Grass-Specific EPAD1 Is Essential for Pollen Exine Patterning in Rice
Grass-Specific EPAD1 Is Essential for Pollen Exine Patterning in Rice
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草特异性 EPAD1 对于水稻花粉外壁图案形成至关重要。
DOI：
10.1105/tpc.20.00551
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发表时间：
2020-12-01
期刊：
影响因子：
11.6
通讯作者：
Liang, Wanqi
中科院分区：
文献类型：
--
作者：
Li, HuanJun;Kim, Yu-Jin;Liang, Wanqi
水稻脂类结合蛋白EPAD 1是一种雄性减数分裂细胞衍生的决定子，它通过维持花粉外壁的完整性来控制禾本科植物花粉外壁的形成，花粉外壁的高度变异和物种特异性是由花粉素积累形成的。孢粉素沉积和聚合的模板是出现在四分体表面的primexine，但primexine引导外壁图案化的机制仍然难以捉摸。在这里，我们报告说，Poaceae特定的外壁模式识别器1（EPAD 1），它编码一种非特异性的脂质转移蛋白，是所需的primexine完整性和花粉外壁图案在水稻（水稻）。EPAD 1的破坏导致异常外壁模式和完全雄性不育，尽管孢粉素生物合成不受影响。EPAD 1在雄性性母细胞中特异性表达，表明生殖细胞对外壁图案形成施加遗传控制。EPAD 1在其N端有一个信号肽，在C端有三个多余的糖基磷脂酰肌醇（GPI）-锚位点，这是其功能和定位于小孢子质膜所需的片段。体外试验表明EPAD 1可以结合磷脂。我们建议，质膜脂质结合EPAD 1可能参与招聘和安排在primexine的调节蛋白，以驱动正确的外壁沉积。我们的研究结果表明，EPAD 1是一个减数分裂细胞衍生的决定因素，控制primexine图案在水稻，其直系同源物可能发挥保守的作用，在形成草特异性外壁图案元素。
Rice lipid binding protein EPAD1 is a male meiocyte-derived determinant that controls grass-specific pollen exine pattern formation by maintaining primexine integrity.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.