Inheritance and a major quantitative trait locus of seed starch content in mungbean (Vigna radiata (L.) Wilczek)

Mungbean (Vigna radiata) seeds are used for direct consumption by people and are raw material for sprout, starch and noodle industries in Asia. High-yielding mungbean cultivars with high seed starch content are preferred for the starch and noodle industries. At present, there is no report on genetic control of seed starch content in mungbean. The objective of this study were to (i) estimate heritability of the starch content in mungbean and (ii) locate a major quantitative trait locus (QTL) controlling starch content. An F-2 population of 123 individuals was developed from the cross V6087AG (high seed starch) x V5020BY (low seed starch). Seeds of F-2 and F-2:3 populations were determined for seed starch content. Broad-sense heritability estimated for seed starch content in the F-2 and F-2:3 populations were higher than 80%. Seed starch content showed a relatively high and significant correlation (r = 0.6) with seed weigh in both F-2 and F-2:3 populations. Bulk segregant analysis using 123 polymorphic SSR markers revealed that only SSR marker CEDG092 on mungbean chromosome 8 associated with the starch content. QTL mapping using CEDG092 and 22 newly developed SSR markers the chromosome confirmed that a major QTL, qSSC8.1, flanked by markers Vr08-SSR113 and Vr08-SSR114 control seed starch content in both F-2 and F-2:3 populations. qSSC8.1 showed no localization with seed weight QTL and explained about 12.34-13.84% of total variation of the seed starch content in the two populations. Allele(s) from V6087AG at this QTL increased seed starch content. Vr08-SSR113 and Vr08-SSR114 spanned a genome region of about 385 Kbp and there were 21 annotated genes in this region. This genome region can be used as target for fine mapping to identify gene controlling seed starch content in mungbean.