| There were 1300 soybean released cultivars (SRC) in China between 1923 and 2005, this was most importance core germplasm, the marked purport of the present study was to reveal the genetic diversity, population specificity and genetic relation of SRC in China, and the practical guidance to broaden improving on present SRC. This study selected 378 SRC to be composed of representative sample, and to select reference 110 soybean cultivars from Korean Peninsula, Southern Asia and South Asia. A total of 64 simple sequence repeat (SSR) markers scattered on the genome were used to analyze the genetic diversity of SRC sampled in China and Asia introduction cultivars (AIC), and the study to reveal the population specificity and complementary in each population of China, and AIC on the application to broad genetic base of SRC in China. The genotyping data of 85 SSR markers (based on 64 SSR markers increased 21 SSR to be relation with agronomic trait) on 190 representative released cultivar population (RCP) (190 cultivars was the component part of 378 SRC in China) were obtained and analyzed for LD of pairwise loci and population structure, and then for association between SSR loci and 11 soybean agronomic traits of two-year-experimentation in the field under TASSEL GLM (General linear model) program, and the study on trace of elite alleles (EA) of yield and quality traits in the pedigree of major cultivar families released in Huanghuai Valleys and Southern China. The main results were obtained as follows.There were 572 alleles of genetic richness,8.94 alleles per locus,0.752 of PIC in RCP of China. There were 16.3 (0.74) and 17.6 (0.86) of alleles per locus (Simpson index) respectively in landrace and wild population of China, using basic same marker by study of Wen Zixiang in 2008. There existed to tend narrow genetic base of RCP in China, to broad its genetic base for soybean future last breeding.Based on genetic richness and genetic diversity indexes as well as specifically existent, specifically deficient and complementary alleles, there existed a plenty of genetic diversity in RCP of China as well as a plenty of complementary alleles among provincial subpopulations (Heilongjiang, Jilin, Liaoning, Henan, Shandong, Anhui, Beijing and Jiangsu), especially most between Liaoning and Henan subpopulation. Along with the period advance, some of the old alleles in earlier subpopulation disappeared and some new alleles came out in later subpopulation with the new ones mostly more than the old ones. Specifically existent and specifically deficient alleles in each subpopulation were detected. Significant relationship was found between SSR clusters and provincial subpopulations as well as period subpopulations, indicating the sound genetic bases of the classification of provincial subpopulations as well as period subpopulations. There existed plenty of complementary alleles between pairs of populations for broadening the genetic bases of the respective geographic cultivar populations, along with there markedly existed genetic different from each period subpopulation for cultivating new breed to store material in earlier SRC.There were 585 alleles of genetic richness,9.14 alleles per locus,0.733 of PIC in RCP of Asia. According to the model-based clustering method for using multilocus data to infer population structure and assign cultivars to populations (structure analysis), two ancestry sources in Asia were detected, one composing the most part of Chinese cultivar group, another composing the most part of exotic cultivar group. The composition of the two ancestry sources in the geographic populations was different markedly. The soybean of foreign was spread from China, there was differentiation in soybean between China and foreign, because of each country specific condition of geographic and manual work selection.There existed a plenty of alleles and genetic diversity of RCP in Asia as well as a plenty of complementary alleles among geographic populations (Northeast China, Huanghuai China, Southern China, Korean Peninsula, Southeast Asia and South Asia), especially most between Huanghuai China population and South Asia population. Specifically existent and specifically deficient alleles in each geographic population were detected. Significant differentiation among geographic populations was found, while the least differentiation between the Chinese group and exotic group was in the pair of Southern China population vs. Southeast Asia population, that within exotic group was in the pair of Southeast Asia population vs. Korean Peninsula population, and that within Chinese group was in the pair of Huanghuai China population and Southern China population. There existed plenty of specifically existent and deficient loci and alleles in each geographic population, and therefore, plenty of complementary alleles between pairs of populations for broadening the genetic bases of RCP in China by AIC.LD was detected extensively not only among syntenic markers but also among nonsyntenic ones in RCP, while the loci pairs with D’>0.5 accounted for only 1.71% of the total ones. The syntenic D value attenuated fastly along with the increase of genetic distance. Genetic structure analysis showed that RCP was composed of seven subpopulations. The 45 SSR loci with a total of 136 loci (time) was found to be associated with 11 agronomic traits in the RCP. Among those,22 loci (time) were consistent with mapped QTLs from family-based linkage mapping procedure and 43 loci (time) were consistently detected in two experiment years. There were only a few same association loci and most different loci among SRC and landrace, wild population of China, with landrace and wild population of China using most same marker by study of Wen Zixiang in 2008. There was 3.3% or 3.4% same association loci ratio total loci about 100-seed, plant height, etc.6 traits between SRC and landrace or wild of population. There existed to be found markedly different genetic structure among SRC and landrace or wild population.The yield EA were emphasis on analysis in mainly family (58-161, Xudou 1, Qihuang 1, Nannong 493-1 and Nannong 1138-2) of SRC Huanghuai Valleys and Southern in China, there were EA each other in pedigree ancestor, based on pedigree ancestor new cultivar cumulative more EA in course of derivation. EA of pedigree ancestor were more lost in new cultivars along with breeding cycle change. There was markedly different EA structure between high yield and low yield cultivars, and there was different EA structure in each high yield cultivar.5 families’ cultivars were furthered improve yield potential. |
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