CmPP6 and CmMIEL1 interact with CmBBX7 to regulate flowering time in chrysanthemum.
Flowering is a crucial process in the growth and development of plants, playing an essential role in their life cycles. Thus, research into the regulation of flowering time holds significant importance. While CmBBX7 has been identified as a flowering activator regulated by photoperiod, the molecular mechanisms underlying its regulation at the protein level remain unclear. In this study, we utilized yeast two-hybrid screening to identify two proteins that interact with CmBBX7: the phosphatase CmPP6 and the E3 ubiquitin ligase CmMIEL1. Ubiquitination assays confirmed that CmMIEL1 promotes the degradation of CmBBX7, thereby affecting its protein stability and influencing flowering. Genetic evidence indicated that both CmPP6 and CmMIEL1 delay flowering. By interacting with CmBBX7, they indirectly repress the expression of CmFTL1, which is a key flowering gene in chrysanthemum. Our findings provide preliminary evidence that ubiquitin modification affects the stability of the CmBBX7 protein and thereby regulates flowering in chrysanthemum.