A Class II KNOX Gene, KNAT7-1 , Regulates Physical Seed Dormancy in Mungbean [ Vigna radiata (L.) Wilczek]

Seed dormancy in wild mungbean ( var. ) may be useful for the breeding of cultivated mungbean (var. ) with pre-harvest sprouting resistance. Previous studies have identified two major quantitative trait loci (QTLs) for seed dormancy, and +, in wild mungbean that are possibly having the same locus or linked. However, these QTLs have not been confirmed/verified and a molecular basis of seed dormancy in mungbean is not yet known. In this study, we aimed to finely map the + and identify candidate gene(s) for this locus. Microscopic observations revealed that wild mungbean "ACC41" seeds had a palisade cuticle layer, while cultivated mungbean "Kamphaeng Saen 2" (KPS2) seeds lacked this layer. Fine mapping using an F population developed from a cross between ACC41 and KPS2 revealed two linked QTLs, + and +, controlling seed dormancy. The + was confirmed in an F population derived from the same cross and mapped to a 3.298-Kb region containing only one gene , designated as , which encodes the transcription factor KNOTTED ARABIDOPSIS THALIANA7 (KNAT7), a class II KNOTTED1-LIKE HOMEOBOX (KNOX II) protein. sequence alignment between ACC41 and KPS2 revealed several polymorphisms in the coding, untranslated, and promoter regions. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression of and , a putative downstream regulation of , in the seed coat of ACC41 is statistically much higher than that of KPS2. Altogether, these results indicate that controls physical seed dormancy in the wild mungbean ACC41.