Association Analysis Of Soybean Seedling-related Traits Under Drought Stress

Soybean plays an important role in world agricultural production because of its high economic value and nutritional value.Screening drought-tolerant varieties and discovering drought-tolerant genes is the most economical and effective method.In this study,9 traits related to drought tolerance of soybean seedlings were selected,and 300 soybean seedlings were phenotyped.The drought tolerance of 300 soybean seedlings was comprehensively evaluated.210 SSR markers were used to conduct association analysis on drought tolerance-related traits of soybean seedlings,and gene annotation was performed on the associated loci to screen the associated loci and their excellent allelic variations and corresponding vector materials for drought tolerance traits in soybean seedlings.The main results are as follow:Diversity analysis of drought tolerance-related traits in seedlings of 300 soybean varieties was carried out.The coefficient of variation was between 14.29% and 52.54%,and the phenotypes of drought tolerance traits were widely varied.The degree of correlation among the 9 drought tolerance-related traits was high.According to the first four PCA extracted from the principal component analysis,the membership function values were calculated,and two extreme drought-tolerant varieties,Suinong 36 and Beidou 10,were obtained,which could provide resource information and parental materials for cultivating drought-tolerant soybeans.A total of 1498 alleles were amplified from the results of genetic diversity analysis,and the amplified genes for each marker were at most 22 and at least 2.The average number of allelic variation on each chromosome increased with the average polymorphic information content(PIC value),and 210 pairs of SSR markers were polymorphic.The two models of TASSEL software co-located 20 SSR loci associated with seedling stage and drought tolerance traits,which were distributed on 12 chromosomes.Co-localized to 20 SSR loci associated with drought tolerance traits in soybean seedling stage,distributed on 12 chromosomes,Satt201 and Satt441 were significantly associated with relative germination rate;Satt531,Satt186,Satt577 and Satt347 were significantly associated with relative germination potential;Satt441 was significantly associated with relative hypocotyl length;Satt311 was significantly associated with relative seedling height;Satt211,Sat?256 and Satt492 were significantly associated with relative leaf fresh weight;Satt588,Aw277661,Satt373,Satt477 and Satt387 were significantly associated with relative cotyledon fresh weight;Satt347 was significantly associated with relative axis fresh weight;Satt142,Satt481,Satt492,Satt211,Satt197 and Sat?337 were significantly associated with relative root fresh weight;Satt492,Satt211 and Sat?119 were significantly associated with relative shoot fresh weight.The same SSR locus was often associated with multiple drought tolerance-related traits.Among the 300 soybean materials,a total of 78 excellent allelic variants with synergistic effects were discovered,which played an obvious synergistic effect on the drought tolerance traits of soybean seedlings.The maximum allelic variation of the 9soybean seedling stage drought tolerance traits studied in this paper and the corresponding vector materials carrying the excellent allelic variation are Satt201?146bp(Hefeng48),Satt531-238bp(Heinong51),Satt441-281bp(Heinong66),Satt311-249bp(Suinong36),Satt211-387bp(Tonghuabaimei),Aw277661-257bp(Hejiao11),Satt347-260bp(Kendou41),Satt142-197bp(Huangjinta),Sat?119-193bp(Niumaohuang).