Improvement of mungbean reference genome and QTL identification for synchronous pod maturity

Abstract

Mungbean (Vigna radiata (L.) R. Wilczek) is a good source of carbohydrate and dietary protein in South, East and Southeast Asia. However, uneven pod maturity of mungbean leads to low harvest index and more labor. In this study, we improved genome assembly of cultivated mungbean (V. radiata var. radiata VC1973A) by Pacbio long reads. Total of 557 scaffolds were assembled with N50 length of 5.2 Mb. Total bases of the scaffolds were 475 Mb, which was 87.5% of the estimated mungbean genome size. To anchor the scaffolds to 11 pseudochromosomes, we construct high resolution genetic map by whole genome resequencing of 187 Recombinant Inbred Lines (RILs) derived from a cross between VC1973A and Korean landrace V2984. In addition, quantitative trait loci (QTL) analysis for synchronous maturity of pods was conducted by using single nucleotide polymorphism (SNP) markers used to construct the genetic map. To evaluate synchronous maturity of pods, we collected phenotypic data from 187 RILs. Two QTLs for synchronous maturity were found on chromosome 4 and 7 with LOD scores 2 or higher. The improved genome assembly of mungbean will facilitate genome research and molecular breeding program. Furthermore, newly identified QTLs can help breed elite cultivars with synchronous maturity leading shorter harvesting time, less labor and higher yield.