Determination of the genetic diversity of vegetable soybean [Glycine max(L.) Merr.] using EST-SSR markers

The development of expressed sequence tag-derived simple sequence repeats(EST-SSRs) provided a useful tool for investigating plant genetic diversity.In the present study,22 polymorphic EST-SSRs from grain soybean were identified and used to assess the genetic diversity in 48 vegetable soybean accessions.Among the 22 EST-SSR loci,tri-nucleotides were the most abundant repeats,accounting for 50.00% of the total motifs.GAA was the most common motif among tri-nucleotide repeats,with a frequency of 18.18%.Polymorphic analysis identified a total of 71 alleles,with an average of 3.23 per locus.The polymorphism information content(PIC) values ranged from 0.144 to 0.630,with a mean of 0.386.Observed heterozygosity(H o) values varied from 0.0196 to 1.0000,with an average of 0.6092,while the expected heterozygosity(H e) values ranged from 0.1502 to 0.6840,with a mean value of 0.4616.Principal coordinate analysis and phylogenetic tree analysis indicated that the accessions could be assigned to different groups based to a large extent on their geographic distribution,and most accessions from China were clustered into the same groups.These results suggest that Chinese vegetable soybean accessions have a narrow genetic base.The results of this study indicate that EST-SSRs from grain soybean have high transferability to vegetable soybean,and that these new markers would be helpful in taxonomy,molecular breeding,and comparative mapping studies of vegetable soybean in the future.

Developing new SSR markers from ESTs of pea(Pisum sativum L.)

The development of expressed sequence tags(ESTs) from pea has provided a useful source for mining novel simple sequence repeat(SSR) markers.In the present research,in order to find EST-derived SSR markers,18 552 pea ESTs from the National Center for Biotechnology Information(NCBI) database were downloaded and assembled into 10 086 unigenes.A total of 586 microsatellites in 530 unigenes were identified,indicating that merely 5.25% of sequences contained SSRs.The most abundant SSRs within pea were tri-nucleotide repeat motifs,and among all the tri-nucleotide repeats,the motif GAA was the most abundant type.In total,49 SSRs were used for primer design.EST-SSR loci were subsequently screened on 10 widely adapted varieties in China.Of these,nine loci showed polymorphic profiles that revealed two to three alleles per locus.The polymorphism information content value ranged from 0.18 to 0.58 with an average of 0.41.Furthermore,transferable analysis revealed that some of these loci showed transferability to faba bean.Because of their polymorphism and transferability,these nine novel EST-SSRs will be valuable tools for marker-assisted breeding and comparative mapping of pea in the future.