Association Analysis Of Genotyping Data Uncovered Strong Relationshiop Between Draught, Salt Tolerance Identification In Collected Soybean (Glycine Max) Cultivars And Selected SSR Markers

Abstract: Soybean is one of the most important cash crops, which is rich in protein, fat and many kinds of bio-active substances, such as soybean isoflavones, saponin, Vitamin E and so on. However, the yield of soybean in China remains low even today, The productivity and quality of soybean industry are significantly hampered by drought and salt stress every year. It is important to improve the drought and salt tolerance of soybean to insure the high and stable yields.In this study we collected ninety one soybean varieties from Huanghuai and Northeast regions of China, which had been bred early from 1940 and were cultivated in large scale today. Then selected plants were grown in artificial climatic chamber to evaluate duplicate phenotypes of drought and salt tolerance in natural population. Then, genotyping of selected materials were carried out with sixty eight simple-sequence repeat markers. Linkage disequilibrium of pairwise loci and population structure were analyzed along with association analysis between SSR loci and tolerance to stress. The elite alleles of the tolerance to stresses traits along with their carriers were detected at last. The main results were as follows.1. Identification of drought toleranceDuring the drought tolerance identification in the whole growth period we found that there were many differences between the treatment and the control, e.g. plant height, pod height, sessions, grains and grain weight per plant decreased in some extent, the decline were 2%, 7%, 8.5%, 6% and 27%, of which the biggest drop is grain weight per plant. These results indicated that the impact of drought on the yield was the biggest. Principal component analysis determined these five indicators for association analysis. Then we classified the varieties after drought tolerance identification in budding stage, the relative germination rate of the first class was better than that of five classes. KaiYu 10 was excellent in these experiments.2. Identification of the salt toleranceDuring the salt tolerance identification before flowering stage we found that salt damage by treatment significantly inhibited the growing of plants compared with the control. Some even died in the treatment. After classification the salt tolerance we found that the varieties from Northeast were better than that from Huanghuai.3. Association analysisThe different degrees of LD were detected not only among syntenic markers but also among nonsyntenic ones, suggesting that there had been historical recombination among linkage groups. Genetic structure analysis showed that the population was composed of two subpopulations, which associated with its geographic eco-types, indicating the classification of geographic eco-types was of sound genetic bases. Sixteen SSR loci associated with the traits were screened out from the population. Two loci associated with salt tolerance trait were in the same linkage group. The elite alleles of the tolerance to stresses traits along with their carriers were detected, such as the allele Satt045-A124 for salt tolerance (1 class for Fengshou19) and so on.