OsYABBY6与OsMADS14/15互作调控水稻小花外两轮器官发育的分子机理

The well-known ABC model describes the combinatorial interaction of homeotic genes in specifying floral organ identities. While there is evidence that the B and C functions are highly conserved throughout angiosperm evolution, the status of the A function has been hotly debated. One reason for this is that in most plants that have been investigated thus far, with Arabidopsis being a remarkable exception, one does not find recessive mutants in which the identity of both types of perianth organs is affected. In our previous study, we present a comprehensive mutational analysis of all four members (OsMADS14, OsMADS15, OsMADS18, and OsMADS20) of the AP1/FUL-like subfamily of MADS-box genes in rice, and demonstrate that OsMADS14 and OsMADS15, in addition to their function of specifying meristem identity, are also required to specify palea and lodicule identities. Since these two grass-specific organs are very likely homologous to sepals and petals of eudicots, respectively, we conclude that some kind of a floral homeotic A function also exists in grasses. Furthermore, our result of IP-MS showed that OsYABBY6 is an interaction factor of OsMADS14/15. The arm of the project is to explore in detail the molecular mechanism of the OsYABBY6 function through the genetic, physiological and biochemistry analysis. This study will be helpful for expanding knowledge of the core theory described by ABC model that are mostly made of MADS-box genes.

“ABC”花发育模型阐述了同源异型基因之间的相互作用从而决定各轮花器官特征的形成和发育。该模型理论所涉及到的基因除了拟南芥的AP2外，其余都属于MADS-box基因家族成员。而对于在其他物种中拟南芥AP2直系同源基因是否具有相同的功能几乎未知，更没有实验证据显示其它家族类型基因产物与相关MADS-box蛋白互作参与器官特征决定。我们前期的研究证明OsMADS14和OsMADS15共同作用决定水稻小花外两轮器官（内外稃和浆片）特征的发育；同时IP-MS实验显示OsYABBY6是OsMADS14/15的互作因子，并且突变体表型也表明OsYABBY6参与调控小花外两轮器官特征的决定。本项目申请拟通过进一步解析OsYABBY6的遗传学功能和生理生化功能，以期阐明OsYABBY6与OsMADS14/15互作和对下游目的基因调控的分子机理，拓展以MADS-box为主要成员的花发育ABC模型理论的知识。

我们实验室前期对水稻MADS-box基因家族A类成员OsMADS14和 OsMADS15在花器官发育过程中对花被形成的功能进行了深入和详细的分子遗传学研究，确定了这两个基因在水稻为代表的单子叶植物中的A-功能器官决定作用，从而完善了被子植物花发育ABC模型理论。本项目主要研究内容是在此基础上，利用各种组学方法和分子遗传学技术，例如IP-MS、ChIP-seq、RNA-seq、酵母杂交系统和基因编辑等等，阐明了OsMADS14/15 与OsYABBY6互作方式及其对下游目的基因调控的分子机理，并进一步解析了OsYABBY6的遗传学功能和生理生化功能，建立了OsMADS14/15这两个水稻花发育关键基因的遗传调控网络关系。同时，阐明了OsMADS14在水稻灌浆期对淀粉合成的重要调控作用，为进一步开展水稻产量和品质改良的应用前景提供了理论依据。目前我们正依据这些研究结果撰写数篇论文，其中2篇第一标注的学术论文已经发表在高质量的学术刊物上（New Phytologist, IF: 10.151，2020年和2022年，见成果部分）。