Study On The Genetic Diversity In Wild Soybean (G.soja) Growing In Beijing

Wild soybean (Glycine soja) is commonly accepted as the ancestral species of the cultivated soybean (G. max). As valuable genetic resources, wild soybean is an extraordinarily important gene pool for soybean breeding. In recent years, with the development of economy and the enhancement of population, some factors destroyed the survival environment of wild soybean. Now many valuable resources have been disappearing. Therefore, in order to provide scientific basis in making rational collecting, in-situ conservation, academic study and effective use of wild soybean resources, we collected natural populations of wild soybean growing in Beijing and analysed the genetic diversity.Ten natural populations of wild soybean in Beijing were collected. Each population had 30 individuals except population No.2 (28 individuals) and the total samples contained 298 individuals. We planted these individuals in the exprimental field and then investigated 11 morphologic characters including 4 qualitative and 7 quantitative traits. A set of 40 pairs of SSR primers with 2 pairs of primers per linkage group were used to analyse the genetic diversity. The results were as follows:1. The polymorphisms of the qualitative traits were simple; the variations (differences) in the quantitative traits were bigger within the populations and somewhat presented a region-dependent distribution geographically although some traits were different in distribution patterns. The CV of traits were showed as the follows: Leaf lengthxwidth>yield per plant>aboveground biomass>Growth rate >Plant height> 100-seed weight>Days from sowing to flowering. The Shannon-Weaver indexes of the quantitative traits were higher than those of the qualitative traits. The highest Shannon-Weaver index was 1.42 for the Northern mountainous area, while the lowest value of 1.19 for the Eastern mountainous one. The Shannon-Weaver index of population No.1 was the highest, while that of population No.9 was the lowest. Based on the morphological data, the 10 natural populations were clustered into 4 groups.2. In 10 natural populations, 526 alleles (bands) were detected in total. The average number of alleles per locus (A) and the effective number per locus (A_e) were 12.75 and 6.98, respectively. The mean values of expected heterozygosity and Shannon-Weaver index were 0.369 and 0.658, respectively. The natural populations showed a value of 0.446 for between-population genetic diversity (H_s) and 0.362 for within-population genetic diversity (D_ST). The coefficient of gene differentiation for the loci among the populations were estimated to be 0.544. The mean observed heterozygosity (H_o) of mulilocus was 1.29%. This study showed that the centre and western ecotopes had higher genetic diversity than the northern and eastern ecotopes and there were geographic genetic differentiation between the Taihang and the Yanshan mountains in natural populations of wild soybean in Beijing region. A drought-tolerance population presented extremely low genetic diversity, which seemed to have undergone and survived aridity and is expected in exploitation of tolerance gene(s) for crop breeding and applied ecology.