Floral zygomorphy is thought of as an essential adaptation to specific pollinators. The CYCLOIDEA (CYC)-like genes belonging to the plant-specific TCP transcription factor family are the key regulators of floral zygomorphy. Their expression differentiations bring about diverse forms of floral zygomorphy. However, the regulatory mechanism underlying their expression differentiation remains unknown. In this study, we selected Chirita pumila D. Don, a zygomorphic member of Gesneriaceae, as a model to address this question. Mutant analysis shows that the CYC gene in C. pumila (CpCYC) plays an important role in controlling floral zygomorphy. Further functional investigation of CpCYC intron and 5′ regulatory regions indicates that an 899 bp promoter region is a key determinant of the dorsal-specific expression of CpCYC. In this region, using electrophoretic mobility shift assay and transient expression system, we identified three kinds of cis-regulatory elements with putative binding factors, that is, auxin responsive element, WRKY binding site, LEAFY binding site, and an element with an unknown binding factor. We undertook functional analyses of the two putative LEAFY binding sites, and found that LEAFY could directly activate and regulate CpCYC for its dorsal-specific expression in patterning floral zygomorphy. This research would shed significant light on the regulatory and evolutionary pathways underlying the spatial-specific expression of CYC-like genes for the development of zygomorphic flowers.

中文翻译：

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以 Chirita pumila 为例的 CYC 样基因在形成花的对称性中的调控途径

花对称被认为是对特定传粉媒介的基本适应。属于植物特异性 TCP 转录因子家族的CYCLOIDEA ( CYC ) 样基因是花合子形的关键调控因子。它们的表达差异带来了多种形式的花合子形。然而，它们表达分化的调控机制仍然未知。在这项研究中，我们选择了苦苣苔科的左右型成员Chirita pumila D. Don 作为解决这个问题的模型。突变分析表明，CYC基因Ç。荔（CPCYC) 在控制花的对称性方面起重要作用。CpCYC内含子和 5' 调控区的进一步功能研究表明 899 bp 启动子区域是CpCYC背侧特异性表达的关键决定因素。在该区域，通过电泳迁移率变化分析和瞬时表达系统，我们鉴定了三种具有推定结合因子的顺式调控元件，即生长素响应元件、WRKY结合位点、LEAFY结合位点和未知结合元件。因素。我们对两个假定的 LEAFY 结合位点进行了功能分析，发现 LEAFY 可以直接激活和调节CpCYC因为它在形成花的左右对称性中的背侧特异性表达。这项研究将为左右对称花发育的CYC样基因空间特异性表达的调控和进化途径提供重要启示。