Development and application of EST–SSRs markers for analysis of genetic diversity in erect milkvetch ( Astragalus adsurgens Pall.)

Erect milkvetch (Astragalus adsurgens Pall.) is a major legume forage plant widely grown in Northern China. However, the lack of molecular markers has limited its research into its genetic diversity and work on germplasm improvement. In this study, a total of 39,163 EST–SSR loci were identified from 30,262 unigene sequences in the erect milkvetch transcriptome using Illumina sequencing. Moreover, 22,367 EST–SSR primer pairs (PPs) were successfully designed. In addition, 100 PPs were synthesized and preliminarily screened in two accessions; of these, 90 were determined to be clear and stable EST–SSR markers. Fifty-one PPs were randomly selected in order to assess the genetic diversity of 27 erect milkvetch accessions. The average polymorphism information content of the 51 PPs was 0.682. Greater genetic diversity was detected in accessions from Inner Mongolia and in the group of landrace and wild erect milkvetch accessions. This study provides an important resource for germplasm improvement and genetic diversity analysis in erect milkvetch.