Chalcone synthase(CHS)is an important structural gene that regulates the early biosynthesis of flavonoid pathways in plants,and plays a role in plant growth and development and stress response.Previously,the key genes StCHS4 and StCHS5 for anthocyanin biosynthesis were identified in the potato CHS family by expression analysis.To further explore the function of potato StCHS4 and StCHS5 in the biosynthesis of flavonoids and anthocyanins,the characterization of StCHS4 and StCHS5 proteins was analyzed by online website.The 35S∷StCHS4-GFP and 35S∷StCHS5-GFP recombinant vectors were constructed by homologous recombination method based on the pRI101 binary vector,and then were transformed into Agrobacterium GV3101 strain.The subcellular localization of StCHS4 and StCHS5 proteins was determined by transient transformation of Nicotiana benthamiana.N.tabacum was used as the experimental material for transient overexpression and stable genetic transformation to analyze the content of total flavonoids and anthocyanins after overexpression of StCHS4 and StCHS5 genes.The results showed that the secondary structures of StCHS4 and StCHS5 proteins were mainly α-helix and random coil.StCHS4 was an unstable hydrophilic protein,and StCHS5 was a stable hydrophilic protein.The sequence alignment revealed that StCHS4 and StCHS5 had a close relationship with the CHSs of Capsicum annuum and Solanum lycopersicum,respectively.The results of subcellular localization revealed that StCHS4 and StCHS5 proteins were localized in the cytoplasm and cell membrane.In transient overexpression of tobacco,StCHS4 and StCHS5 genes significantly enhanced anthocyanin accumulation at 3—5 days after injection.Three transgenic N.tabacum lines of StCHS4 and StCHS5 gene were obtained,respectively.Compared with the wild type,the expression of StCHS4 and StCHS5 in transgenic plants was significantly higher,and the contents of total flavonoids and total anthocyanins were higher than those in the wild type.The total flavonoid content in StCHS4-OE3 and StCHS5-OE1 transgenic plants was significantly increased.The anthocyanin content in StCHS5-OE1 and StCHS5-OE2 plants increased by 89%,131%,respectively.The above results demonstrated that StCHS4 and StCHS5 were the key CHS genes in the flavonoid pathway of Solanum tuberosum,and the overexpression of StCHS4 and StCHS5 contributed to the biosynthesis of anthocyanins and flavonoids.

In order to investigate the effects of reactive oxygen species(ROS)on the growth and antioxidant system of sweetpotato under potassium deficiency stress,and further reveal the defense mechanism of ROS regulation in sweetpotato under potassium deficiency stress.This study selected two sweetpotato varieties,Xushu32(low potassium tolerant)and Ningzi 1(low potassium sensitive),as experimental materials.The experiment was conducted in an artificial climate chamber using hydroponic cultivation to ensure consistent environmental conditions.After pretreatment with exogenous H₂O₂ and diphenyl chloroiodate(DPI),ROS inhibitor,the sweetpotato seedlings were subjected to potassium deficiency treatment.The changes in relative H₂O₂ content,antioxidant gene expression levels,and enzyme activity indicators in sweetpotato roots at different time points after potassium deficiency treatment were measured.The morphological characteristics of sweetpotato were recorded to explore the effects of ROS signaling on the growth of sweetpotato seedlings under potassium deficiency stress.The results showed that under potassium deficiency treatment,the biomass of sweetpotato decreased and leaf color lightened.The relative concentration of ROS in sweetpotato seedling roots showed the highest fluorescence intensity on the 14th day.The expression levels of antioxidant-related genes in sweetpotato roots generally increased,with a more significant increase in expression levels after H₂O₂ pretreatment.Compared with-K treatment,both H₂O₂ and DPI pretreatment could enhance the activity of antioxidant enzymes in sweetpotato leaves,and different enzyme activities showed different trends within 21 days of potassium deficiency treatment.There were varietal differences in the effects of different treatments.The experimental results showed that H₂O₂ could act as a stress signaling molecule to increase the expression level of antioxidant genes and the enzymatic activities of APX,SOD and POD in sweetpotato seedlings,thus scavenging excess ROS and effectively alleviating the inhibition of growth of sweetpotato seedlings by potassium deficiency stress.And DPI could inhibit the production of endogenous H₂O₂,maintain the antioxidant enzyme activity,protect the ROS enzymatic scavenging system of sweetpotato seedlings and avoid oxidative damage to tissues.

In order to study the role of phototrapping pigment binding protein gene in potato photosynthesis,the phototrapping pigment binding protein gene StCP24 (LOC102586836)was bioinformatics analyzed and cloned into potato variety Dongnong 310 to obtain transgenic potato.The morphological indexes,leaf physiological indexes,fluorescence parameters,and gene relative expression of transgenic and control lines were measured under different light intensities after clonal propagation.The function of StCP24 gene was analyzed.The effect of this gene on chloroplasts was determined by ultrastructural observation.The results of bioinformatics analysis showed that StCP24 protein was a hydrophilic protein,and the promoter of StCP24 gene contained elements such as photoresponse,defense and stress response.Phylogenetic analysis showed that the amino acids encoded by StCP24 gene in potato were closely related to those encoded by StCP24 gene in cultivated tomato.Under different light intensity treatments,StCP24 gene overexpressed potato significantly increased stem diameter,leaf area,leaf weight,root length,chlorophyll a,b content,Fv/Fm,ETR,ETRmax and qP compared with wild-type potato.The overexpression of StCP24 gene can make the lamellar stacking of thylakoid granules more tightly and to a higher degree.In conclusion,the overexpression of StCP24 gene can increase the content of chlorophyll a and b in leaves,improve the electron transfer rate in photo cooperative photoreaction,and promote the growth of transgenic potato plants.

To explore the expression patterns of potato genes and provide theoretical basis for the subsequent study of gene resistance to potato diseases.Three endogenous small G protein genes StRac5,StRac7 and StRac13 were cloned from potato,and their bioinformatics and expression patterns were analyzed.The results showed that StRac5,StRac7 and StRac13 contained similar conserved sequences to the small G proteins in Arabidopsis and rice,all belonging to ROP proteins.The protein domains of StRac5 and StRac13 were identical with AtRop1,AtRop3,AtRop5,AtRop6 of Arabidopsis and rice OsRac5,OsRac6,OsRac7,and StRac7 was identical with AtRop9.Phylogenetic tree analysis showed that StRac7 belonged to class Ⅱ and was closest to Arabidopsis AtRop9.StRac13 belonged to class Ⅲ and was the closest genetic relative to Arabidopsis AtRop7.StRac5 belonged to class IV and was the closest genetic relative to rice OsRac5 and OsRac6.The relative expression levels of StRac5,StRac7 and StRac13 genes in different tissues of potato were leaf>root>stem.Compared with the expression in stems,the expression of StRac5,StRac7 and StRac13 in leaves were increased by 1 222.4%,2 531.3% and 468.2%,respectively.After inoculation,the relative expression of StRac5,StRac7 and StRac13 genes increased first and then decreased,and the relative expression of StRac5 and StRac13 genes increased by 62.2%,40.4%,respectively,compared with 0 h after inoculation 24 h.The relative expression of StRac7 gene was increased by 827.8% at 72 h after inoculation compared with 0 h.After ABA,SA,GA and 6-BA treatment,the relative expression of StRac5,StRac7 and StRac13 genes showed a downward trend.After JA and IAA treatment,the relative expression of StRac5,StRac7 and StRac13 genes showed an up-regulated trend.Therefore,StRac5,StRac7 and StRac13 genes can respond to potato late blight infection,and their expression patterns are different in different tissues and under different hormone treatments.

In order to investigate how to alleviate the effects of insufficient light in potato production,the potato variety Dongnong 310 was used as the test material,and three shading treatments were set up:normal light(Z₀,blackout rate is 0),single-layer blackout screen covering treatment(Z₁),double-layer blackout screen covering treatment(Z₂).Different concentrations of epbrassinolide(0 mg/L,denoted as CK)were sprayed in the potato tuber formation stage(0.02 mg/L,denoted as E₁;0.10 mg/L,labeled E₂).Three measuring periods were set,the plant height,chlorophyll a,b content,photosynthetic parameters,fluorescence kinetic parameters,and yield per plant were measured and analyzed.The relative expression levels of LHcb genes in 12 leaves were measured.The results showed that Z₁ conditions were more suitable for the growth of Dongnong 310,while Z₀ conditions produced photoinhibition,and the indexes were lower than Z₁.Under the condition of Z₂,the illumination was insufficient,and the indexes were lower than that of Z₁.EBR spray could effectively increase the yield per plant,and E₂ treatment under Z₀ condition significantly increased by 32.62% compared with CK,E₁ and E₂ treatment under Z₁ condition significantly increased by 48.38% and 24.24% compared with CK,respectively,E₂ treatment under Z₂ condition significantly increased by 18.45% compared with CK.In terms of weight of dry matter per tuber,E₂ treatment under Z₀ condition increased by 27.24% compared with CK,and E₁ and E₂ treatment under Z₁ condition increased by 40.09% and 26.56% compared with CK,and the above differences were significant.The relative expression of 12 LHcb genes could be increased by increasing the shading degree and spraying EBR,which was conducive to improving the light energy capture and utilization in leaves.

To clarify the effect of callus treatment on the quality of sweet potato,provide a theoretical basis for high quality storage of sweet potato.Two edible varieties of sweet potato were stored and taken at different storage periods(0,7,15,30,60 and 90 d).Different degree of injury were carried out on them.The experiment was divided into four treatments: CK, high temperature callus,callus after shallow injury,and callus after deep injury.Then put materials in an incubator with relative humidity of 85% at 35 ℃ for 48 h to healing the wound.The diameter of soft rot spots,the activity of epidermal defense enzymes(PPO,POD,PAL)and the content of nutrients in potato pieces were measured.The results showed that the spot diameter of sweet potato root increased with the extension of storage period after inoculation of Rhizopus stolonifera. Sweet potato treated with callus was more resistant to soft rot than sweet potato stored in ordinary environment.After storage for 90 days,the diffusion diameter of soft rot spots of the two varieties after callus treatment with shallow injury was only 74.6% and 71.1% of that of the control treatment.At the early stage of storage, the activity of defense enzymes in each treatment remained at a high level from 0 to 30 d. After 90 d of storage, the activity of defense enzymes after callus injury treatment was significantly higher than that of control treatment. At 60 d of storage, the sucrose content of root tuber of two varieties with treatments of callus after shallow and deep injury was significantly higher than that of CK. Callus treatment of sweet potato after different degrees of injury during storage period can significantly increase the activity of defense enzymes in sweet potato epidermis,reduce the spread speed of soft rot infection,and improve the resistance of sweet potato to soft rot.The degree of injury had influence on the callus effect of sweet potato.The callus after shallow injury was better than that of deep injury in terms of defense enzyme activity and storage quality.

To express the protein StSPS1 encoding potato sucrose phosphate synthase(SPS)in E.coli and prepare polyclonal antibodies.The StSPS1 gene was cloned from the tubers of tetraploid potato variety Chuanyu 10,with a total coding region of 3 165 bp and a protein length of 1 055 aa.Subsequently,based on the constructed His tag fusion expression vector PET30a-StSPS1,the protein induction,denaturation,purification,renaturation,and rabbit immune tests of StSPS1 protein were carried out.The results showed that the molecular weight of StSPS1 protein was approximately 119.62 ku,and its expression was minimal in soluble supernatant,mainly in insoluble precipitates.The optimal induction conditions were induced with 0.5 or 1.0 mmol/L IPTG at 37 ℃ for 4 h.Due to StSPS1 being an inclusion body protein,it was subjected to inclusion body denaturation and purified using His tags to match the size of the target band.At the same time,a protein immunoblotting(WB)test was performed using His antibodies,and the target band was detected at 119.62 ku,indicating the successful purification of StSPS1 inclusion body protein.Finally,by injecting the dialyzed and refolded StSPS1 protein into the subcutaneous tissue of rabbits,two antibodies against StSPS1 were successfully immunized.After WB identification,it was found that both antibodies could hybridize target bands in the antigen and the total protein of leaves in Chuanyu 10.In summary,potato StSPS1 protein was induced and purified,and rabbit polyclonal antibodies against StSPS1 protein were successfully prepared.

Anthocyanins are a kind of important flavonoids produced during the secondary metabolism of plants.Anthocyanidin synthase(ANS)catalyzes the conversion of leucoanthocyanidins to anthocyanidins in the anthocyanin synthesis pathway.Previous studies have shown that the anthocyanidin synthase gene plays an important role during the coloring process of plant organs.To investigate whether the gene can promote anthocyanin synthesis in potato tubers,using the red-skinned and red-fleshed colored potato variety Hongmei as the material,anthocyanidin synthasegene was isolated from tubers of color potato by RT-PCR, the characterization analyzed by bioinformatics and function validated by overexpression into Arabidopsis thaliana.The results showed that sequence 1 406 bp cDNA of the gene was amplified from the potato,including 1 368 bp open reading frame(ORF).The ORF encoded a deduced protein of 455 amino acids.The gene was named as StANS1a by bioinformatics analysis.GenBank accession number is ON512347.The amino acid sequence analysis revealed that the deduced protein contained a DIOX_N'domain located at 52—166 resides and a 2OG_FeⅡ_Oxy domain located at 215—312 resides.Arabidopsis thaliana plants was transformed with constructs overexpression vector StANS1a.The transcriptional expression of StANS1a in transgenic lines were tested by RT-PCR.The results showed that in the same population,the transcriptional expression of StANS1a showed an increase in different transgenic lines compared with the wild-type(Wt).The anthocyanin content was further analyzed in transgenic lines.Compared to the Wt,the anthocyanin contents of the seven lines(T₁—T₇)were increased from 2.17% to 54.61%. These results strongly demonstrated that overexpression of the StANS1a gene could promote anthocyanin synthesis in transgenic plants.The colored potato StANS1a gene plays an important role in the anthocyanin metabolic pathway.

In order to study the effect of different irrigation methods and ridge planting experiments on water use efficiency and yield of potato in dryland,and to identify an optimal ridge planting and irrigation combination mode of potato with high yield and water use efficiency simultaneously,and further provide a theoretical basis for the production efficiency of dryland potato.The two-factor experiment was persistently performed in Lanxian County Shanxi Province during two potato growing seasons(2019—2020).The three ridge planting,including conventional ridge cultivation(M₁),concave ridge cultivation technique(M₂)and outdoor planting(M₃);the two irrigating including hydraulic driving zonal sprinkler(G₁)and drip irrigation(G₂),deeply exploring the effects of ridge planting and irrigation and their interaction effects on water use efficiency and yield of dry potato.The results showed that irrigation and ridge planting had obvious regulation effects on water use efficiency and yield of dry potato.Compared with M₁ and M₃,M₂ could significantly increase soil use efficiency water storage consumption.Under G₁ treatment,the water use efficiency and yield of M₁ and M₂ treatments increased by 14.08%,13.58%,and 23.28%,21.92%,respectively,compared to M₃;under G₂ treatment,the water use efficiency and yield of M₁ and M₂ treatments increased by 11.88%,11.50%,and 22.05%,20.45%,respectively,compared to M₃,and the combination of concave ridge cropping + hydraulic driving zonal sprinkler irrigation treatment combination G₁M₂ had the highest yield.Under the same ridge planting,the water use efficiency and yield of hydraulically driven zonal sprinkler irrigation(G₁)were the highest.Based on the regulating effects of ridge planting and irrigation on water use efficiency and grain yield,the G₁M₂ treatment could help synchronously to improve the grain yield and water use efficiency.This can be an optimal model of ridge planting and irrigation combination treatment of dry potato area of Shanxi Province.

The study aims to understand the biological process and metabolic pathway of konjac under different root separation modes from black locust,in order to provide molecular basis for the expression regulation and response mechanism of related genes in intercropping konjac roots.Illumina NovaSeq 6000 sequencing technology was used for transcriptome analysis of konjac roots separated by plastic membrane(FS),nylon mesh(MS),and non-separation(NS).A total of 59.82 Gb data were obtained,and 92 358 transcript sequences corresponding to 40 122 Unigenes were generated after de novo assembly and quantitative assessment.The most annotated Unigene in the NCBI-Nr database was 23 960,accounting for 59.72% of the total Unigenes.The transcriptome data were pair-wise compared,and the total quantities of differential expression genes of FS_vs_MS,FS_vs_NS and MS_vs_NS were 1 776,733 and 896,respectively.Of which,their corresponding up-regulated genes accounted for 33.1%,22.8% and 50.8%.GO enrichment analysis indicated that significantly differential expressed genes were mainly involved in plasma membrane,cell membrane,cell periphery,cell wall,encapsulating structure,intrinsic components of membrane,and intrinsic components of plasma membrane.KEGG enrichment analysis showed that the ribosome,oxidative phosphorylation and plant hormone signal transduction were the most significant metabolic pathways in the roots of konjac separated by nylon mesh and non-separation compared with plastic membrane.Transcriptome analysis of konjac roots provided the basic data for studying response mechanism of intercropping konjac.

RPP13 is a typical R gene that can induce plant immune response by recognizing of the effectors.The transcriptome sequencing analysis of five potato cultivars infected with Potato spindle tuber viroid (PSTVd)showed that RPP13 genes were up-regulated in the five potato cultivars infected with PSTVd.In order to study whether this gene was related to PSTVd resistance in potato,DNAMAN 8.0 software was used to perform sequence alignment analysis on RPP13 upregulated gene sequences obtained by transcriptome sequencing.The common conserved region was selected as the silencing object,and a stem-loop structure inverted repeat with the conserved region as the arm and the intron from somatic embryogenesis receptor-like kinase 1 (SERK1)(Accession number EF175216)as the loop was inserted in plant expression vector pROKⅡ to construct RNAi vector named pROKⅡ-RPP13.The pROKⅡ-RPP13 vector was transferred into Agrobacterium tumefaciens LBA4404 by freeze-thaw method,and the potato cultivar Minfenghong was transformed by Agrobacterium tumefaciens mediated genetic transformation method. Healthy potato leaves of 28 days of seedling age were used as materials. After 2 days of pre-culture, 10 minutes of infection, 2 days of co-culture under dark conditions, roots and buds were induced by the resistance screening medium. The regenerated plants were screened by PCR, and three positive transgenic plants were obtained.Using efla gene of potato as the reference gene,Real-time RT-PCR was used to detect the expression of RPP13 gene in potato transformed plants.The results showed that the expression level of RPP13 gene in the three transgenic plants obtained was significantly different from that in the control without transgenic.In the obtained RNAi transgenic potato plants,the expression level of RPP13 gene was decreased by 35%—60%.

In order to explore the molecular mechanism of diploid potato material response to drought stress under different drought stress time treatment,and explore drought resistance related genes.The high drought-resistant diploid resource A90 was used as experimental material,and transcriptome sequencing technology was used to analyze the differentially expressed genes under PEG-6000 stress at different times.Differentially expressed genes involved in drought stress response of potato were predicted by GO enrichment,KEGG pathway analysis and transcription factors,and key genes of drought resistance regulation were preliminarily explored.The expression of three candidate genes was analyzed by RT-qPCR.The results showed that there were 2 519 differentially expressed genes in the A90 treated with 20% PEG-6000 for 3,6,24 h compared with the control,and these genes were mainly enriched in plant hormone signal transduction,glutathione metabolism,phenylpropanoid biosynthesis,pentose and glucuronate interconversions and other drought-related processes.In addition,among 340 codifferentially expressed genes significantly enriched in the pathway,53 genes were annotated to 15 transcription factor families including RLKs,AP2/ERF and Tify.Among which StST/K1,StERF1 and StTify1 had higher expression levels,which might be key genes in drought resistance regulation.StST/K1 and StERF1 were mainly up-regulated in roots and leaves under drought and low temperature stress,StERF1 was up-regulated in roots,stems and leaves under salt stress.StTify1 was up-regulated in stems and leaves of the material under drought,and it was up-regulated in roots,stems and leaves under salt stress.But it was down-regulated only in stems of the material under low temperature stress.These results indicate that the three selected genes can respond to drought,salt and low temperature stress,it can provide a theoretical basis for study on drought resistance candidate genes in potato molecular breeding in the future.

In order to explore the important role of SBP1(S-RNase-binding protein 1)gene in plant self-incompatibility,a diploid wild potato was used as the material to obtain the full-length cDNA sequence of potato SpSBP1 (GenBank: MZ803088)by using RT-PCR cloning technique,and performed bioinformatics analysis and CRISPR/Cas9 vector construction for SpSBP1 gene.The results showed that the full length cDNA of SpSBP1 gene was 1 176 bp,containing 92 bp 5' non-coding region and 163 bp 3' non-coding region.The maximum open reading frame(ORF)of SpSBP1 gene was 921 bp,which encoding 306 amino acids.Protein domain analysis showed that SpSPB1 protein included Smc superfamily domain,RING finger domain and Zinc finger domain.The homologous sequence alignment and phylogenetic tree analysis showed that SpSBP1 had the highest homology with S.chacoense,followed by Nicotiana alata.Bioinformatics analysis showed that the molecular weight of SpSBP1 was 34.731 44 ku,with a theoretical isoelectric point of 5.10,and it was speculated that SpSBP1 was an acid unstable hydrophilic protein. The secondary structure predicted that the protein was mainly composed of α helix and random curling. And the protein was a non-secretory protein and had no transmembrane structure. SpSBP1 gene was cloned from wild diploid potato,and CRISPR/Cas9 vector was successfully constructed,and also the genetic transformation was carried out.

In order to clarify the genetic differences of the six new-colored potato strains NNCS-1,NNCS-5,NNCS-6,NNCS-7,NNCS-33 and NNCS-37 at the cytogenetic and DNA molecular level,this experiment used material MIN-021 as control,and the regular staining and slides preparing and SSR marker technology were used to analyze the pollen fertility,chromosome configuration at meiosis metaphase Ⅰ of pollen mother cells and SSR polymorphism of the above six varieties.The results shaved that the pollen fertility of the six new-colored potato strains were 44.00%,66.78%,74.44%,60.70%,78.10% and 80.22%,respectively.And the chromosome pairing configurations of these test materials were 8.45Ⅰ+6.09Ⅱ+7.35Ⅲ+1.33Ⅳ,6.91Ⅰ+7.13Ⅱ+5.73Ⅲ+2.41Ⅳ,5.19Ⅰ+9.16Ⅱ+4.51Ⅲ+2.74Ⅳ,6.55Ⅰ+8.35Ⅱ+4.97Ⅲ+2.46Ⅳ,4.02Ⅰ+10.15Ⅱ+3.40Ⅲ+3.37Ⅳ and 3.31Ⅰ+10.42Ⅱ+2.99Ⅲ+3.72Ⅳ,respectively,indicating that there were certain differences among the strains at the cytological level.Ten suitable SSR primers were selected to amplify the genomic DNA of each new strain and control material,and 151 SSR polymorphic sites were obtained,accounting for 86.78% of the total number of polymorphic loci.The genetic differences among the materials were revealed.In addition,a SSR fingerprint was amplified with the selected specific primers C42,which could identify six new-colored potato strains and control.Based on the average genetic distance(GD=0.62),the seven materials were divided into three categories: the new strain NNCS-37,NNCS-6,NNCS-7,NNCS-5 and the control(MIN-021)belong to one categorie.The new strains NNCS-33 and NNCS-1 were separately classified as a categorie.

To investigate the effect of different field water capacity on potato root growth and improve potato yield in the Northwest. The potato variety Hermes was grown in the field under a rain shelter and film mulching with drip irrigation under six field water capacity gradient treatments(85%-95%,75%-85%,65%-75%,55%-65%,45%-55% and non-irrigation)in 2018 to investigate the effects of different field water capacity on root system characteristics,tuber yield and relevance. The results showed that the root distribution gradually deepened as the field water holding capacity decreased,and when the field water holding capacity was greater than 45%,the roots were mainly distributed at 0-10 cm of the monopoly surface;when the field water holding capacity was less than 45%,the roots were mainly distributed at 20-40 cm of the monopoly side. Tuber yield and large potato rate were higher under the field water capacity of 65%-95% than that under other treatment,and the compensation effect was significant(P<0.05). Among them,the field water capacity of 75%-85% treatment had the highest yield,with an average yield of 884.06 g/plant,which was 257.61% higher than the T6 treatment. Correlation analysis revealed that field water capacity was significantly(P<0.05)positively correlated with top root length,root surface area,large potato rate and tuber yield,and top root length and surface area were significantly(P<0.05)positively correlated with potato tuber yield. In summary,field water capacity greater than 65% significantly increased root length,root surface area and yield on the monopoly surface,with the highest yields achieved under the 75%-85% water capacity treatment.

In order to study the molecular mechanism of sodium silicate enhancing risistance of potato to Rhizoctonia solani,a gene StWRKY11 with high expression level in potato transcriptome induced by sodium silicate was cloned and its bioinformatics was analysed.Total RNA was extracted from potato,amplified by RT-PCR and cloned.Through bioinformatics related software,the structure prediction and prediction analysis were carried out.The results showed that StWRKY11 gene with a open reading frame of 1 005 bp was cloned from potato Atlantic,encoding 334 amino acids.The molecular formula of the expressed protein was C₃₀₁₃H₅₀₂₃N₁₀₀₅O₁₂₆₀S₁₉₉,the molecular weight was 81.867 94 ku,the theoretical isoelectric point(pI)was 5.09,and the total number of atoms was 10 500.The expressed protein contained a typical WRKYGQK conserved domain,and the zinc finger structure was CX₅CX₂₃HXH,belonging to the second Ⅱ d subfamily.The secondary structural elements were α-helix,extended chain,β-folding and random coiling,among which the proportion of random curl was the highest,up to 61.68%.There were 29 phosphorylation sites in total,which might be located in the nucleus.There were cis-regulatory elements upstream of the promoter that might related to resistance stress response and cis-regulatory elements related to growth and development and hormone response.The gene was closely related to potato StWRKY5 gene,and the amino acid homology of the coding protein reached 95%.

A multiplex RT-PCR detection system was established and studied to target four sweet potato RNA viruses,Sweet potato feathery mottle virus (SPFMV),Sweet potato chlorotic stunt virus (SPCSV), Sweet potato virus G (SPVG)and Sweet potato virus C (SPVC),which caused serious damage in sweet potato production. Firstly,the specific primers for four viruses were designed by Premier 5.0 software and synthesized according to the conserved sequences of coat protein(CP)gene of these viruses from GenBank. The cDNA synthesized was used as a template,and 4 couples of selected primers were used simultaneously to amplify the target fragments by PCR. A best multiplex RT-PCR reaction system was tested by optimizing the annealing temperature,extension time,dNTPs amount,template amount,primer concentration and so on and an optimal quadruple RT-PCR system that could simultaneously detect these four sweet potato RNA viruses was established. The results showed that an accurate and sensitive multiplex RT-PCR method for detecting the four sweet potato viruses mentioned above with respective target band had been successfully established by challenge tests in which there would be no crossover among the virus primers. The multiplex RT-PCR method established in this study could detect four kinds of sweet potato virus at the same time. It was not only accurate and sensitive,but also reduced the cost of detection and improved the efficiency of virus detection.

The purpose was to prepare polyclonal antibody against the recombinant double CP of Potato leafroll virus (PLRV)and Potato virus S (PVS),and apply the polyclonal antibody to indirect ELISA and DAS-ELISA detections of PLRV and PVS.Prokaryotic expression vector pET22b-LRCP/SCP of the fused double CP gene of PLRV and PVS was constructed.After replacement of lysozyme treatment by ultrasonic disruption,inclusion body protein was extracted from the recombinant strain BL21(pET22b-LRCP/SCP),the target protein(recombinant double CP)was purified by nickel ion affinity chromatography and high-purity target protein of 51.2 ku was obtained.The high-purity recombinant double CP was used as antigen to immunize rabbits to prepare an antiserum with a titer of 1∶128 k.Specific reactions were respectively observed between the purified polyclonal antibody (IgG) against the recombinant double CP and the positive standard of PLRV or PVS and no cross-reaction was found between the purified IgG and other four potato major viruses (PVX, PVY, PVA and PVM). The purified IgG against the recombinant CP with the diluted concentration of 1∶3 200 still positively reacted with PLRV or PVS in indirect ELISA detection.The purified IgG and the alkaline phosphatase-conjugated IgG both with the diluted contraction of 1∶100 also positively reacted with PLRV or PVS positive standard in DAS-ELISA detection.The results showed that one type of the prepared IgG against the recombinant double CP could detect two viruses of PLRV and PVS by DAS-ELISA or indirect ELISA.

Small GTPases Rabs is a kind of monomer GTP binding protein,which can act as a molecular switch involve in variety of physiological and biochemical reactions in plant cells. In order to explore the relationship between potato small G protein StRab5b and anthocyanin synthesis,the StRab5b gene was overexpressed in potato by Agrobacterium mediated genetic transformation,try to study the effects of StRab5b gene on anthocyanin content and PAL activity. The result showed that overexpression of StRab5b gene significantly increased the anthocyanin content in potato leaves,stems and tubers. Compared with the control,the anthocyanin content in leaves of transgenic potatoes StRab5b-L2,StRab5b-L3 and StRab5b-L5 increased by 42%,24% and 54%,respectively;in stems was increased by 59%,37% and 32%,respectively;in tubers was increased by 118%,82% and 105%,respectively. At the same time,StRab5b gene also promoted the PAL activity,a key enzyme of plant anthocyanin synthesis. Compared with the control,the PAL activity in leaves of transgenic potatoes StRab5b-L2,StRab5b-L3 and StRab5b-L5 increased by 88%,63% and 66%,respectively;in stems increased by 48%,38% and 31%,respectively;in tubers increased by 98%,78% and 64%,respectively. In summary,small GTPases StRab5b increased the content of anthocyanin in potato by regulating PAL activity.

In this study,the transcription level of resistance genes to the infection of Colletotrichum gloeosporioides were explored at the molecular level and provided candidate genes for further study of disease resistance mechanism.Suyu 8 is a new yam variety highly resistant to anthracnose,which was bred by tissue culture mutagenesis of the highly susceptible strain 024.In order to find out the anthracnose resistance genes,Suyu 8 and strain 024 leaves were inoculated for different time by Colletotrichum gloeosporioides strain 4-2,the differentially expressed genes were analyzed by transcriptome sequencing.Concurrently,the uninoculation leaves of Suyu 8 were used as control.The number of differentially expressed genes,inoculation for 24,48,72,96 h,were 197,132,187 and 313,respectively.After removing the common differentially expressed genes at each time point,we obtained 711 differentially expressed genes.Go enrichment showed that the differential genes were mainly related to response to biological stimulation,defense response,cell wall metabolism and oxidation-reduction process.KEGG enrichment analysis revealed that many metabolic pathways related to plant disease resistance were changed.The expression of multiple genes varied which defense-related plant hormone signal transduction pathways,such as auxin,jasmonic acid,and ethylene.Among them,five early auxin-responsive genes,the key genes of jasmonic acid and abscisic acid biosynthesis were up-regulated,while ERF036 was down-regulated,which might negatively regulate the infection of Colletotrichum gloeosporioides.Several cytochrome P450 genes,ubiquitin ligases involved secondary metabolite modification and phytosterol synthetases,defensins and lectins were up-regulated.WRKY,MYB and TIFY transcription factors positively or negatively regulate the expression of disease resistance genes.Under the regulation of transcription factors,PR protein,NBS-LRR disease resistance genes,receptor kinases were highly expressed,the expressions of CAT and SOD genes of antioxidant protective enzyme systems were activated by reactive oxygen species.In addition,the enzymes related to starch and sucrose synthesis were up-regulated,and enzymes related to starch degradation were down regulated.The expression trends of LAX4,IAA4,IAA21 were consistent with that of transcriptome sequencing.The relative expression of LAX4,IAA4 and IAA21 in resistant varieties were significantly higher than susceptible varieties,suggesting that auxin signaling pathway is beneficial to the immune response to anthracnose for yam.

The aim of this research was to clone IPT(Isopentenyl transferase,IPT ) genes in yam,predict the structure and property of DoIPT proteins and identify the expression of DoIPTs during bulbil sprouting.DoIPTs were cloned by homologous cloning techniques.The structure and property of DoIPT proteins were predicted by bioinformatics analysis.Real-time PCR technique was applied to identify the expression of these genes.Three nucleic acid sequences of 1 398,1 044,1 349 bp were obtained from yam.The three sequences were named DoIPT1,DoIPT5a and DoIPT5b,and the registration numbers of these genes were MW353160,MW353016 and MW353017,respectively.The reading frame lengths were 1 137,861,1 011 bp respectively,and the encoded amino acid lengths were 378,286,336 aa,respectively.Bioinformatics analysis showed that DoIPTs were unstable,hydrophilic and external family proteins.There were two signal peptides in DoIPT5b,and no signal peptide was found in the other two proteins.The secondary structures in the three proteins were consistent with the prediction models of the tertiary structures of three genes.The encoded regions of DoIPTs had high similarity with the isopentenyl transferase protein of other plants.Coding areas of DoIPTs showed that the N-terminal regions of DoIPTs contained the P-loop NTPase structural domain GXXGXGKS(T),which was able to catalyse cytokinin synthesis.The results of Real-time PCR technique showed that the expression of DoIPT5a in sprouting bulbils was highest under the condition of water shortage at 22 ℃;and the expression of DoIPT1 and DoIPT5b genes was the highest in a humid environment;the expression of DOIPTs genes raised with paclobutrazol treatment.These results laid a foundation for further study on the function of DoIPTs in yam.

In order to explore the effects of different concentrations of exogenous melatonin on the growth of potato seedlings under low temperature stress after cold acclimation,using Yunnan main potato variety Hezuo 88 as material,the effects of different concentrations of exogenous melatonin(50,100,150 μmol/L)on the growth and active oxygen metabolism system of potato seedlings under low temperature stress(4 ℃ 14 d ,-2 ℃ 12 h)were studied.The purpose of this study was to explore the feasibility of exogenous MT in alleviating the injury of potato seedlings caused by low temperature stress.The results showed that compared with potato seedlings under low temperature stress,the survival rate of seedlings treated with 50 μmol/L MT increased by 38.89 percentage point,and the plant height and stem diameter increased by 2.92% and 1.86%,the contents of SS,SP and Pro increased by 12.66%,13.80% and 1.96%,the activities of POD and CAT increased by 29.24% and 351.62%.The plant height and stem diameter of seedlings treated with 100 μmol/L MT increased by 16.97% and 2.82%,the contents of MDA and H₂O₂ decreased by 19.35% and 0.48%,the activities of POD and CAT increased by 55.44% and 213.56%.The survival rate of seedlings treated with 150 μmol/L MT increased by 27.78 percentage point,the plant height and stem diameter increased by 5.62% and 13.20%,the content of MDA decreased by 9.45%,the content of Pro increased by 38.70%,SOD,POD and CAT activity increased by 52.61%,25.25% and 300.94%,and the content of AsA and GSH increased by 3.48% and 3.97%.The results showed that exogenous MT could promote the growth of potato seedlings,reduce the content of MDA and H₂O₂ in leaves,promote the accumulation of SS,SP and Pro,increase the activities of SOD,POD and CAT,and increase the content of AsA and GSH.Thus,it can alleviate the damage of low temperature stress to potato seedlings,and then improve the ability of potato seedlings to resist low temperature stress.In summary,50 μmol/L MT treatment could better improve the stress resistance of potato seedlings under low temperature stress.

This article aims to explore the control methods of sweetpotato storage and provide a theoretical basis for regulating sweetpotato storage.Pre-production regulation is an important part of sweetpotato storage regulation, and fertilization is one of the important means of pre-production regulation. This study starts with fertilizer and uses two varieties of Shangshu 19 and Xinxiang as experimental materials. Nitrogen and phosphate fertilizers, and applying different gradients of potassium fertilizer. After uniform harvesting, select sweetpotatoes with the same size and no damage, and store them in a cold storage at 14℃ and 85% humidity. Samples were taken during the storage period of 0, 15, 30, 60, 90 days, and the decay rate, cell wall composition and enzyme activity were measured respectively, so as to explore the effect of different potassium application on the decay rate, cell wall composition and degrading enzymes of sweetpotato. The results of the study showed that the sweetpotatoes with different potassium application rates showed different degrees of decay during storage. Among them, the potassium application rate of Shangshu 19 was 150 kg/ha(Shangshu 19 K₂)and the potassium application rate of Xinxiang was 225 kg/ha(Xinxiang K₃), which had better storability and the lowest rot rate. Respectively, 18.25% and 23.00%, and Shangshu 19 K₂ had a higher cellulose content, which was as high as 80.63 mg/g, the original pectin content of Xinxiang K₃ is significantly higher than other treatments, with an average of up to 1.14%, and β-Gal enzyme activity is significantly lower than other treatments. Applying potassium treatment to sweetpotato can slow down the degradation of sweetpotato cell wall components and improve the ability to maintain the integrity of the cell wall, thereby reducing the rate of decay.

In order to reveal the response relationship between potato yield and rhizosphere soil microbiological characteristics under plastic film mulching and supplementary irrigation technology in semi-arid area,field experiments of potato mulching and supplementary irrigation were carried out in Dingxi irrigation experimental station of Gansu Province,which included six treatments,drip irrigation under plastic film(PFID),drip irrigation under semi mulching(PHID),furrow irrigation with full film mulching(PFIF),furrow irrigation without film mulching(PNIF),border irrigation with plastic film mulching(PFIB),and no irrigation in border field covered with plastic film(PFIBN).Flat planting without film and no irrigation(PNIN) was used as control.The effects of different treatments on potato yield,rhizosphere soil organic matter(TOM),organic carbon(TOC),microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),urease and catalase were analyzed.The results showed that mulching methods had significant effects on rhizosphere soil microbiological properties under drip irrigation and furrow irrigation.MBC and MBN of full film mulching treatment were significantly higher than that of half mulching treatment,while urease and catalase activities of semi mulching or no mulching treatment were significantly higher than that of full mulching treatment(P <0.05).On the other hand,the activity of urease and catalase of all supplementary irrigation treatments(PFID,PHID,PFIF,PNIF,PFIB) were significantly higher than control treatment(PNIN).The potato yield,number of tubers per plant and tuber weight per plant of supplemental irrigation treatment were also significantly higher than control treatment.In particular,the yield of semi mulched drip irrigation treatment(PHID) was 44 603.70 kg/ha,which was 51.00% higher than control.Correlation analysis showed that potato yield was highly significant correlated with MBC,urease activity and catalase(P <0.01),and positively correlated with TOM and TOC(P <0.05).

In order to clarify the diversity and differences of endophytic bacteria in leaves of different potato varieties and provide basis for studying the mechanism of potato stress tolerance and the development of endophytic bacteria.The endophytic bacteria from the leaves of four main potato varieties in Yunnan Province were isolated and cultured on LB medium,all those strains were identified based on the morphological characteristics and the 16S rDNA sequence.There were 10 species of endophytic bacteria belonging to 9 genera,8 families and 3 phyla were isolated from Qingshu No.9 leaves. Staphylococcus and Exiguobacterium were the dominant genera,and the relative abundance of both genera were 18.18%.There were 12 species of endophytic bacteria belonging to 11 genera,11 families and 4 phyla were isolated from Hui-2 leaves. Acinetobacter and Pseudomonas were the dominant genera,and the relative abundance of both genera were 15.38%.There were 13 species of endophytic bacteria belonging to 10 genera,9 families and 4 phyla were isolated from Hezuo No.88 leaves. Acinetobacter were the dominant genera,with a relative abundance of 23.53%.There were 17 species of endophytic bacteria belonging to 8 genera,7 families and 4 phyla were isolated from Lishu No.6 leaves. Staphylococcus were the dominant genera,with a relative abundance of 22.22%.There were 37 species of culturable bacteria were isolated from the leaves of four potato varieties.There were 4,8,4,10 unique endophytic bacteria from the leaves of Qingshu No.9,Hui-2,Hezuo No.88 and Lishu No.6,respectively.The species composition and dominant genera of endophytic bacteria in leaves of different potato varieties were different,the results would provide bacteria resources for studying the function of endophytic bacteria in potato leaves.

In order to study the molecular mechanism of purple sweet potato leaf in response to enhanced UV-B radiation, the leaf of Dianziganshu 24(DZS24) was used as the test material and transcriptome sequencing analysis was performed by high-throughput sequencing technology under natural light and artificial supplementary the UV-B(T=7.2 kJ/(m² · d)). The results showed that the expression of 477 genes(DEGs) were changed significantly, among which 382 and 95 were up-and down-regulated ones. GO analysis showed that these DEGs were mainly significantly enriched in oxidation-reduction process of biological process and oxidoreductase activity of molecular function. KEGG pathway analysis showed that a total of 9 pathways were significantly enriched, among which the biosynthesis pathway of secondary metabolites contained the largest number of DEGs. The DEGs of purple sweet potato leaf in response to enhanced the UV-B were mainly CHS (Tai6.1732, Tai6.53503, Tai6.45381) and DFR (Tai6.3019) in the flavonoid synthesis pathway as well as the CYP83B1 (Tai6.44115, Tai6.18064, Tai6.41206) in the glucosinolate biosynthesis and CYP85A1 (Tai6.2806, Tai6.19253, Tai6.15801) in brassinosteroid biosynthesis. The main transcription factors were C2H2, NAM, bHLH and RR-A-type. In summary, the key genes might be IbCHS, IbDFR, IbCYP83B1 and IbCYP85A1, as well as the main transcription factors might be C2H2, NAM, bHLH and RR-A-type in the purple sweet potato leaf response to the UV-B enhancement.

Enhanced UV-B radiation can cause damage to plants, and melatonin can enhance plant resistance. At present, there is no research report on the effect of melatonin on potatoes under UV-B radiation, so this experiment measured plant height, photosynthetic parameters(Pn, Gs, Ci, and Tr), fluorescence parameters(Fv/Fm, ETR, qP, and NPQ), 1, 5-bisphosphate ribulose carboxylase(Rubisco) and phosphoenolpyruvate carboxylase(PEPC), to analyze the effect of melatonin on the photosynthetic and fluorescence characteristics of potatoes under UV-B radiation, provide scientific basis for revealing the defense mechanism of melatonin against potato plants under UV-B radiation. The potato variety Hezuo 88 planted in greenhouse was used as experimental material. The concentrations of melatonin were set at 0, 25, 50, 100, 150, 200 μmol/L respectively under natural light(CK) and three enhanced UV-B radiation((2.5, 5.0, 7.5 KJ/(m²·d)).The plant height, Rubisco, PEPC, photosynthetic parameters and fluorescence parameters (except NPQ) of potato decreased after exposure to enhanced UV-B radiation, but increased after exposure to melatonin.Melatonin can improve the resistance of potato to UV-B radiation, increase the plant height and enhance its photosynthetic capacity. However, the trend of these indicators rising first and then decreasing also indicates that excessive melatonin concentration will also cause certain damage to plants.

In order to obtain potato plants which could be resistant to multiple viruses (viroid) simultaneously, P25, HC-Pro, and Virp1 gene targeting PVX, PVY, and PSTVd proteins were cloned, respectively. Three types of amiRNAs targeting sequences encoding the silencing suppressor P25, HC-Pro and Virp1 were designed by using Arabidopsis thaliana miR159a as backbone. These three amiRNA sequences were connected by Overlapping PCR. The synthetic of P25, HC-Pro and Virp1 gene was inserted into the expression vector pCAMBIA1300-221 to form p1300-221-preamiR-P25-HCPro-Virp1, and the vector was verified by PCR and restriction enzyme digestion. Pre-amiR-P25-HCPro-Virp1 was transformed into minituber of potato cultivar Favorita by Agrobacterium tumefaciens infection. 15 transformed plants were obtained through regenerating, pressure screening and differentiation.PCR results showed that 10 of them were detected the same size fragment (729 bp) as the target gene. Further qRT-PCR testing confirmed that amiR-P25-HCPro-Virp1 gene was expressed in 10 transformed plants, and the relative expression was between 7.68-21.37. Inoculated the T₀ transgenic plants with the mixture virus of PVX, PVY and PSTVd by friction into the leaves of the plants at the 6-8 leaf stage. The plant growth was observed after 20 days and the results showed that the control plants were severely susceptible, with symptoms such as short plants and mottled leaves, while the transformed plants did not show infection symptoms, and growth normally. There was no virus detected by RT-PCR either. This indicated that the transfected amiR-P25-HCPro-Virp could be stably expressed in the transformed plants, and the transformed plants were resistant to PVX, PVY and PVSTd viruses (viroid). Transformed plants resistant to PVX, PVY and PVSTd were obtained, and the resistance was significant, which provided new genetic resources for potato virus-resistant breeding.

In order to investigate the function of StTCP13 in salt stress and lay the foundation for the functional study of StTCP13 in response to abiotic stress of potato. The coding sequence of StTCP13 was obtained by homologous cloning. The protein domain and phylogenetic tree were analyzed by bioinformatics.The results showed that the StTCP13 gene was cloned from the potato variety Favorita.The coding sequence length of StTCP13 was 669 bp, encoding a protein composed of 222 amino acid residues.The results of prokaryotic expression suggested that the molecular weight of fusion protein was 51 ku.Protein domain analysis suggested that the protein contained a conserved TCP domain.The results of phylogenetic tree revealed that the protein had a high homology with the TCP13 in Solanum pennellii and Capsicum annuum.Expression pattern of StTCP13 was analyzed by qRT-PCR.Expression analysis showed that the StTCP13 exhibited different expression levels in root, stem, leaf, bud and bud eye in potato. The StTCP13 had high expression level in root, low expression level in bud eye, in addition,the FPKM of StTCP13 in Spud DB showed that the expression of StTCP13 was induced by high-salinity, drought and ABA treatments.The StTCP13-pGEX6P1 prokaryotic expression vector was constructed by double enzyme digestion. Prokaryotic expression results showed that the StTCP13-GST tag fusion protein was successfully expressed in Escherichia coli BL21 . Salt stress phenotype analysis suggested that StTCP13 could improve the tolerance to salt stress in E.coli BL21 . Above all, the StTCP13 might play a role in response to salt stress in potato.

In order to determine the difference of molecular and cellular genetics of six new potato strains (NNS-P 11, NNS-H 6,NNS-H 4, NNS-C 10, NNS-L 9 and NNS-Y 40), with MIN-021 as control material, conventional compression and SSR molecular labeling were used to compare and analyze the traits of the six new strains, include pollen fertility, PMCMⅠ chromosome pairing behavior, SSR fingerprint characteristics. This would provide the basis for further breeding, identification and registration of new potato varieties. The results showed that:There were some differences in pollen fertility among six new potato strains. The new strain NNS-Y 40 had the lowest pollen fertility (39.95%), the new strains NNS-P 11, NNS-H 4, NNS-C 10 had the highest pollen fertility (81.12%, 77.94%, 77.76%), the new strains NNS-H 6 and NNS-L 9 pollen fertility in the middle of the lowest and highest (67.27%, 69.71%). The chromosome pairing configuration of six new strains NNS-P 11, NNS-H 6, NNS-H 4, NNS-C 10, NNS-L 9 and NNS-Y 40 were 1.08Ⅰ+14.89Ⅱ+1.18Ⅲ+3.4 0Ⅳ, 2.35Ⅰ+11.96Ⅱ+3.59Ⅲ+2.74Ⅳ, 2.10Ⅰ+14.21Ⅱ+1.35Ⅲ+3.02Ⅳ, 3.31Ⅰ+13.98Ⅱ+2.99Ⅲ+1.94Ⅳ, 3.45Ⅰ+12.94Ⅱ+2.81Ⅲ+2.56Ⅳ and 8.23Ⅰ+6.92Ⅱ+6.07Ⅲ+1.93Ⅳ. The genomic DNA of six potato strains and control sample was amplified with 10 pairs SSR selected primers and 82 polymorphic bands were obtained, with the polymorphic ratio was 78.10%. The genetic distance (GD) of new potato strains ranged from 0.244 4-0.687 5. Base on 0.40 genetic distance, seven test materials were divided into three categories:the first category was new strains NNS-P 11, NNS-L 9, NNS-Y 40 and MIN-021, the second category was new strain NNS-H 6 and NNS-H 4, and the third category was new strain NNS-C 10. In addition, a SSR fingerprint was established to distinguish 7 test materials.

In order to explore the function of StWRKY57 (PGSC0003DMT400072958) in potato, a full-length cDNA sequence of the homologous StWRKY57 gene in Solanum tuberosum PB06 named StWRKY57-PB was cloned by RT-PCR and bioinformatics methods were used to analyze the sequence characteristic of StWRKY57-PB. For prokaryotic expression and purify, the prokaryotic expression vector of StWRKY57-PB was constructed based on pGEX-KG, then fusion protein was induced in Escherichia coli strains. The results showed that the StWRKY57-PB gene contained a 981 bp open reading frame(ORF), and the coding protein belonged to the Ⅱ c class of the WRKY transcription factor family, containing 326 amino acid residues with a WRKY(WRKYGQK) domain and a zinc-finger-like motif(C-X₄-C-X₂₃-H-X₁-H). StWRKY57-PB was determined structurally to be 16.56% a-helix, 13.50% extended strand, 7.98% β-turn and 61.96% random coil. Compared with StWRKY57(XP_006348711.1), there were 4 amino acid mutations in StWRKY57-PB. Multiple alignment and phylogenetic tree analyses indicated that StWRKY57-PB showed the next-closest relationship with SlWRKY57 with 93% similarity and was farthest to AtWRKY57. StWRKY57-PB protein was stably expressed in three Escherichia coli strains of Rosetta, BL21 and Tuner with 0.5 mmol/L IPTG. Fusion protein of GST-StWRKY57-PB was purified through GST SefiroseTM resin, and then Western Blot was carried to verify the successful expression and purification of the protein. It is of great significance to further determine the activity and biological function of this protein in vitro.

In order to reveal the genetic diversity of sweet potato and its wild species and analyze the genetic relationship between sweet potato and its wild species, SCoT molecular markers were used to analyze the results of PCR amplification, genetic diversity, evolutionary relationship and population structure of 22 germplasm of sweetpotato and its wild species I.trifida and I.triloba in the present study. The results showed that 278 stable bands were detected by 43 primers, 4-12 bands could be detected by each primer, and five primers with rich polymorphism were screened, which were SCoT-8, SCoT-20, SCoT-26, SCoT-36 and SCoT-35. These primers could be used in the study of sweet potato molecular markers in the future. The analysis of genetic diversity based on the results of molecular markers showed that the highest genetic diversity was in I.trifida, followed by I.batatas, and the lowest in I.triloba. According to the results of genetic cluster analysis and population genetic structure analysis, 22 germplasm were divided into three groups, and the classification of each group was basically the same as its species. There was less blood exchange between different species, and the genetic composition was relatively simple. In comparison, the blood exchange between sweet potato and I.trifida was more than that between I.triloba. In conclusion, the results of this study preliminarily proved the potential application of SCoT molecular markers in the study of sweet potato evolution, and revealed the different genetic relationships between sweet potato and its wild relatives, which provided theoretical support for introducing I. trifida and other wild species into sweet potato breeding to improve the genetic diversity of sweet potato in the future.

In order to further clarify the spatial and temporal accumulation characteristics of cadmium in sweetpotato and to explore the causes of low cadmium accumulation in fleshed storage root,the temporal and spatial differences of cadmium accumulation in Xiangshu 20 were detected by atomic absorption spectrometry(AAS)in this study,and the expression difference of homologous genes related to cadmium accumulation in sweetpotato were analyzed by Fluorescence quantitative PCR.The results showed that the cadmium accumulation of sweetpotato followed the characteristics of root>stem>leaf. When plants were growth in the soil with 0.6 mg/kg cadmium,the increase rate of cadmium concentration in sweetpotato range from 3.05 to 8.75,and when plants growth in the soil with 2.0 mg/kg cadmium,the increase rate of cadmium concentration in sweetpotato range from 6.25 to 26.89. The accumulation rate of cadmium in shoots and leaves was higher than that in fleshed storage roots. The cadmium accumulated in leaves was not easy to transfer again,so cadmium concentration in new leaves was lower than that in old leaves. The homologous genes related to plant cadmium accumulation and transport existed in sweetpotato genome,and most of them had multiple homologous copies. Although these genes were induced to express with the increase of cadmium accumulation in plants,the spatiotemporal expression patterns of these genes were different. Compared with the expression pattern of genes related to cadmium accumulation,the expression of cadmium stress response related genes was been induced by cadmium accumulation more obvious. The cadmium accumulation in sweetpotato increased with the increase of soil cadmium concentration,and increased with the extension of growth time. The accumulation of cadmium in fleshed storage roots was lower than that in peels,stems and leaves,and the accumulation rate of cadmium in fleshed storage roots were much lower than that in shoots with the extension of growth time. The homologous genes related to plant cadmium accumulation and transport existed in sweetpotato genome,and most of them had multiple homologous copies. The spatiotemporal expression patterns of these genes were different,it was suggested that this expression difference was related to the cadmium accumulation characteristics of sweetpotato.

To identify and characterize the species of Streptomyces causing potato common scab in Shandong Gaomi. The typical scabby tubers were collected from potato growing areas in Shandong Gaomi from 2018 to 2019. After isolating and purifying,178 Streptomyces strains were obtained from scabby tubers. The pathogenicity of the isolates was determined on tuber slices,radish seedlings method and Koch's rule in greenhouse. A total of 178 strains were screened as pathogenic strains and could induce typical scab symptoms on immature potato. In addition,the potato scab strains isolated in 5 areas of Gaomi City were subjected to morphological identification,PCR molecular identification and pathogenic gene detection. These pathogenic strains were identified and phylogenetic tree was constructed on the basis of the differences in 16S rDNA sequences. Results revealed four kinds of Streptomyces species were found in Gaomi City,Shandong Province,including Streptomyces acidiscabies, Streptomyces scabies, Streptomyces luridiscabiei and Streptomyces griseoaurantiacus, which were consistent with the cluster analysis results. Among them, Streptomyces acidiscabies are dominant species and Streptomyces griseoaurantiacus are newly discovered common scab pathogens in China. The results suggestd that the Streptomyces species causing potato scab had obvious composition diversity and distribution complexity in Shandong Gaomi.

In order to identify PVS and its individual strains accurately and quickly, and understand the content of PVS in potato leaves, petioles, stems, roots and dormant tubers, which is helpful for selecting suitable detection sites, an Reverse transcription-qPCR (RT-qPCR) was developed by designing a pair of universal primer, and PVS^O and PVS^A strains were identified using melting curve. The specificity of the system was evaluated with Potato virus X (PVX), Potato virus Y (PVY), Potato virus M (PVM), Potato virus A (PVA) and Potato leafroll virus (PLRV) positive samples. The standard curve of PVS^O and PVS^A were established with PVS^O and PVS^A standard recombinant plasmid, and the contents of PVS^O and PVS^A in potato leaves, petioles, stems, roots and dormant tubers of potato varieties Youjin and Jizhangshu 12 inoculated with PVS^O and PVS^A were detected. Moreover, ninety positive samples collected from the 11 Provinces (municipality or autonomous region) were verified by the RT-qPCR system. The amplification of PVS^O and PVS^A strains showed specific peak at 85.77-86.00℃ and 87.78-87.91℃, respectively, in melting curve analysis, but no cross-reaction was found for PVX, PVY, PVM, PVA and PLRV samples. When the concentration of PVS^O and PVS^A recombinant plasmid were from 1.09×10⁵-1.09×10⁹ copies/μL and 1.26×10⁵-1.26×10⁹ copies/μL, respectively, there was a good linear relationship between the standard curve circulation threshold (Ct) and the log value of PVS virus particles, with determination coefficient being 0.994 2 and 0.991 2, respectively. The content of PVS^O and PVS^A in five parts of potato tissues were over 10⁷, and all of them could be detected, with the content of PVS^O being the highest in petioles. Ninety PVS positive samples from 11 Provinces (municipality or autonomous region) were detected effectively. The PVS RT-qPCR detection system established was fast, accurate and specific and PVS^O and PVS^A strains could be identified by specific peak in melting curve. The five parts of tissue including leaves, petioles, stems, roots and dormant tubers could be used for detection, with the advantage of good practicability. This research provides technical support to produce virus-free seed potatoes.

The roots of potato plants were treated with phosphoric acid solution (pH 4) for 4 d,then four stages of stolons were collected as samples, which were before stolon tip hook (stage Ⅰ), stolon tip hook (stage Ⅱ), swelling tips (stage Ⅲ) and initial tuber formation (stage Ⅳ). The samples were used to determine the expression levels of genes related to tuber formation. The 45-day-old plants treated with acid solution formed the maximum stolon at stage Ⅱ, and produced the largest quantity of tubers which were 53.2% and 74.5% higher than that of the 55 and 60-day-old plants. The expressions levels of StHd3a, StFD, StSUSY4, StHXK, StPIN1, StABA and StSP6A of acid treatment group were obviously higher than those of control group in all stages. Moreover, at the stolon development in acid treatment group of stage Ⅰ and stage Ⅱ, compared with the control group, the StGA expressions were significantly increased by 49.4% and 25.1%,the StAGL8 expressions were significantly increased by 119.7% and 140.1%, while the StAGPase expressions were significantly reduced by 60.1% and 41.7%, and the StSSS expressions were significantly reduced by 23.2% and 21.6%. However, the StCOL expressions in acid treated plants were not significantly different from that of the control grup. In conclusion, the acid treatment could affect the complex process of potato tuber formation through the regulation of the above tested genes (except StCOL) expression levels or patterns during the tuberization.

In this study, we set a series of different irrigation combinations. We systematically studied the effects of different irrigation time combinations on potato growth, yield formation and water use efficiency under drip irrigation. The total irrigation volume was 1 725 m³/ha, and the number of irrigation times was 7 times, the non-irrigation treatment was used as a control (CK), and four different irrigation periods are set respectively,B1 (irrigation 300 m³/ha on June 15th,irrigation 225 m³/ha on June 25th, irrigation 300 m³/ha on July 5th, irrigation 300 m³/ha on July 15th, irrigation 225 m³/ha on July 25th, irrigation 225 m³/ha on August 4th, irrigation 150 m³/ha on August 14th), B2 (irrigation 150 m³/ha on June 5th, irrigation 300 m³/ha on June 15th, irrigation 225 m³/ha on June 25th, irrigation 300 m³/ha on July 5th, irrigation 300 m³/ha on July 15th, irrigation 225m³/ha on July 25th, irrigation 225 m³/ha on August 4th), B3 (irrigation 150 m³/ha on June 5th,irrigation 300 m³/ha on June 15th, irrigation 300 m³/ha on July 5th, irrigation 300 m³/ha on July 15th, irrigation 225m³/ha on July 25th, irrigation 225 m³/ha on August 4th,irrigation 225 m³/ha on August 14th), B4 (irrigation 300 m³/ha on June 15th, irrigation 300 m³/ha on July 5th, irrigation 300 m³/ha on July 15th, irrigation 225 m³/ha on July 25th,irrigation 225 m³/ha on August 4th,irrigation 225 m³/ha on August 14th,irrigation 150 m³/ha on August 24th).The results showed that with the potato growth stage developed, the leaf area index, dry matter accumulation of leaves and petioles and stems were highest in B1 treatment, and all reached the maximum value at 65 days after emergence; the dry matter accumulation amount of tubers reached the maximum value during the harvest period, B1 treatment was extremely significantly higher than other treatments. The tuber yield and commercial potato rate of B1 treatment were the highest, reaching 53 246 kg/ha, 89.6%, which was not significantly different from other treatments, but the water use efficiency was significantly higher than other treatments.The starch content was highest in CK, and there was no significant difference between irrigation treatments. The Pro content and MDA content were the lowest in B1 treatment, significantly lower than CK. In summary, the B1 irrigation period treatment combination can be used as a suitable irrigation time combination for potato production under drip irrigation.

A plant expression vector pBI121 -StPR1 was constructed to clarify the role of potato StPR1 gene in disease resistance, and introduce StPR1 gene into tobacco by Agrobacterium transformation method. The disease resistance and physiological characteristics of transgenic tobacco were investigated using different pathogen treatment, including bacterial disease soft rot (E. carotovora subsp. Carotovora Borgey, Ecc; E. chrysanthemi Burkholder. Atroseptica Dye, Ech; E. carotovora subsp. Mc Fadden et Dimock, Eca), bacterial wilt (Ralstonia solanacearum, RS) and fungal disease dry rot (F. sambucinum, F. avenaceum). The results showed that the diameter of lesions leaves increased with the prolongation of stress time in transgenic tobacco and wild type (WT) under the pathogen stress, and the diameter of transgenic tobacco lesions were significantly smaller than WT. In the physiological characteristics analysis, the physiological indexes of leaves increased with the prolongation of stress time in WT and transgenic tobacco, but the activities of SOD, POD and CAT in transgenic tobacco were all increased to different degrees compared WT. The results of disease resistance and physiological characteristics showed that transgenic tobacco had stronger resistance to pathogenic bacteria and fungi, indicating that the StPR1 gene played an important role in the disease resistance of potato, which could provide a theoretical basis for PR1 gene resistance in plants.

In order to explore the possible functions of StBAG3 gene derived from potato in the process of potato resistance establishment, this study used the in vitro leaves of Shepody as experimental material, and used the transient expression system of potato to explore the preliminary function of StBAG3 gene. The results showed that Phytophthora infestans was inoculated on the leaves of potato expressing StBAG3 gene transiently, after 24, 48, 72, 96 h, the relative lesions area was significantly reduced by 1.92-39.15 percentage points compared with the control, indicating transient expression of the StBAG3 gene significantly increased potato resistance to Phytophthora infestans. This result was also confirmed by the staining of necrotic cells at the inoculation site. The results of qualitative and quantitative determination of H₂O₂ showed that the accumulation of H₂O₂ at the inoculation site after transient expression of StBAG3 gene was not significantly different from 0 to 48 h after inoculation, they significantly different from control at 72,96 h after inoculation, both reached the maximum at 72 h, 0.146, 0.086 μmol/g, respectively. The results of ROS scavenging enzymes activity assay showed that the activity of SOD and CAT enzymes were varied with the inoculation time after transient expression of StBAG3 gene, but both were higher than the control leaves at 0-96 h. POD activity was not significantly different from the control leaves at 0-72 h after inoculation, only significantly higher than control leaves at 96 h after inoculation. It was indirectly proved that H₂O₂ was involved in StBAG3 gene mediated positive regulation establishment process of potato resistance to late blight. The results showed that StBAG3 gene can increase potato resistance to late blight.

In order to investigate the relationship of nitrogen fertilizer(N) and planting density(D) with the yield, quality and starch pasting properties of fresh edible sweetpotato, the field experiments were carried out in 2017 and 2018 using Xushu 32 and Xuzishu 5 as the research subjects, and setting three nitrogen fertilizer levels and five planting densities. The results showed that:The storage root yield of the two varieties decreased with the increase of nitrogen application, while first decreased and then increased with the increase of density. In general, the maximum storage root yield came from the treatment of N0(0 kg/ha) nitrogen level and D1(43 785 plant/ha) density level; Nitrogen application reduced the dry matter rate and significantly increased the protein content in the two sweetpotato varieties. With the increase of planting density, the dry matter rate, starch content and protein content of the two cultivars generally increased first and then decreased. The reduced sugar showed a downward trend, while the soluble sugar content fluctuated, which was the lowest at D3 level; On the whole, the peak viscosity, hot paste viscosity and breakdown value of starch in the two varieties were significantly reduced and the setback value was significantly increased, resulting in the decline of cooking and eating quality. The peak viscosity, hot paste viscosity, breakdown value and cool paste viscosity fluctuated with the increase of density; the maximum values were from the D3 level for Xushu 32, and from the D2 level for Xuzishu 5. The effects of nitrogen application and planting density on RVA spectrum of sweetpotato starch were different among varieties and characteristics. Based on the results of this experiment, applying a large amount of nitrogen to a plot with high soil fertility reduced the storage root yield of sweetpotato, and negatively affected the nutritional quality and edible quality. At the density level of 43 785 plants/ha, the storage root yield was the highest. However, proper increase of density was beneficial to the improvement of nutritional quality, cooking quality and eating quality.

To study the effects of potato-oat intercropping and nitrogen application rates on agronomic traits and yield of potato and provide the theoretical basis for further study of nitrogen transport in intercropping system, a split zone design with three planting patterns(potato monocropping, oatmeal monocropping and potato-oat intercropping) and four nitrogen application levels(0, 75, 150, 225 kg/ha) were performed. The results showed that under the same planting pattern, the plant height, stem diameter, dry matter accumulation rate and chlorophyll(SPAD) of the nitrogen-treated potato showed a trend of increasing first and then decreasing with the promotion of growth period, and the effect of nitrogen application was higher than that of intercropping. Nitrogen application could significantly increase the potato yield compared to no nitrogen application. The increase amount of intercropping was greater than that of monocropping. The contribution of nitrogen application to yield was greater than that of intercropping. Compared with the control, the yield of monocropping nitrogen treatments increased by 1.73%, 10.29% and 3.97%, respectively, while the yield of intercropping nitrogen treatments increased by 8.68%, 31.23% and 15.33%, respectively. Under the interaction of nitrogen application level with intercropping planting mode, the difference of yield was significant(P<0.05). Without nitrogen application, the yield of intercropping was lower than that of monocropping, which might be caused by interspecific competition between the two crops. Under different nitrogen application levels, the land equivalent ratio(LER) of the intercropping system was greater than 1, the intercropping advantage was obvious, the interspecific competition of potato-oat intercropping was less than 0, the competitiveness of oats was stronger than that of potato, and the yield of potato was positively correlated with the number of tubers per hole, the quality of each potato and the number of big tuber. In general, planting patterns and nitrogen application levels had an impact on potato agronomic traits and yield, and the contribution of nitrogen application was higher than that of planting mode.

In order to study the changes of potassium content and other related physiological characteristics in tubers of different potato varieties at seedling stage with different potassium supply levels, field experiments were conducted to study Dongnong 310, Yanshu 4 and Zhongshu 5 at three potassium levels. The results showed that under the three levels of K₀, K₁ and K₂, the potassium content of tubers in different varieties was significantly different, and the potassium content of Dongnong 310 seedlings was much higher than that of Zhongshu 5 and Yanshu 4. Correlation between potassium content in potato and chlorophyll (SPAD), root activity (RV), malondialdehyde content (MDA), sucrose synthase (SS) and sucrose phosphate synthase (SPS) under low potassium and high potassium conditions analysis, when the potassium level is low, root activity and related enzyme activity become the limiting factors affecting potassium content; while under high potassium conditions, potassium content is positively correlated with SPAD, but negatively correlated with others. Therefore, as the level of potassium supply increases, the supply of potassium becomes a limiting factor for the increase in tuber potassium content.

In order to investigate the effects of different water and nitrogen treatments on potato tuber yield, quality and soil nitrate nitrogen transport in drip irrigation under plastic mulch, a two-factor and three-level complete randomized block design was adopted. Three irrigation treatments(450, 900, 1 350 m³/ha) and three nitrogen treatments(150, 225, 300 kg/ha) were set up respectively, and nine combinations of water and nitrogen were obtained. The yield, commodity, vitamin C, starch, soluble protein, soluble sugar and nitrate content of potato at harvest time, and the nitrate content at different growth stages and in soil layers were measured. The results showed that the yield and commodity rate of potatoes showed a parabolic trend with the increase of nitrogen application and irrigation amount, and reached the maximum of 35 299.9 kg/ha and 77.9%, respectively, at 225 kg/ha N and 900 m³/ha water. Under the same irrigation amount, with the increase of nitrogen application amount, Vc, nitrate content and tuber nitrogen uptake increased significantly. Under the same nitrogen application amount, nitrate content and partial productivity of nitrogen fertilizer decreased significantly with the increase of irrigation amount. At the same time, soluble protein, tuber nitrogen uptake and nitrogen harvest index showed a parabolic trend, and there were significant differences among irrigation treatments. Nitrate nitrogen content in surface soil (0-20 cm) was the highest at all growth stages, and decreased in the 0-100 cm profile. The seedling stage and tuber formation stage of potatoes were the main periods for NO^-₃-N migration to the lower soil layer. Therefore, the nitrogen application rate for potato planting in drip irrigation with film mulching under facilities should be controlled at 225 kg/ha, 900 m³/ha.

In order to explore the effects of irrigation treatments at different growth stages on the growth dynamics, water consumption characteristics, quality, yield and water use efficiency of potato in Hexi Oasis, a field experiment was carried out, taking Qingshu 168 as the material and setting up two irrigation treatments:mild and moderate water deficits. The plant height, leaf area, yield and tuber organic matter content of potato were determined. The results showed that the yield of potato treated with mild water deficit in tuber forming period did not decrease significantly compared with CK, while the water use efficiency, commercial potato rate and bunched potato proportion increased by 22.07%, 10.09 percentage point and 8.20 percentage point respectively, and the dry matter, starch, protein and reducing sugar of potato tubers did not significantly reduced.The mild (WD5) and moderate (WD6) water deficits at tuber bulking stage reduced the potato yield by 15.77% and 18.93% respectively, reaching to a 0.05 significant level, and they were not beneficial to organic matter accumulation of potato tubers and decreased the contents of dry matter, protein and reducing sugar in potato tubers by 1.62 percentage point and 3.38 percentage point, 28.50% and 24.35%, and 34.38% and 46.88%, respectively. The mild (WD7) and moderate (WD8) water deficits at starch accumulation stage had less effect on yield, however, WD7 treatment increased the commercial tuber rate, protein content and reducing sugar content by 8.61 percentage point, 3.11% and 15.63% respectively, while the water use efficiency was not improved significantly. Therefore, in pursuit of higher yield and water use efficiency of potato, mild water deficit treatment at tuber formation stage is the best irrigation strategy in this experiment, but for seeking higher quality of potato, mild water treatment in starch accumulation period is the best.

To study the role and function of potato StNF-Y gene under abiotic stress, a new NF-YC transcription factor(StNF-Y) was cloned from potato resistant to bacterial wilt genotype ED13. Bioinformatics analysis and biological function prediction showed that the full-length cDNA of StNF-Y was 1 132 bp, with an open reading frame of 693 bp, encoding 230 amino acids, with a formula of C₁₁₁₂H₁₇₃₅N₃₁₇O₃₃₉S₁₀ and isoelectric point of 5.37. It contained 13 phosphorylation sites, and StNF-Y protein was distributed in the cytoplasm, without signal peptide.It was a hydrophilic protein. StNF-Y protein contained a highly conserved domain, existed in the BUR6 superfamily. Secondary structure showed that the protein consisted mainly of 45.65% α-helix, 5.65% extended chain, 45.22% random coil and 3.48% β-turn. Phylogenetic analysis showed that the StNF-Y sequence of potato was closely related to the NF-YC sequences of tomato, pepper and tobacco. In addition, StNF-Y played a certain role in a variety of plant stresses, so it was speculated that StNF-Y might be involved in the regulation of potato-related stress resistance. The results would provide a theoretical basis for further research on the function of potato StNF-Y and its resistance mechanism to stress.

In order to explore the correlation between pathogenesis related protein (PR protein) and potato disease resistance, the ability to resist soft rot, bacterial wilt and dry rot in potato was tested. In the previous potato disease resistance study, 17 family gene-binding transcriptome data of PRs were analyzed and the genes were screened, and PR1 was finally determined. The potato Atlantic variety was selected as the material, which was provided by Heilongjiang Academy of Agricultural Sciences. The StPR1 gene was cloned and analyzed by bioinformatics. F.sambucinum and F.avenaceum were used. And E.carotovora subsp. Carotovora Borgey (Ecc), E.chrysanthemi Burkholder. Atroseptica Dye (Ech), can cause soft rot and bacterial wilt. The specific analysis of StPR1 gene expression was carried out after inoculation of potato tuber with E. carotovora subsp. Mc Fadden et Dimock (Eca) and Ralstonia solanacearum (RS). The results showed that the StPR1 gene was 540 bp in length and encoded 179 amino acids. The hydrophobicity and hydrophilicity of the protein are predicted.The GRAV value of the PR1 protein sequence was between +4 and-3, containing hydrophilic and hydrophobic regions, and protein secondary structure. It is predicted to be a mixed protein. The tertiary structure of the protein is predicted to be a tightly complex helical structure with a SCP_PR-1_like conserved domain, which is highly similar to the pepper PR1 gene on an evolutionary branch. The results of qRT-PCR showed that the expression level of StPR1 gene was higher than that of bacterial stress in antifungal stress, and its ability to resist dry rot was better than that against soft rot and bacterial wilt. In summary, when the potato is attacked by external pathogens, StPR1 plays an important role in the disease resistance of the potato.In summary, when the potato is attacked by external pathogens, StPR1 plays an important role in the disease resistance of the potato.

The differences in nitrogen(N) uptake and utilization of different potato varieties at seedling stage in Northeast China were evaluated,and potato genotypes with high responsiveness to N were screened to provide a theoretical basis for the selection and mechanism study of potato N efficient genotypes. Pot experiment was used to compare the differences in the ability of different genotypes of potato to obtain N at the seedling stage under the three levels of N supply and their causes. The results showed that different N supply levels had significant differences in the ability of different genotypes to auumulate N. With the increased of N supply levels,the N accumulation of four potato varieties such as Dongnong 310,Yanshu 4,Kexin 13 and Kexin 22 increased significantly. The response rate was high,while the N accumulation of seven potato varieties such as Dongnong 308,Dongnong 311,Dongnong 312,Dongnong 316,Yanshu 9,Yanshu 7 and Kexin 19 had no significant increase,and the response to N was low. For the genotypes with high nitrogen responsiveness,the Nitrate reductase active(NRA),Glutamine synthetase active(GSA),and root activity a little bit increased significantly with increasing N supply levels,while the chlorophyll(SPAD)values increased less. The increase in N accumulation,NRA,GSA,root activity,and SPAD values were significantly greater than those with low N response. The correlations between N accumulation and NRA,GSA,SPAD,and root activity of potato under low N and high N conditions were analyzed. NRA and GSA activity could better reflect the N accumulation ability of potato during seedling stage,the ratio of SPAD and root activity. The reliability is better,and the strength of NRA and GSA activity can be used as an important indicator for evaluating the N uptake accumulation of potato seedlings.

In order to find out the effect of different potassium doses on the yield and nutrient utilization of purple sweet potato,it provides theoretical and practical basis for the rational application of potash fertilizer. Using design of randomized block experiment,field experiment and chemical analysis method,the different amount of potassium application on low fertility soil accumulation of dry matter,yield and its components purple sweet potato factor,NPK factor accumulation,the effects of potassium use efficiency were studied. The results showed that dry matter accumulation in roots of purple sweet potato was higher than that of K₀ treatment during the growth of sweet potato,when the amount of potassium was 180 kg/ha,the accumulation of root dry matter reached the maximum. Potassium had effect on the accumulation and distribution of dry matter,increased the number of potatoes and single potato weight,and could increase the yield of sweet potato and obtain the largest yield increase when the rate of potassium application was 180 kg/ha. Compared with the K₀,the yield increased by 20.78% and 26.19%,respectively,in 2016 and 2017,and the difference was significant(P <0.05).Compared with K₀ treatment,potassium could promote the absorption of nitrogen and phosphorus in purple sweet potato,significantly increased the accumulation of whole plant nitrogen and phosphorus,and increased the maximum growth rate of K₃. The accumulation amount of the root and the whole plant nitrogen increased by 75.38% and 65.75% respectively,and the cumulative phosphorus accumulation increased by 45.24% and 60.28%,respectively,and difference was significant(P <0.05). Besides,potassium fertilizer treatments could also increase the utilization ratio of potash fertilizer and agronomic efficiency. Compared with K₀,apparent utilization and agriculture utilization increased by 47.82 percentage points and 158.11%,respectively,and the difference was significant(P <0.05). Therefore,the optimum application dosage of potassium fertilizer was confirmed to be 180 kg/ha.

In order to determine suitable planting method and density for fresh edible sweet potato planting in barren hilly in the central region of Shandong Province, L9 and J26 were used as test varieties under field conditions. Each variety was planted vertically and horizontally, with planting densities of 37 500 (D1), 52 500 (D2), and 67 500 plants/ha (D3). We studied the effects of different planting methods and densities on the dry matter accumulation, distribution, yield, and quality of fresh sweet potatoes. An increase in density increased the dry matter accumulation in the middle and late growth stages of the two varieties and significantly decreased the ratio of the dry matter distribution of the branch leaves of J26 planted vertically and horizontally. D2 treatment decreased the ratio of the dry matter distribution of the branch stems of L9 planted vertically and horizontally in the late growth stage and significantly increased the ratio of the dry matter distribution of the tuber roots of the two varieties planted vertically and horizontally in the middle growth stage. The D2 and D3 treatments significantly increased the ratio of the dry matter distribution of the tuberous roots of J26 planted vertically and horizontally in the late growth stage. For the two cultivars at the same transplanting method, D2 and D3 treatments significantly improved the soluble sugar content and starch content in tuberous roots and D2 treatment significantly increased the tuberous root yield of the two cultivars. Compared with vertical planting, horizontal planting significantly increased the dry matter accumulation in the early growth stage under D2 treatment and in late growth stage of J26 under D2 and D3 treatments and in the middle growth stage of L9 at the same density. Compared with vertical planting, horizontal planting increased the soluble sugar content of the tuberous roots of J26 under D1 treatment and that of L9 with different densities. Horizontal planting was also benificial for increasing tuberous root weight per plant and tuberous root yield of the two cultivars. With regard to yield and quality, horizontal planting + D2 treatment is the optimal combination under the test conditions.

In order to study response of the potassium concentration on the expression of KUP6 and KUP7 potassium transporter gene,hydroponic potato seedlings was conducted.The RNA of potato was isolated and checked, the first chain of the cDNA was synthesized by the Reverse Transcriptional Kit, and gene transcription on seedlings was detected by Real-time fluorescence quantitative PCR technique and the content of potassium in potato seedlings was detected.The content of potassium in potato seedlings was detected at 10, 20 and 30 days after potato seedling planting. The results showed that when potassium concentration was 1.00 mmol/L,the expression level of KUP6 and KUP7 was the highest. When potassium concentration was lower than 0.10 mmol/L,the expression was low,and the expression level of potassium decreased when potassium concentration was 10 mmol/L. It indicates that higher and lower potassium concentration is not conducive to the expression of KUP6 and KUP7 genes. Potassium content in roots, stems and leaves showed that potassium concentration reached its absorption saturation at 1.00 mmol/L for root. The higher potassium concentration in hydroponics, the higher potassium content in root, stem and leaf. The difference of potassium content in stem and leaf was decreased when lower potassium concentration in hydroponics and increased when higher concentration.