薛勇彪研究组PLoS Genet解析花器官稳态发育

植物固着生长，因此为了适应多变环境而演化出了多种机制来调节自身的生长发育。在不同的环境条件下植物的营养生长呈现出很高的差异性，即表型可塑性，而生殖生长如花器官发育则呈现出非常稳定的特性，即表型稳态性。但目前控制花器官稳态发育的分子机制还很不清楚。

中国科学院遗传与发育生物学研究所薛勇彪研究组和钱文峰研究组合作通过对水稻eg1突变体的研究，发现eg1突变体在不同的生长环境下花器官呈现显著的表型差异，表明EG1的突变影响了水稻花器官的稳态发育。生理生化实验表明EG1是一个主要在线粒体定位的脂酶，其转录水平、蛋白稳定性和酶活性都具有高温依赖特性。重要的是EG1能够抑制大量下游基因在转录水平对环境的响应，其中包括一系列花器官特性决定基因。进一步的遗传分析证明花器官决定基因OsMADS1, OsMADS6和OsG1作用于EG1的下游来保证花器官的稳态发育。这些结果表明EG1通过介导一条高温依赖的线粒体脂酶途径来保证花器官决定基因的正常表达，进而促进在不同环境中花器官的稳态发育。这一发现揭示了一个调控植物花器官发育的新机制。

该项研究成果于7月1日在线发表在pLoS Genetics杂志（DOI: 10.1371/journal.pgen.1006152）上。薛勇彪研究组博士张碧瑶和钱文峰研究组博士研究生吴少欢为该论文的共同第一作者。该研究得到了中科院分子模块设计育种先导专项和国家“973”项目的资助。

高温下EG1调控水稻花发育稳态的模式图

原文摘要：

A High Temperature-Dependent Mitochondrial Lipase EXTRA GLUME1 promotes Floral phenotypic Robustness against Temperature Fluctuation in Rice (Oryza sativa L.)

The sessile plants have evolved diverse intrinsic mechanisms to control their proper development under variable environments. In contrast to plastic vegetative development, reproductive traits like floral identity often show phenotypic robustness against environmental variations. However, it remains obscure about the molecular basis of this phenotypic robustness. In this study, we found that eg1 (extra glume1) mutants of rice (Oryza savita L.) showed floral phenotypic variations in different growth locations resulting in a breakdown of floral identity robustness. physiological and biochemical analyses showed that EG1 encodes a predominantly mitochondria-localized functional lipase and functions in a high temperature-dependent manner. Furthermore, we found that numerous environmentally responsive genes including many floral identity genes are transcriptionally repressed in eg1 mutants and OsMADS1, OsMADS6 and OsG1 genetically act downstream of EG1 to maintain floral robustness. Collectively, our results demonstrate that EG1 promotes floral robustness against temperature fluctuation by safeguarding the expression of floral identify genes through a high temperature-dependent mitochondrial lipid pathway and uncovers a novel mechanistic insight into floral developmental control.