Development of SSR markers and assessment of genetic diversity of adzuki bean in the Chinese germplasm collection

Abstract

Adzuki bean is an important food legume crop in East Asia. China is ranked as the number one country for its production and consumption. A large number of adzuki bean accessions are maintained in the Chinese national seed genebank. Tapping its genetic diversity may have potential in assisting breeding programs for new cultivar development and improvement. However, its genetic diversity was not well evaluated due to lack of sufficient DNA markers. For marker development, we initiated de novo transcriptome sequencing of adzuki bean. From sequence assembly, 65,950 unigenes were identified, and some of them were used for EST-SSR (eSSR) marker development. A set of 53 SSR markers were developed from adzuki bean, and 110 SSR (including 57 already available) markers were used for genotyping of 261 selected accessions. These adzuki bean accessions were classified into 10 clusters. The accessions from North China were well separated from the accessions from South China. The average polymorphic information content of genomic SSR (gSSR) markers and eSSR markers was 0.5081 and 0.2382, respectively. Results indicate that gSSR markers were more polymorphic than eSSR markers. These polymorphic eSSR and gSSR markers will be useful for assisting adzuki-bean-breeding programs and future germplasm curation.