Genetic Diversity Analysis And Drought Resistance Evaluation Of Potato(Solanum Tuberosum L.)plantlets

Potato(Solanum tuberosum L.) is the fourth largest food and feeding crops in the world. It’s very sensitive to water deficit, which may cause severe impact on their growth and development. Therefore, the genetic diversity study of potato germplasm resources has a positive sense on their preservation, collecting and innovation. Understanding the drought resistant mechanism of potato germplasm, evaluation and identification their drought resistance laid a theoretical foundation to select and breed new potato germplasm.Firstly, the genetic diversity and population structure of 135 introduction potato germplasm was analyzed; Secondly, plantlets transplanting water stress experiment(PEG6000 treatment and without water treatment) was conducted using 44 potato materials randomly selected among of them. And then, 12 materials and 2 materials with enzyme activity ranges larger and lower, respectively, were chosen as materials of gradient stress test with PEG6000 concentration 0%, 3%, 6% and 9%, respectively. The main results were as follows:1. A total of 23 SSR markers on 12 chromosomes of potato material were used to analysis the genetic diversity of 135 introduction potato germplasm, 67 polymorphic bands were detected. Each marker could detect 2-5 loci with 2.9130 loci in average. The range of Shannon-wiener index was 0.2641 to 1.3484 with a mean of 0.7848 and the range of polymorphism information content(PIC) was 0.1372 to 0.7320 with a mean of 0.4679, showing that the detection efficiency of chosen SSR markers was higher, the genetic variation between tested potato materials were larger and the genetic diversity was abundant. By related software clustering analysis showed that the genetic similarity coefficient(GS) changed in the range of 0.4849 to 0.9697 and 135 potato materials can be divided into six types at the level of 0.670. Population structure analysis found that 135 materials can be divided into five subgroups, each subgroup contains 23, 25, 26, 33, 28 potato materials, respectively. And the result of cluster analysis and structure analysis results are inconsistent, showing that a great genetic difference exist between tested potato genotypes.2. Studies on potato transplanting plantlets treated by 10% PEG6000 and without water process found that under two different water stress, the activity of POD, CAT and the content of soluble protein in potato plants relatively increased compared with control, and two stress modes has higher consistency in the study of crop drought resistance, so PEG6000 can better simulate water stress, and can be used in the study of potato drought resistance.3. The growth and physiological and biochemical of all potato plantlets in vitro affected gradually serious with the increase of PEG6000 stress concentration. Under 9% PEG6000 stress, 14 varieties showed the largest differences and five growth indicators such as plant height, root length and so on, and were significantly lower than that in control. Therefore, 9% PEG6000 was optimal concentration to simulate water stress for potato tuber seedlings. Under such stress concentration, the average of relative root length for tested materials was 7.99%, decreased most and had the largest variation coefficient of 82.13%, which illustrated that the relative root length was the most sensitive to water stress among all indicators.4. For evaluation the drought resistance of the potato germplasm materials comprehensively, avoided the bias caused by single index determination, we analyzed the growth and physiological indexes of 14 tested potato material comprehensively by the method of principal component and subordinate function. According to the size of comprehensive evaluation value D, the order of drought resistant from high to low was as follows: L3、38(CIP 391930.1)、2(CIP 397098.12)、39(CIP 391931.1)、35(CIP 304405.47)、19(CIP 392759.1)、23(CIP 397035.26)、20(CIP 393613.2)、25(CIP 302476.108)、27(CIP 304345.102)、13(CIP 391180.6)、DXY、15(CIP 391724.1)、18(CIP 392745.7).