Isolation and Functional Characterization of a Floral Repressor, , From Pak-choi ( ssp. ).

MADS-box genes form a large gene family in plants and are involved in multiple biological processes, such as flowering. However, the regulation mechanism of MADS-box genes in flowering remains unresolved, especially under short-term cold conditions. In the present study, we isolated , a Pak-choi ( ssp. ) (), as a floral repressor and functionally characterized in and Pak-choi. Subcellular localization and sequence analysis indicated that BcMAF1 was a nuclear protein and contained a conserved MADS-box domain. Expression analysis revealed that had higher expression levels in leaves, stems, and petals, and could be induced by short-term cold conditions in Pak-choi. Overexpressing in showed that had a negative function in regulating flowering, which was further confirmed by silencing endogenous in Pak-choi. In addition, qPCR results showed that expression was reduced and expression was induced in -overexpressing . Meanwhile, transcript was up-regulated and transcript was down-regulated in -silencing Pak-choi. Yeast one-hybrid and dual luciferase transient assays showed that BcMAF1 could bind to the promoters of and . These results indicated that and might be the targets of BcMAF1. Taken together, our results suggested that could negatively regulate flowering by directly activating and repressing .