Secretory lipid transfer protein OsLTPL94 acts as a target of EAT1 and is required for rice pollen wall development
Secretory lipid transfer protein OsLTPL94 acts as a target of EAT1 and is required for rice pollen wall development
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分泌性脂质转移蛋白 OsLTPL94 作为 EAT1 的靶标，是水稻花粉壁发育所必需的
DOI：
10.1111/tpj.15443
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发表时间：
2021-08-26
期刊：
影响因子：
7.2
通讯作者：
Li, Shuangcheng
中科院分区：
文献类型：
--
作者：
Tao, Yang;Zou, Ting;Li, Shuangcheng
植物花粉壁保护雄性配子体免受各种生物和非生物胁迫。独特的花粉壁结构和精致的外壁图案的形成是一个组织良好的过程，需要生殖细胞和邻近体细胞之间的协调。然而，这一过程背后的分子机制在很大程度上仍然未知。在这里，我们报告了一个水稻雄性不育突变体（1994），它表现出花粉外壁图案缺陷和绒毡层细胞发育异常。MutMap和敲除分析表明，致病基因编码一种g型非特异性脂质转移蛋白（OsLTPL94）。组织学和细胞分析证实，OsLTPL94在发育中的小孢子和绒毡层细胞中强烈表达，其蛋白分泌到质膜上。l94突变阻碍了OsLTPL94蛋白的分泌能力。进一步的体内和体外研究支持了一种假说，即基本螺旋-环-螺旋转录因子（bHLH TF） ETERNAL TAPETUM 1 （EAT1）通过直接结合OsLTPL94启动子的E-box基序激活了OsLTPL94的表达，这一假说得到了两个独立的EAT1突变体中EAT1和OsLTPL94表达呈正相关的支持。我们的研究结果表明，分泌的OsLTPL94在毡层和小孢子的协调发育中发挥关键作用，并通过调控EAT1。
The plant pollen wall protects the male gametophyte from various biotic and abiotic stresses. The formation of a unique pollen wall structure and elaborate exine pattern is a well-organized process, which needs coordination between reproductive cells and the neighboring somatic cells. However, molecular mechanisms underlying this process remain largely unknown. Here, we report a rice male-sterile mutant (l94) that exhibits defective pollen exine patterning and abnormal tapetal cell development. MutMap and knockout analyses demonstrated that the causal gene encodes a type-G non-specific lipid transfer protein (OsLTPL94). Histological and cellular analyses established that OsLTPL94 is strongly expressed in the developing microspores and tapetal cells, and its protein is secreted to the plasma membrane. The l94 mutation impeded the secretory ability of OsLTPL94 protein. Further in vivo and in vitro investigations supported the hypothesis that ETERNAL TAPETUM 1 (EAT1), a basic helix-loop-helix transcription factor (bHLH TF), activated OsLTPL94 expression through direct binding to the E-box motif of the OsLTPL94 promoter, which was supported by the positive correlation between the expression of EAT1 and OsLTPL94 in two independent eat1 mutants. Our findings suggest that the secretory OsLTPL94 plays a key role in the coordinated development of tapetum and microspores with the regulation of EAT1.