Discovery of SNPs in important legumes through comparative genome analysis and conversion of SNPs into PCR-based markers

Abstract

Compared to cereal crops several legumes are less characterized at the genomic level and rightly referred as orphan crops. Transfer of knowledge between model and crop legumes allows development of orthologous pan-taxon genomic tools to benefit research on resource poor taxa. Here, we developed 278 intron flanking gene-specific markers by BLAST aligning pigeonpea (Cajanus cajan (L.) Millsp.) expressed sequence tags (ESTs) with complete genome sequence of barrel medic (Medicago truncatula). A random 192 PCR primer pairs representing loci across the haploid genome (n = 8) of barrel medic were tested on a few important members of legume family. The single copy amplification rates of 31.8% (peanut, Arachis hypogaea) to 77.6% (barrel medic) signifies the success of cross taxon primers and suggested their potential use in comparative legume genomics. Genetic diversity was assessed in 48 pigeonpea genotypes using 143 intron flanking markers which revealed 71 polymorphic markers with PIC values ranging from 0.04 to 0.45 with an average of 0.23 per marker. The PCR products of different varieties of pigeonpea, cowpea and chickpea were sequenced and aligned to find putative SNPs. Integration of these newly developed markers into genetic maps in resource poor legumes will not only aid in the map saturation but also in designing successful marker-assisted selection programmes.