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Nature Plants杨维才:NMT测到mlo5/9突变体花粉管钙吸收异常致无法识别胚珠的扩散信号

转自中关村旭月非损伤微测技术产业联盟

Nature Plants | 中科院遗传所杨维才课题组发现花粉管中新的信号通路,揭示其调控花粉管导向的机制


期刊:Nature Plants
主题:MLO整合胚珠信号和Ca2+信号影响花粉管导向
标题:Integration of ovular signals and exocytosis of Ca2+channel by MLOs in pollen tube guidance
影响因子:13.297
检测指标:Ca2+、Cl-、K+流速
检测样品:拟南芥花粉管顶端
NMT实验结论:通过利用NMT测定花粉管尖端的Ca2+流,发现mlo5/9突变体的Ca2+吸收与外排的波动幅度远小于野生型。这说明突变体的Ca2+吸收受到损害,无法定向识别胚珠扩散的信号,从而导致花粉管尖端不向胚珠移动,最终出现败育。而Cl-和K+的流速在二者间无显著差异。
Ca2+、Cl-、K+流实验处理方法:花粉管发芽后即可检测
Ca2+、Cl-、K+流实验测试液成份:Ca2+:0.1 mM KCl, 0.1 mM CaCl2, 1.6 mM H3BO4, 0.05 mM MES Cl-、K+:未提及
作者:中国科学院遗传与发育生物学研究所杨维才、李红菊、孟姜果、梁良

英文摘要

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.

中文摘要(谷歌机翻)

响应细胞外信号,质膜上Ca2+通道的时空调节对于发育,应激反应和繁殖至关重要,但了解甚少。在开花植物繁殖期间,花粉管定向生长到胚珠,胚珠衍生于胚珠衍生的信号并依赖于Ca2+动力学。

然而,尚不清楚卵形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,拟南芥对卵子信号的花粉管响应需要抗微生物位点O5(MLO5),MLO9和MLO15。在表型上不同于先前鉴定的突变体的胚珠旁路表型,mlo5 mlo9双突变体和mlo5 mlo9 mlo15三突变体花粉管在感测到胚珠提示后扭曲并堆积。分子研究表明,MLO5和MLO9通过反式R-SNARE蛋白VAMP721和VAMP722选择性地将含有Ca2+通道CNGC18的囊泡募集到质膜。

这项研究确定了保守的七个跨膜MLO家族的成员(在花粉管中表达)是Ca2+通道的束缚因子,揭示了细胞外卵泡分子的分子整合和选择性胞吐作用的新机制,并阐明了MLO蛋白的一般调控细胞对环境刺激的反应。

图注:mlo5/9(突变型)的Ca2+流速的波动幅度远小于WT(野生型),这说明mlo5/9的Ca2+吸收与外排受到影响,无法定向识别胚珠扩散的信号,影响花粉管导向;而Cl-和K+的流速在二者间无显著差异。正值表示外排,负值表示吸收。

文章链接:https://www.nature.com/articles/s41477-020-0599-1

 

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