Integration of ovular signals and exocytosis of a Ca2+ channel by MLOs in pollen tube guidance
Integration of ovular signals and exocytosis of a Ca2+ channel by MLOs in pollen tube guidance
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花粉管引导中 MLO 的卵细胞信号整合和 Ca2 通道胞吐作用
DOI：
10.1038/s41477-020-0599-1
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发表时间：
2020-02-13
期刊：
影响因子：
18
通讯作者：
Yang, Wei-Cai
中科院分区：
文献类型：
--
作者：
Meng, Jiang-Guo;Liang, Liang;Yang, Wei-Cai
质膜 Ca2+ 通道响应细胞外信号的时空调节对于发育、应激反应和繁殖至关重要，但人们对此知之甚少。在开花植物繁殖过程中，花粉管定向生长到胚珠，这是由胚珠衍生的信号引导并依赖于 Ca2+ 动力学。然而，尚不清楚卵子信号如何与花粉管中的胞质 Ca2+ 动力学整合。在这里，我们表明，防霉基因座 O 5 (MLO5)、MLO9 和 MLO15 是拟南芥花粉管对胚珠信号的反应所必需的。 mlo5 mlo9 双突变体和 mlo5 mlo9 mlo15 三突变体的表型与先前鉴定的突变体的胚珠旁路表型不同，花粉管在感应到胚珠线索后会扭曲并堆积。分子研究表明，MLO5 和 MLO9 通过 R-SNARE 蛋白 VAMP721 和 VAMP722 以反式模式选择性地将含有 Ca2+ 通道 CNGC18 的囊泡招募到质膜上。这项研究确定了保守的七跨膜 MLO 家族（在花粉管中表达）的成员作为 Ca2+ 通道的束缚因子，揭示了细胞外卵泡信号分子整合和选择性胞吐作用的新机制，并揭示了 MLO 蛋白在细胞对环境刺激反应中的一般调节。
The spatiotemporal regulation of Ca2+channels at the plasma membrane in response to extracellular signals is critical for development, stress response and reproduction, but is poorly understood. During flowering-plant reproduction, pollen tubes grow directionally to the ovule, which is guided by ovule-derived signals and dependent on Ca2+dynamics. However, it is unknown how ovular signals are integrated with cytosolic Ca2+dynamics in the pollen tube. Here, we show that MILDEW RESISTANCE LOCUS O 5 (MLO5), MLO9 and MLO15 are required for pollen tube responses to ovular signals in Arabidopsis thaliana. Phenotypically distinct from the ovule-bypass phenotype of previously identified mutants, mlo5 mlo9 double-mutant and mlo5 mlo9 mlo15 triple-mutant pollen tubes twist and pile up after sensing the ovular cues. Molecular studies reveal that MLO5 and MLO9 selectively recruit Ca2+channel CNGC18-containing vesicles to the plasma membrane through the R-SNARE proteins VAMP721 and VAMP722 in trans mode. This study identifies members of the conserved seven transmembrane MLO family (expressed in the pollen tube) as tethering factors for Ca2+channels, reveals a novel mechanism of molecular integration of extracellular ovular cues and selective exocytosis, and sheds light on the general regulation of MLO proteins in cell responses to environmental stimuli.