B and E MADS-box genes determine the perianth formation in Cymbidium goeringii Rchb. f.
First author ：Lin Xiang ；Affiliations：Huazhong Agricultural University（华中农业大学）, Wuhan, China
Corresponding author：：Lin Xiang（向林）
Cymbidium goeringii Rchb. f. is an important ornamental plant with a striking well-differentiated lip. Its complex floral architecture presents an exciting opportunity to examine perianth development. In flowering plants, class A, B and E floral homeotic genes play key roles in the specification of perianth identity. In this study, we used a cDNA library of wild-type C. goeringii flower buds for transcriptome sequencing. Eighteen candidate class A, B and E genes (including AP1/FUL-, AP2-, DEF-, GLO-, SEP-, and AGL6-like genes) were identified. qRT-PCR results showed that CgDEF1, CgSEP2 and CgAGL6-1 were strongly detected only in the sepals and petals (SP), and were significantly down-regulated in the lips. CgDEF3, CgDEF4 and CgAGL6-3 were highly expressed in the lips and lip-like petals, but were only minimally detected in the sepals. Yeast two-hybrid analysis indicated that CgDEF1 and CgGLO formed a heterodimer. CgAGL6-1/CgSEP2 and CgDEF1 formed higher order protein complexes with the assistance of the CgGLO protein, and both CgAGL6-1 and CgSEP2 formed a heterodimer. CgDEF3/CgDEF4 could interact independently with CgGLO and CgAGL6-3, respectively; whilst, CgDEF3 and CgDEF4 also formed heterodimers with the assistance of the CgGLO. Based on a comprehensive analysis relating these gene expression patterns to protein interaction profiles, the mechanism of sepal/petal/lip determination was studied in C. goeringii. Furthermore, a hypothesis explaining the sepal/petal/lip determination of C. goeringii is proposed. The lip-quartet ①(CgDEF3/CgDEF4/CgAGL6-3/CgGLO) promoted lip formation, whereas the sepal/petal-quartet (CgDEF1/CgAGL6-1/CgSEP2/CgGLO) promoted sepal/petal formation. These results enrich the current knowledge regarding the mechanism and pathways of perianth formation in orchids.
春兰是一种重要的观赏植物，唇瓣分化良好。其复杂的花卉结构提供了一个令人兴奋的检查花被的发展的机会。在有花植物中，A、B、E类植物的同源基因在花被鉴定中起着关键作用。在本研究中，我们使用野生型春兰花蕾的cDNA文库进行转录组测序。鉴定了18个候选A、B、E类基因(包括AP1/FUL-、AP2-、DEF-、GLO-、SEP-和agl6样基因)。qRT-PCR结果显示，CgDEF1、CgSEP2和CgAGL6-1仅在萼片和花瓣(SP)中有较强的检测，在唇瓣中有较明显的下调。CgDEF3、CgDEF4和CgAGL6-3在唇瓣和类唇瓣中有较高表达，但在萼片中的检测程度很低。酵母双杂交分析表明，CgDEF1和CgGLO形成一个异源二聚体。CgAGL6-1/CgSEP2和CgDEF1在CgGLO蛋白的辅助下形成了更高阶的蛋白复合物，CgAGL6-1和CgSEP2均形成了异源二聚体。CgDEF3/CgDEF4分别与CgGLO和CgAGL6-3相互作用;而CgDEF3和CgDEF4在CgGLO蛋白的辅助下也形成了异源二聚体。在综合分析这些基因表达模式与蛋白质相互作用的基础上，研究了春兰花萼/花瓣/唇瓣的鉴定机制。此外，还提出了一个假说来解释春兰花萼/花瓣/唇瓣的鉴定。唇瓣四基因(CgDEF3/CgDEF4/CgAGL6-3/CgGLO)促进唇瓣形成，而萼片/花瓣四基因(CgDEF1/CgAGL6-1/CgSEP2/CgGLO)促进萼片/花瓣形成。这些结果丰富了目前关于兰花花被形成的机制和途径的知识。
注：① lip-quartet根据有道词典翻译为“唇瓣四重奏”，quartet也有“四分孢子“的意思，联系上下文，CgDEF3等都是基因名称，所以我把它翻译为“四基因”。
通讯作者：向林
（http://chfs.hzau.edu.cn/info/1041/1190.htm）
个人简介：1998-2002 ，湖南农业大学，本科；2002-2009，华中农业大学，博士。
研究方向：蜡梅花香分子生物学研究；国兰花香及花发育分子生物学研究
doi: https://doi.org/10.1111/ppl.12647
Journal:Physiologia plantarum
Published Date:February 15 ,2018
文章排版idea源自公众号：植物类SCI摘要
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