with complete dominant (B-5)genetic model of two major genes. The heritability of the major gene of germination rate was 40.94%. The heritability of major gene of seedling height was 31.22%. The heritability of major gene of fresh weight was 39.19%. The heritability of main gene of dry weight was 63.98%.The germination rate, seedling height, fresh weight and dry weight have high heritability as the main characters of salt tolerance evaluation, and have far-reaching significance for the selection and cultivation of sorghum salt-tolerant varieties.

Sorghum is a global crop for food security,human health and bio-energy development. It is considered one of the model crops for diploid cereal species and a reference crop for polyploid species like sugarcane and Miscanthum. It is important to develop molecular markers for genetics research and marker assisted selection in sorghum breeding. The parental lines,a sweet sorghum variety and a grain sorghum variety,and their F₂ progenies were employed to develop Specific-Locus Amplified Fragment Sequencing(SLAF) markers,from which a large amount of SNP markers were obtained by using a high-throughput sequencing technology. A total of 43 528 021 SLAF-seq reads were generated,including 2 598 472 reads from the maternal variety,and 3 134 524 reads from the paternal variety,and 205 083 to 454 258 reads with an average of 290 732.5 from each F₂ individual. High quality SLAF tags generated form the maternal and the paternal varieties were 44 895 and 42 100,with sequencing depth of 19.78 and 16.22-fold,respectively. High quality SLAF tags from the F₂ progenies ranged from 26 737 to 39 291(average 33 445.06) with a sequencing depth of 2.24 to 3.72-fold(average 2.79). A total of 6 353 polymorphic SNP markers were obtained,in which 5 829(91.75%) were successfully genotyped and 2 246 high quality markers have been obtained with 100% efficient and an average of 94.99% integrity. Results showed that it was a useful way to obtain SNP markers covering whole genome through high-throughput sequencing technology. This study has laid a foundation for linkage map construction,QTL identification and marker assisted breeding in sorghum.

Cloning a male sterility gene from foxtail millet male sterility material 1066A, analyzing the mutation sites between sterility gene and fertile gene, which could provide foundation for exploring molecular mechanism of male sterility, breeding multi-purpose male sterility materials by marker assisted selection method. A putative male sterility gene was cloned from 1066A based on the complete foxtail millet genome sequence data and location results of predecessors to explore mutation sites leading to sterility,which could provide foundation for uncovering male sterility mechanism at molecular level and breeding multi-purpose male sterility materials by marker assisted selection method.Firstly,a male sterility gene with total length of 5 027 bp (coded 479 aa,Si015780m.g) was found on chromosome 6 of foxtail millet cultivar Yugu 1 by bioinformatics method,and the gene was in the same genome region as that located by molecular markers. Two pairs of specific primers were designed according to male sterility gene sequence of Yugu 1 to amplify corresponding male sterility gene of 1066A (a male sterility material).Totally 2 561 bp gene sequence was obtained after assembling of two amplification fragments,which contained part code region downstream of the gene.After sequence alignment of part coding regions and putative protein sequences of male sterility gene from Yugu 1,Zhanggu and 1066A,three mutation sites including two single base substitutions and one base insertion were found in coding region of male sterility gene from 1066A.Two base substitutions led to Ile (402) and Leu (403) from protein of Yugu 1 and Zhanggu were replaced by Val and Ile from protein of 1066A,and one base insertion led to premature translation termination of protein from 1066A when reached the 466th aa.Of the three mutation sites, two aa substitutions had limited effect on function of coding protein,so we suggested that premature translation termination of protein from 1066A male sterility gene would be the reason for its sterility phenotype.This study provided foundation for uncovering molecular mechanism of male sterility in foxtail millet.