Identification of novel loci for flowering time in mungbean [Vigna radiata (L.) R. Wilczek] using genome-wide association study.

BACKGROUND: Flowering time is an important crop trait. Mungbean flowers do not flower simultaneously, leading to asynchronous pod maturity and laborious multiple harvests per individual plant. The genomic and genetic mechanisms of flowering in mungbean are largely unknown. OBJECTIVE: This study sought to discover new quantitative trait loci (QTLs) for days to first flowering in mungbean using a genome-wide association study (GWAS). METHODS: In total, 206 mungbean accessions collected from 20 countries were sequenced using genotyping by sequencing. A GWAS was conducted using 3,596 single nucleotide polymorphisms (SNPs) using TASSEL v5.2. RESULTS: Seven significant SNPs were associated with first flowering time. Based on the linkage disequilibrium (LD) decay distance, LD block was determined from upstream to downstream of each SNP up to 384 kb. The lead SNP (Chr2_51229568) was located in the DFF2-2 locus. Syntenic analysis between mungbean and soybean revealed the DFF2-2 locus had collinearity with soybean genomic regions containing flowering-related QTLs on Gm13 and Gm20. CONCLUSION: Identification of flowering-related QTLs and SNPs is important for developing synchronous pod maturity and desirable flowering traits in mungbean.