A candidate flowering gene in mungbean is homologous to a soybean Phytochrome A gene

Abstract

Flowering in mungbean is irregular, resulting in asynchronous pod maturity that necessitates multiple harvests per crop and increases time and labor costs. Control of flowering time is essential for increasing mungbean yield; however, few studies to date have examined quantitative trait loci (QTL) associated with flowering time in mungbean. Here, a genetic map was constructed by genotyping-by-sequencing in an F6 population of 190 recombinant inbred lines (RILs) derived from a cross between VC1973A and V2984. In total, 1321 SNP markers were incorporated into 11 linkage groups. Days-to-first-flowering (DFF) and days-to-flowering (DF) were determined, and QTL analysis was performed. A QTL for both DFF and DF was detected on chromosome 3 (Chr3) with LOD scores of 15.8 and 18.7, respectively. Flowering-related QTLs and genes are well-studied in soybean. Syntenic analysis between mungbean and soybean revealed synteny of the mungbean Chr3 region with a soybean region containing QTLs for first flower that mapped to key flowering genes encoding phytochrome A (PHYA). A candidate flowering gene, Vradi03g07170 (VrPHYA), homologous to soybean PHYA, was identified in the Chr3 syntenic block. In summary, mungbean flowering QTLs were identified on a high-density genetic map and a candidate flowering gene was discovered that will be highly helpful for controlling flowering time in a mungbean breeding program.