The RsFLC1 and RsSAM1 gene regulates the bolting time in Radish (Raphanus sativus L.)

Early flowering and bolting of radish can affect the normal development of the underground part's fleshy root, thereby affecting their commercial value. However, the molecular mechanisms underlying flowering time regulation in radish remain largely unexplored. In this study, an F₂ population derived from the cross between the early bolting variety YZH and the late bolting variety XHT. The qBT7.2 locus was fine-mapped to a 171 kb region on chromosome 7 and RsFLC1 was identified as a candidate gene. Overexpression of RsFLC1 significantly delayed flowering time in Arabidopsis. Silencing of RsFLC1 by virus induced gene silencing (VIGS) promoted earlier bolting and flowering in radish, revealing that RsFLC1 acts as a negative regulator of flowering in radish. Totally, 992 DEGs were identified between pTY-RsFLC1-BF (before bolting) and WT-AB (after bolting), 8986 DEGs were detected between pTY-RsFLC1-AB and WT-AB. Luciferase complementation imaging (LCI), pull-down, and bimolecular fluorescence complementation (BiFC) found that RsFLC1 interacts with RsSAM1. Overexpression of RsSAM1 in Arabidopsis exhibited an early-flowering phenotype, while silencing of RsSAM1 in radish have opposite effect. These results offer new understanding of the molecular mechanism underlying late bolting in radish, and provides valuable genetic resources for the breeding of late-bolting varieties in radish.