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>Cellular Pathways Regulating Responses to Compatible and Self-Incompatible Pollen in Brassica and Arabidopsis Stigmas Intersect at Exo70A1, a Putative Component of the Exocyst Complex
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Cellular Pathways Regulating Responses to Compatible and Self-Incompatible Pollen in Brassica and Arabidopsis Stigmas Intersect at Exo70A1, a Putative Component of the Exocyst Complex
n nnnIn the Brassicaceae, compatible pollen–pistil interactionsresult in pollen adhesion to the stigma, while pollen grainsfrom unrelated plant species are largely ignored. There canalso be an additional layer of recognition to prevent self-fertilization,the self-incompatibility response, whereby self pollen grainsare distinguished from nonself pollen grains and rejected. Thispathway is activated in the stigma and involves the ARM repeat–containing1 (ARC1) protein, an E3 ubiquitin ligase. In a screen for ARC1-interactingproteins, we have identified Brassica napus Exo70A1, a putativecomponent of the exocyst complex that is known to regulate polarizedsecretion. We show through transgenic studies that loss of Exo70A1in Brassica and Arabidopsis thaliana stigmas leads to the rejectionof compatible pollen at the same stage as the self-incompatibilityresponse. A red fluorescent protein:Exo70A1 fusion rescues thisstigmatic defect in Arabidopsis and is found to be mobilizedto the plasma membrane concomitant with flowers opening. Bycontrast, increased expression of Exo70A1 in self-incompatibleBrassica partially overcomes the self pollen rejection response.Thus, our data show that the Exo70A1 protein functions at theintersection of two cellular pathways, where it is requiredin the stigma for the acceptance of compatible pollen in bothBrassica and Arabidopsis and is negatively regulated by Brassicaself-incompatibility.展开▼
机译:ABSTRACTn FONT> TH> TR> TABLE> n
n TOP n <字体颜色= 464c53>抽象 FONT> n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n FONT> TH> TR> TABLE> n nnn在十字花科 I>中,相容的花粉-雌蕊相互作用 SUP> re导致花粉粘附到柱头上,而来自无关植物的花粉粒 SUP>却被大大忽略了。可能还有 SUP>识别层,以防止自我受精, SUP>自我不相容反应,从而将自身花粉粒 SUP>与非自身区别开来。花粉粒和拒绝。该 SUP>途径在柱头上被激活,涉及包含ARM重复序列的 SUP> 1(ARC1)蛋白,一种E3泛素连接酶。在筛选与ARC1相互作用的 SUP>蛋白的过程中,我们鉴定出甘蓝型油菜 I> Exo70A1,这是已知的调节囊泡极化的外囊复合物的推定 SUP>成分。 SUP>分泌物。我们通过转基因研究表明,在甘蓝 I>和拟南芥 I>柱头中Exo70A1 SUP>的丧失导致相容花粉的排斥 SUP>与自我不兼容 SUP>响应处于同一阶段。红色荧光蛋白:Exo70A1融合蛋白可挽救拟南芥 I>中的此 SUP>象散缺陷,并发现其与花开放同时被动员了 SUP>到质膜。通过 SUP>进行对比,Exo70A1在自我不相容的 SUP> 芸苔 I>中的表达增加,部分克服了自我花粉排斥反应。 SUP>因此,我们的数据表明,Exo70A1蛋白在两条细胞途径的 SUP>交叉点处起作用,在柱头上需要 SUP>以便接受两个 SUP> 芸苔属植物 I>和拟南芥 I>,并受芸苔属植物 I> SUP>不相容性的负调控。 SUP>
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Department of Cell and Systems Biology, University of Toronto, Toronto, Canada M5S 3B2;
Department of Cell and Systems Biology, University of Toronto, Toronto, Canada M5S 3B2;
Department of Cell and Systems Biology, University of Toronto, Toronto, Canada M5S 3B2;
Department of Cell and Systems Biology, University of Toronto, Toronto, Canada M5S 3B2;
Department of Cell and Systems Biology, University of Toronto, Toronto, Canada M5S 3B2;
Department of Cell and Systems Biology, University of Toronto, Toronto, Canada M5S 3B2|Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Canada M5S 3B2;