The highly variable and species-specific pollen surface patterns are formed by sporopollenin accumulation. The template for sporopollenin deposition and polymerization is the primexine that appears on the tetrad surface, but the mechanism(s) by which primexine guides exine patterning remain elusive. Here, we report that the Poaceae-specific EXINE PATTERN DESIGNER 1 (EPAD1), which encodes a nonspecific lipid transfer protein, is required for primexine integrity and pollen exine patterning in rice (Oryza sativa). Disruption of EPAD1 leads to abnormal exine pattern and complete male sterility, although sporopollenin biosynthesis is unaffected. EPAD1 is specifically expressed in male meiocytes, indicating that reproductive cells exert genetic control over exine patterning. EPAD1 possesses an N-terminal signal peptide and three redundant glycosylphosphatidylinositol (GPI)-anchor sites at its C terminus, segments required for its function and localization to the microspore plasma membrane. In vitro assays indicate that EPAD1 can bind phospholipids. We propose that plasma membrane lipids bound by EPAD1 may be involved in recruiting and arranging regulatory proteins in the primexine to drive correct exine deposition. Our results demonstrate that EPAD1 is a meiocyte-derived determinant that controls primexine patterning in rice, and its orthologs may play a conserved role in the formation of grass-specific exine pattern elements.

高度可变和物种特异性的花粉表面图案是由孢粉蛋白积累形成的。孢粉蛋白沉积和聚合的模板是出现在四面体表面上的primeine，但primexin指导外壁构图的机理仍然难以捉摸。在这里，我们报告说，禾本科特异的EXINE PATTERN DESIGNER 1（EPAD1）编码非特异的脂质转移蛋白，是水稻（Oryza sativa）的primxine完整性和花粉外显子模式所必需的。尽管孢粉蛋白的生物合成不受影响，但EPAD1的破坏会导致异常的外在模式和完全的男性不育。EPAD1在雄性肌母细胞中特异性表达，表明生殖细胞对外在模式发挥遗传控制作用。EPAD1在其C端具有N端信号肽和三个多余的糖基磷脂酰肌醇（GPI）锚定位点，这是其功能和定位在小孢子质膜上所必需的片段。体外测定表明EPAD1可以结合磷脂。我们建议，EPAD1结合的质膜脂质可能参与在primemine中募集和安排调节蛋白以驱动正确的外膜沉积。我们的研究结果表明，EPAD1是控制水稻中primemine模式的源自肌细胞的决定簇，其直系同源物在草特异性exine模式元素的形成中可能起保守作用。体外测定表明EPAD1可以结合磷脂。我们建议，EPAD1结合的质膜脂质可能参与在primemine中募集和安排调节蛋白以驱动正确的外膜沉积。我们的研究结果表明，EPAD1是控制水稻中primemine模式的源自肌细胞的决定簇，其直系同源物在草特异性exine模式元素的形成中可能起保守作用。体外测定表明EPAD1可以结合磷脂。我们建议，EPAD1结合的质膜脂质可能参与在primemine中募集和安排调节蛋白以驱动正确的外膜沉积。我们的研究结果表明，EPAD1是控制水稻中primemine模式的源自肌细胞的决定簇，其直系同源物在草特异性exine模式元素的形成中可能起保守作用。