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.

Plant growth and production are faced with various biological and abiotic stresses,among which salt stress seriously affects the normal growth and development,quality and yield formation of plants.Plants have evolved morphological structure,physiological and biochemical reactions and genetic basis to adapt to salt stress during the long process of evolution.In terms of morphological structure,the leaves of salt-tolerant plants have waxy layer and lower stomatal density than those of salt-sensitive plants,and salt glands,microhairs,salt vesicles,and casparian strip have salt secretion or blocking functions.In terms of physiological activity regulation,on the one hand,salt-tolerant plants have high enzymatic and non-enzymatic antioxidant substances,such as SOD,CAT,phenolic substances,on the other hand,salt-tolerant plants have a high content of osmoregulatory substances,or can synthesize osmoregulatory substances under salt stress,including soluble proteins and sugars of organic substances and inorganic ions.In terms of molecular mechanism,SOS pathway is the most clearly studied ion regulation pathway,which maintains intracellular Na⁺/K⁺ balance through the synergistic action of SOS1,SOS2 and SOS3.In addition,plant hormones and carbon metabolism pathways also play an important role in the process of plant salt tolerance.This paper summarizes the research progress of salt-tolerant plants,and discusses the potential research focus and direction of salt-tolerant plants in terms of morphological structure,physiological basis,genetic molecular basis and transgenic methods in response to salt stress,which will help researchers quickly find the breakthrough point,gradually improve the mechanism system of salt-tolerant plants,and accelerate the efficient utilization of salt-tolerant plants.

The transcription factor BnHY5-2 is associated with plant stress resistance.In order to reveal the response of Brassica napus L.transcription factor BnHY5-2 to salt alkali stress in B.napus,the response of BnHY5-2 to light and salt and alkali was analyzed by transient overexpression,qRT-PCR analysis and subcellular localization.The results revealed that under light conditions,the expression level of the BnHY5-2 gene in B.napus leaves and stems was 29.22 and 3.15 fold higher,respectively,compared to dark conditions.The higher sensitivity to light in leaves suggested that they were the primary site for light signal response.Under light conditions,the expression of BnHY5-2 in leaves and stems was significantly downregulated by 53.1% and 31.0%,respectively,when B.napus was planted in Dalian coastal saline-alkali soil;after applying saline-alkali treatment under dark conditions,the expression of BnHY5-2 was downregulated by 48.2% in the stem,while the difference in expression in the leaves was not significant,indicating organ differences,indicating that the leaves had stricter requirements for light conditions.In B.napus leaves with transient overexpression of BnHY5-2,two out of six genes related to saline-alkali stress(BnNAC32 and BnGS)showed upregulation by 1.25,3.28 fold,respectively,while the other four genes(Bnamy,BnAsp,BnNHX7,BnTPS)were downregulated by 24.8%,25.4%,71.0%,and 82.0%,respectively.Meanwhile,the content of the resistance substance betaine in B.napus increased from 0.256 to 0.573 mg/g,indicating an enhancement by 1.24 fold,suggesting that the overexpression of BnHY5-2 gene could improve the saline-alkali tolerance of B.napus.Subcellular localization results showed that the transcription factor BnHY5-2 was localized in the nucleus and regulates the expression of functional genes.Therefore,BnHY5-2 is not only related to light signaling but also participates in the saline-alkali resistance of Brassica napus L.

To provide a solid foundation for studying the biological function of WRKY family members in kenaf in response to salt stress,all members of WRKY family were identified and their expression patterns were analyzed.Physical and chemical properties,phylogeny and conserved functional domains of WRKY gene family members were analyzed by bioinformatics method.The expression characteristics of WRKY gene family members under salt stress were analyzed by RT-PCR.The results showed that a total of 33 WRKY family members were identified,which were unevenly distributed on 12 chromosomes.There were certain differences in the physical and chemical properties of each member,such as amino acid number,molecular weight and theoretical isoelectric point.The conserved sequence WRKYGQK of each member did not change.Phylogenetic tree analysis showed that 33 WRKY family members were divided into 3 groups,GroupⅠ,GroupⅡ,Group Ⅲ,of which Group Ⅲ contained 5 subgroups.The real-time fluorescence quantitative RT-PCR results showed that there were 26 WRKY family members induced by salt stress,of which 23 had positive regulation and 3 had negative regulation.A total of 33 WRKY family members of kenaf were identified,of which 26 WRKY family members were involved in the salt stress response of kenaf.

In order to explore the effects of saline-alkali stress on the physiological and molecular mechanism of Brassica napus L.,using Huayouza 62 as experimental material.The seedlings of Brassica napus L.were treated with different concentrations of compound salt,compound alkali and compound saline-alkali solution.Physiological indexes such as seed germination rate,chlorophyll content,proline content,soluble sugar content and antioxidant enzyme activity in Brassica napus L.leaves were determined.The accumulation of betaine in rape leaves was determined by high performance liquid chromatography(HPLC).The key enzyme gene choline monooxygenase gene(CMO)in betaine synthesis pathway was analyzed by qRT-PCR technique.The results showed that the degree of damage to seed germination in artificially simulated saline-alkali solution of different concentrations was compound saline-alkali>alkali>salt.Low concentration saline-alkali solution promoted chlorophyll formation in rape leaves,while high concentration saline-alkali solution inhibited chlorophyll formation,saline-alkali stress significantly increased the contents of proline and soluble sugar,and the contents of proline and soluble sugar in high saline-alkali solution(YJ75,saline-alkali 75 mmol/L)for 21 d were 65.99 and 5.21 times higher than those in the control group,respectively,and the content of malondialdehyde was increased by saline-alkali stress.Saline-alkali stress significantly increased the activity of peroxidase(POD).Compared with the control group,the content of POD in high saline-alkali solution(YJ75)increased by 2.26 times after 21 d,and the content of POD reached the highest value on the 14th day after treatment with compound salt and compound alkali,however, the activity changes of superoxide dismutase (SOD) and catalase (CAT) were not obvious, and the role of species in the process of saline-alkali stress was low.Saline-alkali stress significantly increased the expression of key enzyme gene CMO,thus regulating the accumulation of betaine.In summary,the damage degree of saline-alkali stress to Brassica napus L. was compound saline-alkali > alkali > salt.Under high saline-alkali stress,Brassica napus would accumulate a large amount of betaine to reduce the damage.

In order to explore the effects of growth and aging characteristics of peanut under drought and salt stress,using Huayu 25 as material,potted experiment was carried out to study the change of peanut growth and aging characteristics due to the stress of drought and salt at flowering stage.The results showed that drought treatment (D),salt stress treatment (S),drought and salt stress (DS) increased the content of soluble protein,soluble sugar,free amino acid,proline,O₂^· and MDA. S treatment and DS treatment reduced the activity of SOD,POD and CAT in the leaves,which continued to decrease as time prolonged. But D treatment enhanced SOD and CAT activity in the leaves. After 10 days of rehydration,the content of soluble sugar,soluble protein,free amino acid,proline,O₂^· and MDA of D treatment reduced compared with the numerical values which detected before rehydration.D treatment had no significant difference with CK,including activity of SOD and POD and content of O₂^·,MDA,soluble sugar,free amino acid,proline. However,the difference of the activity of SOD,POD,CAT of DS treatment was significant compared with S treatment,so did the content of O₂^· and MDA.In the harvest time,single plant yield and the kernel rate of D treatment had no significant difference with CK,but DS treatment had significant difference with S treatment. Data from DAT9 showed that drought and salt stress had no significant interaction with soluble sugar,soluble protein,free amino acid and proline content in leaves. However,there was significant interaction of SOD,POD,CAT activity and O₂^·,MDA content between drought stress and salt stress. The interaction between drought stress and salt stress inhibited the activity of SOD,POD and CAT and exacerbated the peroxidation of plant cell membranes. Eventually it decreased the single plant yield and the kernel rate. Therefore,peanuts planting under salt stress should avoid the drought at flowering stage to reduce the harm of salt stress,drought stress and the interaction between salt stress and drought stress.

The effect of different concentrations salt stress on seedling growth and expression of related genes were explored in this study. Firstly, salt tolerant variety Yura Hama Daikon and susceptible variety Wujinhong were selected according to germination under salt stress conditions among 11 cultivars.And then the seedling height(SH) and the leaf scorch index(LSI) of Yura Hama Daikon and Wujinhong were investigated under salt stress treatment.The results showed that SH decreased and LSI increased under salt stress in both varieties.Compared with the salt-sensitive variety Wujinhong,the salt-tolerant variety Yura Hama Daikon had a smaller decrease in SH and lower LSI.Under 200 mmol/L salt stress,SH and LSI of salt-tolerant Yura Hama Daikon were 46.18% and 20.56,respectively,while those of salt-sensitive Wujinhong were 75.25% and 56.11.The transcription of RsCAT and RsSOD genes was studied in salt-tolerant and susceptible varieties under different salt concentrations by qPCR.The expression of RsCAT gene was first increased and then decreased under low salt concentration treatment,and reached the maximum at 7 day.When treated with high salt concentration,the transcription of RsCAT in Wujinhong was the highest at 48 h,while the expression level in salt-tolerant varieties increased gradually and maintained for a longer time,reaching the highest at 7 day.After high salt concentration treatment,the transcription of RsSOD gene reached the highest expression level at 24 hours,and then maintained a higher level in salt-tolerant variety.In salt-sensitive varieties,the maximum expression level of RsSOD appeared at 14 day.The above results will lay foundation for revealing the mechanism of salt stress in radish and provide technical support for radish salt-tolerant breeding.

Application of some hormonal signaling compounds,as brassinolides and their derivatives,could significantly improve the salt stress resistance in plants.The purpose of present work was to test whether the over-expressing of Methylsterol monooxygenase gene(SMO),a key gene coding a bio-synthesizing enzyme of sterol in plants,could promote the salt-stress tolerance of target plants.PnSMO1.1,gene encoding of methylsterol monooxygenase in the plant species of Pharbitis nil was firstly cloned and then used as target gene for following genetic transformation process,while wild-type Pharbitis nil seedlings were used as the receptor plants for constructing of the transgenic lines which over-expressed PnSMO1.1 genes.In this work,the PnSMO1.1 gene transformed Pharbitis nil lines were constructed via an ovary injection transformation method.Plantlets from individual PCR identified transgenic plant lines were used as materials to detect vegetative growth figures and some pivotal physiological indicators,for instance,contents of malondialdehyde (MDA),relative conductivity,as well as castasterone and 6-deoxo-castasterone contents in cells under stresses with gradient NaCl conditions varied from 0—200 mmol/L.The results showed that the over-expression PnSMO1.1 significantly improved the relative growth of roots and hypocotyls in transformants than in wild-type (WT) or vacant plasmid transformed control (BL) plants under 100—250 mmol/L NaCl stresses.Compared to WT and BL seedlings,significantly higher accumulation of 6-deoxo-castasterone,but lower relative conductivity (rEC) values,castasterone accumulation or MDA contents were found in transgenic lines under various NaCl stresses.Stresses such as salinity,drought and freezing temperatures,had severely suppressed the vegetative growth of plants,as well as their yields.These results highlighted that over-expression of the PnSMO1.1 gene could significantly improve the salinity-stress resistance of transgenic plants by delicately adjusting the dynamic homeostasis of brassinolides in cells,and protecting the structural integrity of plasma membrane.

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.

To investigate the function of soybean GmPP2C89 gene in plant abiotic stress response and adaptation. The expression patterns of GmPP2C89 under NaCl,PEG and mannitol treatments were detected by transcriptome data and Real-time quantitative PCR. Then,the cis-acting elements on the promoter of GmPP2C89 in response to abiotic stress were analyzed,and promoters of different lengths were cloned according to the distribution of cis-elements to construct fusion GUS vectors to obtain the corresponding transgenic Arabidopsis. The response of the promoters to NaCl,PEG and mannitol was analyzed by GUS staining. Transgenic Arabidopsis overexpressing the GmPP2C89 was constructed,and the root length,leaf MDA content and electrolytic leakage,and the expression of salt stress-related genes(SOD,POD,CAT,RD26,RD29A,and RD29B)were measured under normal and NaCl treatment conditions. The results showed that NaCl,PEG and mannitol treatments all led to a significant increase in the expression level of soybean GmPP2C89;the promoter region contained many cis-acting elements such as ABRE,DRE,G-box,MBS,MYB,MYC and TC-rich repeats which were involved in abiotic stress response,and this promoter was more responsive to NaCl treatment. In addition,under the salt treatment,the root length of transgenic Arabidopsis GmPP2C89-OX was significantly greater than that of WT,while the MDA content and electrolytic leakage were significantly lower than those of WT,and the salt tolerance was significantly enhanced;the expression of antioxidant enzyme genes(SOD and POD)and ABA pathway key gene RD29B in GmPP2C89-OX was significantly higher than that in WT. These results indicated that soybean GmPP2C89 was induced by NaCl,PEG and mannitol,and GmPP2C89 overexpression could enhance the salt tolerance of transgenic Arabidopsis by activating antioxidant and ABA pathways.

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 explore the effects of cattle manure on soil salinity and sodicity on the sodic soil in long-term experiments,the experiments were performed in a randomized complete block design with four treatments;soils that received manure applications for 8,12,18 years were used as the experimental treatments,and soil that did not receive cattle manure application was used as the control treatment(CK).The results showed that the application of cattle manure to saline-sodic soil resulted in a reduction in the bicarbonate ion(HCO₃^-)contents,the elimination of carbonate ions(CO₃^2-),the decrease in soil bulk density(ρ_b),the increases in soil porosity(f_t)and soil organic matter(SOM),the decreases in the exchangeable and soluble sodium ion (Na⁺)contents associated with increases in the exchangeable calcium ion(Ca²⁺),soluble potassium ion(K⁺),and magnesium ion(Mg²⁺)contents compared to those in untreated soil.The soil exchangeable sodium percentage(ESP)and pH were both significantly and positively correlated with the exchangeable Na⁺ and HCO₃^-,and CO₃^2- contents,and soil pH was significantly and negatively correlated with SOM.Regression analysis showed that the dominant factors affecting the sodium absorption ratio(SAR)were the soluble Mg²⁺ and Na⁺ contents in the soil.Pearson correlation analysis showed that there were significantly negative correlation between the accumulated amount of cattle manure among the indicators of soil salinization degree,such as pH,EC,ESP and SAR.It was concluded that long-term manure application significantly decreased the soil pH,ESP,electrical conductivity(EC)and SAR due to the replacement of soil colloidal Na⁺ with Ca²⁺,the leaching of soil soluble salts from the topsoil and changes in the soil soluble salt ion composition.These outcomes were likely due to the decrease of ρ_b associated with increase of f_t and Ca²⁺ and Mg²⁺ contents caused by annual manure application.

NRL(NPH3/RPT2-Like)is a type of light-responsive protein unique to plants and plays a vital role in the phototropic signal pathway. To reveal the NRL gene maize genome's characteristics and expression,we analyzed them using bioinformatics methods combined with qRT-PCR technology. The property,structure,evolution of their encoded proteins,and growth period tissue expression and stress expression were analyzed. 31 ZmNRL genes identified were located in nine maize chromosomes,encoding protein amino acids 464-749 aa,which predicted to have chloroplast,nuclear and cytoplasmic locations. According to protein conservation,ZmNRL family was divided into four categories. Their gene structure also presented certain conservation,the most contained four exons. Analysis of the cis-elements of gene promoters revealed a large number of abscisic acids,jasmonic acid,light response,and anti-oxidation elements,among which G-box and Sp1 were two types of light-related elements. The expression of ZmNRL family genes in tissues during the growth period showed a temporal and spatial specificity,and the majority expression level was not high. Only ZmNRL2,ZmNRL4,ZmNRL24,and ZmNRL29 highly expressed. Furthermore,the characteristic modules were produced based on the data of the tissue co-expression genes. And the GO enrichment analysis of a particular leaf growth module containing six ZmNRL genes,mainly associated with the plastid organization biological processes and rRNA binding molecular functions. The expression of ZmNRL5,ZmNRL7,ZmNRL12,and ZmNRL19 genes were analyzed by qRT-PCR under salt,drought,high temperature,and Rhizoctonia solani inoculation treatments. The results showed that ZmNRL12 was significantly up-regulated in maize seedlings treated with high temperature,while ZmNRL5,ZmNRL7 and ZmNRL19 genes were down-regulated in drought,salt and pathogen treatments. In summary,31 ZmNRL genes were identified in the maize genome. They not only had apparent specific tissue expression but also participated in biotic and abiotic stress responses.

To identify the miRNAs and their response regular patterns to salt stress and drought stress,rice seedlings at three leaves stage were used to quantify the expression of miRNAs and their targets when treated with salt and drought stresses at 0,3,6,12,24,48 h by qRT-PCR. The results demonstrated that expression patterns of miRNAs were affected by space-time and tissues under salt and drought treatments. Further analysis indicated that the expressions of miR156,miR164,miR167,miR169, and miR171 upregulated in roots with time and expressions of miR159,miR160,miR319,miR398, and miR1848 downregulated at 3 h and then upregulated when treated with salt(NaCl). And the 10 miRNAs were performed their lowest expressions in shoots at 3 or 6 h under NaCl treatment. On the other hand,the expressions of the most of the 10 miRNAs downregulated in roots generally and expressions of miR156,miR159 and miR160 downregulated in shoots and the expression patterns of miR167,miR169,miR319,miR398, and miR1848 down regulated first and then upregulated when treated with drought(PEG). Furthermore,expression patterns of targets were also affected by space-time and tissues. And only few expression patterns of the 10 miRNAs negatively correlated with its target,which implied the complexity of the regulation network of miRNA and its target in response to stresses.

The number and the length of roots as well as its QTL would provide theoretical basis for genetic mechanisms and molecular marker assisted breeding of salt and alkaline tolerance. Recombinant inbred lines(RIL)of sensitive varieties Dongnong 425 tolerant varieties Changbai 10 cross were treated with 140 mmol/L NaCl and 0.15% Na₂CO₃ as salt and alkali stress,and normal condition as control. The number and the length of roots during seedling stage were measured,and using complete interval mapping(ICIM)of QTL IciMapping v3.3 software to analysis the QTL under salt,alkali and normal conditions. We detected eighteen additive QTL located on 1,2,3,4,5,7,8,9 and 10 chromosomes with LOD 2.01-3.35,and the contribution rate to phenotypic variation was 6.02%-20.06%.Under natural conditions,four QTL related to the root number were detected,among which,12.46% was the largest contribution rate of qNRN7-2,while no QTL were detected related to the root length. Under salt stress,five QTL were detected related to the number and length of roots,among which,20.06% was the largest contribution rate of qSRN3. Under alkali stress,three QTL related to the root number and root length were detected. The contribution rate of qARN2 was 12.99%,and the contributions of qARL3 and qARL5 were 7.04% and 8.88% respectively. We found four different number and length related QTL between normal and salt condition. Among them,the contribution rates of qN-SRN8-2 and qN-SRL1 were relatively large,14.01% and 14.12%,respectively.In normal and alkali conditions,two number and length related QTL were detected on 3 and 10 chromosomes. One QTL associated with root number, qN-ARN3,located on chromosome 3,with contribution rate 6.02%.One QTL were detected related to the number and length of roots,among which,7.45% was the largest contribution rate of qN-ARL10 on chromosome 10. Under alkali and salt stress conditions,the number and length of rice seedling roots were significantly affected,and compared with salt stress,rice was more sensitive to alkali stress.

In order to investigate the effect of salt stress on starch synthesis and accumulation of Japonica rice in cold-region and enrich the physiological basis of salt tolerance research.The paper used pot experiment to study the influence of different concentrations of salt stress on the key enzymes activities related to starch of Japonica rice in cold-region and the relationships between the changes rule in key enzymes activities and starch content, revealed the response mechanism of Japonica rice in cold-region kernel starch anabolism under salt stress,studied the effect of yield and yield components of Japonica rice in cold-region under salt stress, as well as the effect of yield formation mechanism of Japonica rice in cold-region under salt stress. The results showed that compared with the control, the activities of soluble starch synthase (SSS),ADPG pyrophosphorylase and starch branching enzyme(Q enzyme) in grain of Japonica rice in cold-region decreased under salt stress, and the contents of total starch and amylopectin in grain decreased, while the amylose content in grain increased. Meanwhile,with the increased of salt concentration, the indicators of yield components gradually declined, salt stress mainly affected the grain number per panicle and seed setting rate of MDJ30 and thus affected the yield, while LD5 was the effective panicle number and seed setting rate. When soil salt content was more than 0.075%, the theoretical yield was greatly affected. In terms of variety, compared with MDJ30, the salt-tolerance variety LD5 had relatively high starch synthase activity, which results in a higher content of starch and its components.This was beneficial to grain dry matter accumulation and ensure that its yield could still be maintained at relatively high levels under salt stress. Thus, the key enzyme activite of starch synthesis in kernel is different product of different salt-tolerant varieties responding to salt stress, the change rule and the level of its activity can be used as an indicator for salt tolerance identification.

In order to clarify whether existed autophagy phenomenon in sugar beet under salt stress and its relationship with plant salt-resistant physiological characteristics, the self-phage occurrence, reactive oxygen species content, osmosis regulating substance content and their relationship under different salt gradients were studied with salt-resistant sugar beet variety LS2004 and salt-sensitive sugar beet variety KWS7125 as experimental materials. The results showed that salt stress could induce autophagy in sugar beet seedlings. Autophagy was involved in the defense process of sugar beet seedlings against salt stress. The specific manifestation was that autophagy increased with the increase of salt concentration. Under the salt stress condition of 300 mmol/L, LS2004 had the strongest autophagy and the largest number of autophagosomes, which was 1.22 times that of KWS7125. The hydrogen peroxide content of KWS7125 and LS2004 reached the peak under the treatment of 200 mmol/L, which were increased by 40.06% and 41.54% respectively compared with that of the control. Under each treatment, the superoxide anion content and relative electrical conductivity of KWS7125 were higher than those of LS2004. The soluble protein content, proline content and total soluble sugar content of LS2004 firstly increased and then decreased with the increase of salt concentration, but there were differences in change rules with KWS7125. In summary, autophagy existed in sugar beet seedlings under salt stress, and the comprehensive effect of autophagy, alleviating oxidative damage, and osmotic adjustment substance content could be used by sugar beet seedlings to improve the salt tolerance of sugar beet.

In order to study the influence of silicon on the expression of pepper CaMADS-box gene under abiotic stress,such as the high temperature and salt stress,we used pepper 101 as experimental materials,the physical and chemical properties of encoding protein was analyzed,phylogenetic tree was constructed,subcellular localization was predicted through bioinformatics software on the base of the cloning of pepper CaMADS-box gene.The results showed that the cloned gene encoding protein CaMADS-box was hydrophilic protein,containing MADS domain structure,belonged to MADS gene families.And its subcellular localization was in the nucleus,the molecular evolutionary tree showed that close to Nicotiana,the similarity was 67%.Fluorescence quantitative analysis showed that CaMADS-box gene expression after high temperature stress and salt stress were presented first rise after the fall of the model, the difference was to peak at 48 h, under high temperature stress, salt stress peak at 24 h, silicon handle could induce gene expression CaMADS-box, under high temperature stress and salt stress were expressed at 12 h to reach peak, which suggested that CaMADS-box was a silicon quick response genes, speculated that the silicon handle in alleviating pepper abiotic stress such as high temperature and salt stress plays an important role.

In order to study the effects of NaCl stress with different concentrations on physiological characteristics and gene expression of TaNHX1,two new wheat varieties (Luyuan 502 and Qingmai No.6)were used as the experimental materials.Physiological indexes of seeds germination rate,seedlings fresh weight,roots vigor,plasmalemma permeability,MDA content and Na⁺ content of the two wheat varieties were determined under above 100 mmol/L NaCl stress of 50,100,150 and 200 mmol/L,and compared the relative expression of tolerant gene TaNHX1 in roots and stem base of wheat through RT-qPCR method.The results showed that the seeds germination rate of Qingmai No.6 was more than that of Luyuan 502 under above 100 mmol/L NaCl stress.Low concentration NaCl stress had significant promoting effect on seedlings growth of Qingmai No.6,and the seedlings fresh weight of Qingmai No.6 significantly decreased under NaCl stress of 150 mmol/L,while that of Luyuan 502 began to decreased significantly under NaCl stress of 100 mmol/L.The roots vigor of Luyuan 502 decreased significantly more than that of Qingmai No.6 under high concentration NaCl stress.Under the same concentration NaCl stress,the leaf plasmalemma permeability and MDA content of Luyuan 502 were significantly more than that of Qingmai No.6,it indicated that NaCl stress had less damage on leaf cell membrane of Qingmai No.6.Na⁺ content of roots and stem base of Qingmai No.6 were all significantly more than that of Luyuan 502 under high concentration NaCl stress,it indicated that Na⁺ exclusion capability of roots and stem base of Qingmai No.6 was significantly more than that of Luyuan 502,which could effectively restrict Na⁺ transporting to shoot.The TaNHX1 gene of Luyuan 502 and Qingmai No.6 respectively reached the highest expression level under NaCl stress of 100,150 mmol/L.It indicated that Qingmai No.6 is more salt tolerant than Luyuan 502,and the maximum concentration of salt tolerance of Luyuan 502 is 100 mmol/L,while that of Qingmai No.6 is 150 mmol/L.

To study the function of lipid transfer proteins(LTP)in abiotic stress,the ZmLTP3 gene was transferred into maize Jing 2416 inbred lines by pollen tube pathway method. Positive transgenic lines were obtained by continuous selfing based on the screening of PCR and EPSPS. Three transgenic lines OE6,OE10 and OE18 were selected as the experimental group,and Jing 2416 inbred lines(WT)were used as CK. Both of them were subjected to salt stress. Morphological and physiological indexes were compared between OE and WT lines. The results showed that OE and WT plants showed no significant differences in both morphological and physiological indexes under normal condition. Under the salt stress condition,compared with WT plants,the OE plants had significantly higher height,stem diameter,root length,fresh weight,dry weight and chlorophyll content,significantly higher activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT),significantly lower malondialdehyde(MDA)content and relative conductivity ratio level,showing their better growth status,higher active oxygen radicals scavenging capacity and less cell injury. These results indicated that overexpression of ZmLTP3 gene could improve the salt tolerance in transgenic maize.

To assess the peanut rhizosphere bacteria community structure in response to salt stress at different development stages, the peanut variety Huayu 25 was used as experimental material, and a pot experiment was set with three salt concentrations to study the effect of salt stress on peanut yield and analyze the changes of microbial community structure of peanut rhizosphere at flowering and harvest stage under salt stress by high-throughput sequencing technology. The results showed that the rhizosphere microbial composition of peanut were basically similar under different salt stress treatments, but the diversity and richness significantly varied between flowering and harvest stage. Under higher salt stress, the diversity and richness of rhizosphere bacterial community were increased at the flowering and needling stage but decreased at the harvest stage. The dominant bacteria phyla of all soil groups were Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria, Verrucomicrobia, Bacteroidetes, and Patescibacteria. The relative abundance of Cyanobacteria, Gammaproteobacteria, Verrucomicrobiae and Bacteroides significantly increased under salt stress, especially at the flowering and needling stage. Hierarchical clustering revealed that the microbial community diversity was markedly altered by the salt concentrations and growth stages, samples of the same growth period were clustered into one group under salt stress. KEGG functional prediction analysis indicated that sequences related to carbohydrate metabolism, amino acid metabolism, energy metabolism, and metabolism of cofactors and vitamins were enriched, whereas that of signal transduction mechanisms, lipid metabolism, replication and repair, xenobiotics biodegradation and metabolism, metabolism of other amino acids, and folding, sorting and degradation were decreased. Among them, salt stress increased the abundance of functional groups involved in substance and energy metabolism, membrane transport, translation, replication and repair, and signal transduction, but decreased the 100 fruit weight and 100 kernel weight of peanut resulted in the decrease of peanut yield. Therefore, salt stress had a great impact on the peanut rhizosphere bacterial community structure and peanut yield. The salt tolerance of peanut could be enhanced by improving soil microbial environment. The results provided a theoretical basis for the development of peanut production in saline-alkali areas.

Based on randomized block experimental design,a field experiments was conducted to investigate the effects of different nitrogen fertilizer,high efficiency organic fertilizer and amendments on wheat yield,maize yield and soil fertility in the rotation system of wheat and maize on coastal saline areas.The aim of these experiments was to providing a certain theoretical guidance about soil fertility and crop yield in coastal saline soil.The results showed that the application of nitrogen fertilizer,high efficiency organic fertilizer and amendments could increase grain yield of wheat.And the yield increased 9.52%-29.52%,2.30%-17.82%,2.19%-11.48% respectively.The application of nitrogen fertilizer,high efficiency organic fertilizer could increase grain yield of maize,and the yield increased 29.37%-45.74%,1.69%-11.15% respectively.There was obvious yield increasing effect on corn yield after wheat amendments,and the yield increased 3.50%-8.33%.Application of nitrogen fertilizer,high efficiency organic fertilizer and amendments had a significant effect on improving soil fertility in coastal saline soil.O3(N₂O₃A₂) had the highest available nitrogen,available phosphor,available potassium content in all treatments;Application of amendments increased soil organic matter content and decreased the soluble salt contents in soil.Under the conditions of this experiment,the highest wheat and maize annual production reached 16 770.46 kg/ha,which obtained by mathematic simulation,and the optimum economic amounts of nitrogen fertilizer,organic fertilizer and amendment were 763,2 250,3 167 kg/ha,respectively.Therefore,in order to obtain high yield and get higher economic efficiency,we should pay attention to combine application among nitrogen fertilizer,high efficiency organic fertilizer and amendments in the rotation system of wheat and maize on coastal saline areas.

In this experiment, the nutrient release characteristics of sulfur coated urea in mild saline-alkali soil were studied by water extraction and mild saline-alkali soil incubation method, and compared with humic acid coated urea and common urea.At the same time, the trials were conducted to investigate its effects on the absorption of nitrogen and yields of spring maize.The results indicated that in the water, sulfur coated urea had a large initial release rate of nutrient, and "locked-in effect" and "tailing effect" in its later period, and the nutrients could be only released the 60%.It had the same trend in the mild saline-alkali soil with in the water, but the nutrients released rate was 87.9% when the maize was harvest, during the whole growth period of maize, the accumulated release showed a gradual increasing trend, that fitted to the curve of the captured by nitrogen in maize.And compared with the release of humic acid urea and common urea, the difference of the nitrogen absorption curve of the corn was in the degree of the difference.In different fertilization treatments, the treatments of sulfur coated urea was better than the treatment of humic acid urea and common urea, the increment rate of maize nitrogen absorption amount was 26.97% and 44.32%, respectively, the yield of corn increased by 8.73% and 22.43%, respectively;the seedling soil pH value decreased 0.66 and 0.51 units respectively.The spike length and 100 grain weight per treatment in the treatment of sulfur coated urea were significantly higher than those of the humic acid coated urea treatment and common urea treatment, the increment rate was 1.33%, 4.65% and 2.69%, 8.41%, respectively.The treatment of sulfur coated urea had significant difference with the common urea treatment in bald and per spike grain.It can be seen that the application of sulfur coated urea in mild saline alkali soil has lower pH, increasing the nitrogen absorption and utilization of maize plant, and the release characteristics of the absorption law of nitrogen in maize.

In order to excavate the role of exogenous silicon(Si) in salt stress response and explore the regulation mechanism of salt stress response, the cotton variety Xinluzao 45 was used as test material, and was treated with 3 levels of salt(NaCl:0, 100, 200 mmol/L) and 2 levels of silicon(K₂SiO₃:0, 262.3 mg/L). The changes of seedling growth, osmotic regulation, reactive oxygen, malondialdehyde(MDA) content and electrolyte leakage rate were measured after the treatment of exogenous Si, and the effect of silicon in relieving the inhibitory effect of NaCl on cotton seedlings were studied. The results showed that, compared to CK, the fresh leaf weight, dry leaf weight, stem fresh weight, stem dry weight, root dry weight, root cap ratio, root activity, malic acid and citric acid of cotton seedlings all showed a downward trend along with the increase of NaCl levels, while the contents of free proline(Pro), hydrogen peroxide(H₂O₂) and malondialdehyde, the rate of electrolyte leakage and the oxygen free radical(O₂^·) production presented a upward trend, and SS and free amino acid contents increased first and then decreased. The biomass and osmotic regulator of cotton seedlings increased obviously in the same salt treatment after application of exogenous silicon, while the rate of O₂^· production, electrolyte leakage rate, the contents of hydrogen peroxide and malondialdehyde in cotton seedlings decreased obviously. Comprehensive analysis showed that the salt stress could inhibit the growth of cotton seedlings, and with the increase of salt concentration, the inhibition effect and osmotic stress degree aggravated. The exogenous silicon increased the accumulation of osmotic regulation substances and reduced the accumulation of active oxygen in cotton seedlings, so it could alleviate the inhibiting effect of salt stress on cotton seedling growth and improve the salt resistance of cotton seedlings.