| Drought is the main limiting factor for sustainable development of potato industry in the middle east of Gansu province.Potato plants physiological function disorders and metabolic disturbance were caused by drought,which can lead to the decrease of yield and quality.The common potato cultivation is highly heterozygous autotetraploid,domestic in long-term potato breeding and most of them will use similar genetic background of germplasm resources,resulting in an existing varieties and narrow genetic background,closely related characteristics.Introduction the potato germplasm resource,wild species and the original cultivar,evaluation the drought resistance of introduction resources and reveal the mechanism,these laid a theoretical and practical basis for the effective use of potato germplasm resources.Selecting the different potato germplasm resources from the International Potato Center as the material,controlling irrigation and natural rainfall conditions,evaluate drought resistance by testing yield indexes,to select suitable products for high yield and quality of potato planting in Gansu area of Middle East,Lu Jia Gou Zhen Dingxi city in typical arid area under natural rainfall,drought resistant germplasm screening in the field.Using PEG-6000 as drought stress to determinate physiological and biochemical characteristics on the basis of drought resistance materials,in order to further research the mechanism of introduction potato germplasm resources,analyze the related enzyme cloning EST-SSR analysis of genetic diversity and proline metabolism.The main results are as follows:1.Using membership function value method,drought resistance coefficient of direct evaluation method and comprehensive D value method.Under the controlling irrigation and natural rainfall conditions of 88 plant materials of potato tuber number per plant,biomass per plant fresh weight,dry weight,root fresh weight,root dry weight and fresh weight per plant and tuber tuber dry weight of drought resistance evaluation,the results showed that: C36,C37,C23,C65 and C7 of the drought resistance coefficient(CDC value)were greater than the average value of 0.97;the comprehensive evaluation of drought resistance(D)values were 6.59,5.52,5.94,5.29 and 5.23,result evaluation and drought resistance coefficient,and the cluster analysis based on the D value in the 7.01 clustered,accounting for 5.68% of the total,which belongs to the high resistance drought material.2.In the field of natural rainfall environment,118 variation coefficient of potato germplasm agronomic traits from big to small in turn order: leaf area > stem number > plant height >stem diameter > emergence rate > vegetation coverage rate > chlorophyll content,and in addition to the number of main stem(p<0.05),other agronomic index and tuber yield of different varieties of potato were significantly differences(p<0.01).Correlation analysis showed that the correlation of potato yield and its germination rate,vegetation cover index,plant high and stem diameter as well as number of main stem were significantly positive correlation(p<0.05),and between each index and yield exist obvious linear relationship,the suitable regression equation with y = ax ± b.Through principal component analysis,extract six principal components,yield,vegetation coverage rate,emergence rate,plant height,stem diameter and number of main stem.By cluster analysis,the results can be tested materials are classified into four categories in the similar coefficient of about 6,the four classes of 17 materials yield were higher,average yield 30341.9 kg·hm-2,and other indicators in all of the introduction of potato germplasm resources in the optimal.3.EST-SSR molecular marker technique was used to analyze the genetic diversity of the introduced potato germplasm resources.Selecting 21 pairs primers of high polymorphism and clear bands.PCR amplification of the tested materials was carried out.The results showed that 923 alleles were detected,684 polymorphic were detected,and the polymorphism rate was 68.55%.The length of the amplified DNA fragment was more concentrated in 100-600 bp.On average,each pair of primers amplified 44 alleles,mostly in 35-54,in which the STM13 polymorphism bands were 59,and the SSR pattern was the most obvious.Therefore,the primer STM13 could be used as the molecular basis for the identification of 63 potato germplasm resources.Clustering analysis of the genetic similarity coefficient of 0.715,63 tested potato materials were divided into four groups,the class I includes 47 varieties,accounted for the tested potato materials 74.60%.At the genetic similarity coefficient is 0.733 and can be divided into two subgroups,namely A1 and A2,A1 subtypes categories including 24 of potato germplasm resources,in which the C55,CA57 and C58 clustering together and close relationship.The three germplasm resources were adapted from the Chinese Academy of Agricultural Sciences of vegetables and flowers,belonging to the Solanum demissum different lines.A2 subtypes including 13 germplasm resources,The type II,includes five germplasm resources,C40,C59,C60,and C61 and C63,which three germplasm resources C59,and C61 and C63 as Solanum phureja.It is a diploid potato germplasm resource,poly as a class.The type III,including three germplasm resources,C16,C17 and C20,were cited from International Potato Center.The type IV includes eight germplasm resources,compared with other germplasm resources,genetic relationship is far.EST-SSR marker is helpful to the utilization of potato genetic resources,and it can play a guiding role in the selection of parents of hybrid breeding of potato.4.Based on field screening,selection of different field drought resistance of 12 introduced potato germplasm resources.The superoxide(SOD),peroxidase(POD)and catalase(CAT)activity,proline(Pro)and malondialdehyde(MDA)content were measured after PEG-6000 treatment.Results show that,15% PEG,the SOD activity of introduction potato germplasm resources C36,C37,C23,C66,C51,C29 and C2 reached the maximum value.Comparing with 0% PEG6000(CK)treatments,it increased by 41.40%~ 88.44% respectively.The POD activity of C23,C2 and C12 were increased by 31.91%,52.10% and 43.22% than CK.CAT enzyme activity of C37,C23,C51,C2 and C30 were increased by 12.92%~44.35%compared with CK treatment.The proline content of C23,C36 and C37 were increased by 21.76%,35.41% and 15.00% than CK.MDA content of C37,C23,C51,C29,C2,C30 and C72 reached the maximum value and increased by 15.95%~65.20% compared with CK.In the concentration range of 10% to 20% PEG,the content of MDA and the activity of enzyme with PEG concentration increased significantly,and it decreased when PEG concentration reached 30%,the potato seedlings severe dehydration,the cell membrane penetration damage and lead to a decrease in enzyme activity and drought resistance of different varieties to maintain enzyme activity of different.PEG-6000 simulated drought stress in the introduction potato germplasm resources of the 12 materials,C36 and C37 drought resistance is better.5.RNA of introduced potato germplasm resources "C37" leaves was used as the test material,cloning the related genes of proline metabolism,which were StP5CS1,StP5CS2,StP5 CR and StProDH.The full-length of StP5CS1 gene cDNA sequence is 2649 bp,containing a 2154 bp open reading frame(ORF),encoding a protein of 717 amino acids,and its molecular weight is 77473.5 kDa,isoelectric point(p I)is 5.64.The full-length of StP5CS2 cDNA sequence is 1899 bp,all open reading frame.Encoding a protein of 632 amino acids,and its molecular weight is 68446.6 kDa,isoelectric point(pI)is 5.76.The full-length of StP5 CR cDNA sequence is 1417 bp,825 bp open reading frame encoding a 274 amino acid protein,its molecular weight is 28311.6 kDa,isoelectric point(p I)was 8.59.the full-length of StProDH cDNA sequence is 2113 bp,1503 bp open reading frame encoding a 500 amino acid protein,its molecular weight is 56293.7 kDa,isoelectric point(pI)6.23.Comparison of the amino acid sequence analysis and phylogenetic tree construction,the cloned gene and has been reported in other plant proline metabolism related genes with high homology of amino acid sequence. |
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