CmDRM1 negatively regulates lateral bud break in chrysanthemum

The role of sucrose as a signaling molecule in the regulation of shoot branching in plants has been identified. The DRM1/ARP (DORMANCY ASSOCIATED GENE-1/AUXIN-REPRESSED PROTEIN) gene family, which indicates the release of lateral bud dormancy, is significantly associated with lateral bud release. However, the precise mechanisms underlying this regulatory process remain unclear. To determine the mechanisms, we analyzed phenotypic variations in lateral bud growth after sucrose treatment. Through transcriptome sequencing and quantitative analysis, we found a significant association between the DRM1/ARP gene family and lateral bud release. Based on these findings, we speculate that the transport of sucrose to buds and its promotion of lateral bud growth may rely on the auxin pathway. Here, we cloned and analyzed the expression profile of CmDRM1, a downregulated dormancy-associated gene identified from apical buds showing increased sugar levels, based on transcriptome sequencing results. Y1H assays and EMSAs were subsequently conducted to investigate the binding and response of the CmDRM1 promoter to CmARF2. Additionally, overexpression and RNAi techniques were employed to generate transgenic plants with altered levels of CmDRM1. Our findings revealed that the overexpression of CmDRM1 resulted in reduced branching in comparison to that in wild-type plants, while the opposite effect was observed in amiR-CmDRM1-knockdown plants. These results suggest that the key regulatory gene CmDRM1 negatively regulates lateral bud break in chrysanthemum.