AUTHOR=Laosatit Kularb , Amkul Kitiya , Yimram Tarika , Chen Jingbin , Lin Yun , Yuan Xingxing , Wang Lixia , Chen Xin , Somta Prakit 

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

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.852373

DOI=10.3389/fpls.2022.852373

ISSN=1664-462X

ABSTRACT=<p>Seed dormancy in wild mungbean (<italic>Vigna radiata</italic> var. <italic>sublobata</italic>) may be useful for the breeding of cultivated mungbean (var. <italic>radiata</italic>) with pre-harvest sprouting resistance. Previous studies have identified two major quantitative trait loci (QTLs) for seed dormancy, <italic>HsA</italic> and <italic>Sdwa5.1.1</italic>+, 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 <italic>Sdwa5.1.1</italic>+ 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<sub>2</sub> population developed from a cross between ACC41 and KPS2 revealed two linked QTLs, <italic>Sdwa5.1.1</italic>+ and <italic>Sdwa5.1.2</italic>+, controlling seed dormancy. The <italic>Sdwa5.1.1</italic>+ was confirmed in an F<sub>2:3</sub> population derived from the same cross and mapped to a 3.298-Kb region containing only one gene <italic>LOC106767068</italic>, designated as <italic>VrKNAT7-1</italic>, which encodes the transcription factor KNOTTED ARABIDOPSIS THALIANA7 (KNAT7), a class II KNOTTED1-LIKE HOMEOBOX (KNOX II) protein. <italic>VrKNAX7</italic> 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 <italic>VrKNAT7-1</italic> and <italic>VrCYP86A</italic>, a putative downstream regulation of <italic>VrKNAT7-1</italic>, in the seed coat of ACC41 is statistically much higher than that of KPS2. Altogether, these results indicate that <italic>VrKNAT7-1</italic> controls physical seed dormancy in the wild mungbean ACC41.</p>