Fine-Mapping of qECL7.1, a Quantitative Trait Locus Contributing to Epicotyl Length in Adzuki Bean (Vigna angularis)

Abstract

Increasing the epicotyl length (ECL) of adzuki bean cultivars enhances the suitability for mechanical weeding during the vegetative stages and harvesting at pod maturity. To explore the genetic control of ECL, and to identify molecular markers that could facilitate breeding for increased ECL, recombinant inbred lines (RILs) were developed from a cross between Toiku161 (long epicotyls) and Chihayahime (ordinary length epicotyls). In this study, four quantitative trait loci (QTLs) were identified for ECL by QTL-seq analysis, one each on chromosomes 2, 7, 10 and 11. Insertion and deletion (InDel)-based mapping also detected QTLs on chromosomes 7, qECL7.1, and 10, qECL10.1. Substitution mapping using InDel, cleaved amplified polymorphic sequence (CAPS), derived cleaved amplified polymorphic sequence (dCAPS), and single nucleotide polymorphism (SNP) markers narrowed the chromosomal location of qECL7.1 to a 418 kb region flanked by DNA markers TC99_10,211,134 bp and TC102_10,628,880 bp. A total of 35 genes were predicted within the qECL7.1 region. The ECL QTLs and molecular markers identified here will contribute towards marker-assisted selection of desirable long ECL genotypes that allow for increased mechanization and more efficient adzuki bean production.