生长素对雌配子体珠心降解的调控机理

The development of female gametophyte (FG) is the basis of plant double fertilization. Nucellus is the maternal tissue, which surrounds FG and degenerates with FG development to provide more necessary space for FG enlargement, and therefore is regarded as a critical tissure in coodinating development and communication between maternal and filial tissue during FG development. Then the underlying mechanism of nucellus degeneration keep in largely unknown and prevent our understanding on the coordinate development and communication between maternal anf filial tissue. Our previous study showed that the nucellus degeneration is regulated by the auxin, and depend on the auxin gradients in nucellus. Further observation suggested the auxin efflux carriers (PINs) plays critical role in the auxin gradients formation and nucellus degeneration. This proposal, therefore, focus on the roles of PINs in auxin gradients formation and nucellus degeneration with genetic and cytologic approaches, to clarify the specific function of PINs in auxin transportation of mucellus and in nucellus degeneration. Corresponding results will provide the underlying mechanism of auxin gradients formation and coordinate development between maternal tissue, and the foundation to further study communication between maternal and filial tissue during FG development.

雌配子体的发育是植物双受精的基础。珠心是雌配子体中包裹胚囊，并随雌配子发育逐步降解的母体组织，对雌配子体发育中母体与子体间交流，以及他们的协同发育具有重要作用，但珠心在雌配子体发育中降解的调控机理目前尚不清楚，是当前植物雌配子体发育研究中的较为薄弱的环节，限制了雌配子体发育中母体与子体协同发育与相互交流的认识。申请人的前期研究结果表明珠心细胞的有序降解受到生长素的调控，且依赖于珠心细胞中的生长素浓度梯度。进一步的观察表明，珠心中的生长素浓度梯度的形成与珠心细胞的降解需要生长素运输载体PINs的参与。基于这些结果，本项目拟对参与珠心生长素浓度梯度形成的PINs在珠心降解中的功能开展系统的遗传学与细胞学的研究，以解析珠心细胞生长素浓度梯度形成的分子基础及对珠心降解过程的调控，提供雌配子体中母体与子体协同发育的分子基础，也为进一步研究雌配子体发育过程中母体与子体间的信号交流奠定基础。

雌配子体的发育是植物双受精的基础。本项目计划分析生长素调控雌配子体周围珠心降解的分子机理，通过观察表明珠心细胞存在明显的生长素浓度梯度，该梯度是控制珠心细胞有序降解的关键信号；生长素外流载体PINs是控制珠心组织中生长素浓度梯度与雌配子体发育的关键蛋白，从而解析珠心细胞生长素浓度梯度形成的分子基础，为母体和子代的协调发育提供信号交流机制。在项目获批后，进展较为顺利，完成了项目书中计划的全部研究目标，在New phytologist发表文章1篇，申请专利1项。同时在研究中进一步发现，植物在胁迫下诱导的一氧化氮会抑制植物珠心细胞中生长素的运输，从而控制着雌配子体的发育进程，而外源的生长素供应可以加速雌配子体在逆境胁迫下的发育进程，从而提高植物在逆境胁迫下的结实率，并由此将项目拓展到逆境胁迫调控植物雌配子体发育的领域。