鞘脂类信号物质在植物生殖发育中的作用机理

植物有性生殖研究不但涉及最基本的生命科学问题，还与作物育种、产量紧密相关，因此具有重要的理论意义和巨大应用价值。鞘脂类物质不但构成了细胞膜的重要组分，还是一系列细胞活动的关键信号分子。目前，鞘脂类物质功能研究在动物和酵母中已取得重要进展，但在植物中，尤其在植物有性生殖和发育领域中的作用机理还不清楚。ipod1为一个角果短且种子严重败育的拟南芥突变体，iPOD1基因突变造成花粉管在体内的生长出现异常，iPOD1蛋白具有碱性神经酰胺酶活性。鉴于神经酰胺酶在鞘脂类代谢过程中的核心作用，以及植物有性生殖过程的特殊性，我们将以ipod1等突变体为材料，以拟南芥神经酰胺酶基因为切入点，以植物特有的花粉、花粉管、保卫细胞等为对象，重点关注鞘脂类物质在雌-雄细胞相互作用、花粉管体内生长、ABA信号通路、Ca2+与细胞膨压调控等方面的作用，深入解析该类物质在植物有性生殖及发育中的功能与信号传导机理。

Angiosperms evolved pollen tube to deliver the immobile sperms to embryo sac for double fertilization. Therefore, successful pollen tube growth in vivo is one of the key steps to ensure reproduction efficiency. In vivo elongation of pollen tube depends on the elaborate regulation from pistil and female gametophyte, as well as the normal function of the tube. Mutant ipod1 is defective in pollen tube elongation in vivo and results in poor fertility. Our study on ipod1 indicates that iPOD1 protein acts as a ceramidase, a key enzyme in sphingolipid metabolism. It suggests that sphingolipids are involved in plant sexual reproduction and development. Sphingolipids have been well known as cell membrane components and signal molecules in animal and yeast, however, their function in plant, especially in sexual reproduction and development, is unclear until now. In this project, we will try to unveil the roles that sphingolipids play in female-male cell interaction, pollen tube elongation, ABA signal transduction, Ca2+ and turgor pressure regulation. It is expected that molecular mechanism underlying sphingolipid signaling pathway in plant sexual reproduction and development will be dissected through the proposed study.