Study On The Genetic Diversity Of Perennial Wild Soybean G.tomentella And G.tabacina In China

The genus Glycine Willd.has two subgenera,the subgenus Soja,which contains two annual species,G.max[L.]Merr.and G.soja Seib.&Zucc.and the subgenus Glycine containing 26 perennial wild species;now,there are only two perennial wild soybeans,Glycine tabacina and Glycine tomentella,to be identified according to Flora of China in China.Perennial wild soybeans,as a wild relative of cultivated soybean,have high utilization value for providing excellent agronomytraits and resistance of gene source,broadening genetic basis,and making innovative germplasm resources for soybean breeding.At present,there are few studies on G.tabacina and G.tomentella in our country,so there is a lack of understanding of the geographic distribution,biological characteristics,genetic diversity,population structure,and geographical genetic differentiation of the two species,but given that the perennial wild soybeans have more excellent agronomic and resistance traits with potential application value for the future breeding of soybean.It is urgent to start and clarify the basic genetic information on population genetic diversity and population structure of G.tabacina and G.tomentella for providing a theoretical basis for the effective protection of subgenus Glycine genetic resources in China.In this study,genetic diversity of 708 G.tabacina individuals from 28 populations and 291 G.tomentella individuals from 11 populations on the southeastern coastal islands of China were analyzed using 22 pairs and 25 pairs of SSR genetic markers respectively.The results were as follows:Glycine tabacina1.G.tabacina had abundant genetic variation.By using 22 pairs of SSR genetic markers,a total of127 alleles were detected.The average number of alleles per locus was 5.8 and the number of effective alleles was 2.385.The mean of heterozygosity and observed heterozygosity were 0.505 and 0.035,respectively,and the average PIC was 0.456.2.G.tabacina had a relatively high outcrossing rate estimated by mean outcrossing rate of single locus(t_s=6.52%)and multilocus(t_m=6.75%);AMOVA results showed that 43.55%of the genetic variation existed among populations,49.66%of genetic variation existed within the population,and the average genetic differentiation index(Gst)was 0.436;spatial autocorrelation results showed a positive and significant genetic correlation within a radius of approximately 14.70 km to one another;individual assignment test and haplotype analysis revealed a long-distance dispersal events(>200 km dispersal was inferred,but>56 km dispersal was observed).3.The results of NJ clustering on population level and Structure were highly consistent showing that G.tabacina had a certain geographic differentiation and was clustered into three major groups,North,Middle north,and regions except the North;among them,the North and Middle north had higher genetic diversity and were inferred to be the genetic diversity center of G.tabacina in China.Glycine tomentella4.G.tomentella also had abundant genetic variation.After detection of 25 pairs of SSR primers,a total of 179 alleles were detected.The average number of alleles per locus was 7.2,and the number of effective alleles was 3.494.The expected heterozygosity and observed heterozygosity were 0.595 and0.035,respectively,and the average PIC was 0.562.5.G.tomentella also had a relatively high outcross rate(t_s=8.23%,t_m=5.74%);AMOVA results showed that the genetic variation among populations(60.96%)was greater than that within population(33.47%)presenting a characteristic of self-pollination plant;the average genetic differentiation index(Gst)was 0.61;Spatial autocorrelation results showed that there was a positive and significant genetic correlation within 30.45 km.6.The NJ clustering and Structure analysis based on individual levels showed that G.tomentella had three genetic structure and a conservative geographical distribution.100%of individuals were clustered to the island where the population was located,and there was no exchange of inter-island material.Clustering on population levels showed that populations distributed on the same island were grouped together.Haplotype analysis revealed that only one individual migrated,which happened between two populations on the same island.