The complex capitulum of Chrysanthemum morifolium is often comprised of bilaterally symmetrical ray florets and radially symmetrical disc florets. The TCP transcription factor clade CYCLOIDEA2 (CYC2) appears to play a vital role in determining floral symmetry and in regulating floral organ development in Asteraceae. Our previous study identified six CmCYC2 genes from chrysanthemum and showed that CmCYC2c participated in the regulation of ray floret identity. However, the functions of other CmCYC2 genes and the underlying molecular mechanism of CmCYC2-mediated floral development regulation in chrysanthemums have not been elucidated. In this study, we analysed the function of CmCYC2 genes by ectopic expression of CmCYC2 in Arabidopsis. Then, we examined the protein-protein interaction using yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. Finally, we analysed the protein-DNA interaction using yeast one-hybrid (Y1H) and dual-luciferase reporter assays. We found that ectopic expression of CmCYC2 genes in the Arabidopsis tcp1 mutant changed its floral symmetry and flowering time. Y2H and BiFC assays confirmed three pairs of interactions between CmCYC2 proteins, that is, CmCYC2b-CmCYC2d, CmCYC2b-CmCYC2e and CmCYC2c-CmCYC2d, suggesting that heterodimeric complexes may form between CmCYC2 proteins to increase their functional specificity. The results of Y1H and dual-luciferase reporter assays indicate that CmCYC2c can bind to the promoter of ClCYC2f. Our findings provided clues that CmCYC2-like transcription factors may interact with each other or bind to the promoter to regulate floral symmetry development in C. morifolium. KEY MESSAGE: CmCYC2-like transcription factors may interact with each other or bind to the promoter to regulate floral symmetry development in Chrysanthemum morifolium.

中文翻译：

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类似于CmCYC2的转录因子可以彼此相互作用或与启动子结合，从而调节菊花的花对称性发育。

菊花的复杂花序通常由两侧对称的射线小花和径向对称的圆盘小花组成。TCP转录因子进化枝CYCLOIDEA2（CYC2）似乎在决定花的对称性和调节菊科的花器官发育中起着至关重要的作用。我们先前的研究从菊花中鉴定了六个CmCYC2基因，并表明CmCYC2c参与了射线小花身份的调控。但是，尚未阐明其他CmCYC2基因的功能和CmCYC2介导的菊花花卉发育调控的潜在分子机制。在这项研究中，我们通过异位表达CmCYC2在拟南芥中分析了CmCYC2基因的功能。然后，我们使用酵母双杂交（Y2H）和双分子荧光互补（BiFC）分析方法检查了蛋白质与蛋白质的相互作用。最后，我们使用酵母一杂交（Y1H）和双荧光素酶报告基因分析法分析了蛋白质与DNA的相互作用。我们发现在拟南芥tcp1突变体中CmCYC2基因的异位表达改变了其花的对称性和开花时间。Y2H和BiFC分析证实了CmCYC2蛋白之间的三对相互作用，即CmCYC2b-CmCYC2d，CmCYC2b-CmCYC2e和CmCYC2c-CmCYC2d，这表明CmCYC2蛋白之间可能形成异二聚体复合物以增加其功能特异性。Y1H和双荧光素酶报告基因测定的结果表明CmCYC2c可以结合ClCYC2f的启动子。我们的发现提供了线索，表明CmCYC2样转录因子可能彼此相互作用或与启动子结合，从而调节mo叶植物的花对称发育。关键信息：类似于CmCYC2的转录因子可能彼此相互作用或与启动子结合，从而调节菊花的花对称性发育。