A deep sequencing analysis of transcriptomes and the development of EST-SSR markers in mungbean (Vigna radiata)

Mungbean (Vigna radiata L. Wilczek) is one of the most important leguminous food crops in Asia. We employed Illumina paired-end sequencing to analyse transcriptomes of three different mungbean genotypes. A total of 38.3-39.8 million pairedend reads with 73 bp lengths were generated. The pooled reads from the three libraries were assembled into 56,471 transcripts. Following a cluster analysis, 43,293 unigenes were obtained with an average length of 739 bp and N50 length of 1176 bp. Of the unigenes, 34,903 (80.6%) had significant similarity to known proteins in the NCBI nonredundant protein database (Nr), while 21,450 (58.4%) had BLAST hits in the Swiss-Prot database (E-value<10⁻⁵). Further, 1245 differential expression genes were detected among three mungbean genotypes. In addition, we identified 3788 expressed sequence tag-simple sequence repeat (EST-SSR) motifs that could be used as potential molecular markers. Among 320 tested loci, 310 (96.5%) yielded amplification products, and 151 (47.0%) exhibited polymorphisms among six mungbean accessions. These transcriptome data and mungbean EST-SSRs could serve as a valuable resource for novel gene discovery and the marker-assisted selective breeding of this species.