水稻花粉外壁纹饰特征建立关键基因的功能分析

花粉外壁是花粉表面特有的疏水性结构，在不同植物中呈现出高度多样性的纹饰特征，这种多样性是植物授粉过程中雌雄识别的重要基础之一。孢粉素是花粉外壁的主要化学成分，虽然目前孢粉素合成和转运过程的研究已取得了很大进展，但目前对于孢粉素是在花粉表面形成物种特异性纹饰的具体分子机制了解得还很少。我们分离到了一个水稻不育突变体pad1，表型分析表明该突变体中孢粉素合成和转运没有受到影响，但花粉外壁纹饰不能正常形成。序列分析表明PAD1编码一个禾本科植物所特有的脂类结合蛋白。本项目拟在已有工作基础上，分析PAD1及其同源基因的表达特征、蛋白定位，以及突变后对花粉外壁纹饰形成的影响，提出这些基因控制水稻花粉外壁形成的具体步骤；另外，我们拟对这些蛋白的生化活性,蛋白结构和互作蛋白进行分析，来进一步阐明这些蛋白控制纹饰形成的具体机制。这项研究将为解开植物花粉外壁物种特异性纹饰形成这一科学谜题提供重要线索。

The pollen exine is a hydrophobic multiple-layer outer surface surrounding the pollen grain. The ornamentation pattern of pollen exine is highly variable among different species, which is essential for pollen-stigma recognition and adhesion during pollination. Sporopollenin is the major component of the pollen exine. Many progresses have been made in understanding the mechanism of biosynthesis and translocation of sporopollenin precursors. However, how sporopollenin deposits and forms the species-specific exine ornamentation on the surface of the pollen remains largely unknown. We identified a rice male sterile mutant, designated pad1, which shows normal sporopollenin precursor production and translocation but aberrant pollen exine ornamentation. PAD1 encodes a grass specific lipid binding protein. To understand the molecular mechanism underlying pollen exine pattern formation in grass, we plan to further investigate the function of PAD1 and its homologs. We will analyze gene expression pattern, protein localization and the impact of the absence of PAD1 like genes on the ornamentation pattern formation in grass. In addition, the bioactivity, protein structure and interacting proteins of PAD1 like proteins will be assayed to clarify how they guide the deposition of sporopollenin precursors on the pollen surface. This study will provide clues to solve the scientific mystery of highly variable pollen exine pattern formation.