Cellular signaling mechanisms during pollen-pistil interactions in Brassicaceae

十字花科花粉-雌蕊相互作用过程中的细胞信号机制

• 批准号: RGPIN-2015-04485
• 负责人: Samuel, Marcus
• 金额: $ 2.4万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664213
• 关键词: Cellular; signaling; mechanisms; during; pollen

Plants maintain their yield, vigour and genetic diversity through appropriate selection of genetically diverse mates while rejecting related partners. Given the fact that crop-yield is the most important agronomic trait, understanding the molecular mechanism behind plant reproduction is a major research priority. Successful plant reproduction is dependent on a compatible interaction between the pollen/pollen tube and the pistil. In plant species of Brassicaceae, which are characterized by dry stigmas, only compatible pollen can induce the pistil to provide all the necessary resources for its hydration and penetration into the stigmatic tissue. In contrast, during Brassica (canola, broccoli and cabbage) self-incompatibility (SI) (a selection mechanism to prevent inbreeding), recognition of the self-pollen, induces a highly ordered signaling pathway that rejects the self-pollen (blocks allocation of pistil resources for pollen hydration/germination). During SI response in Brassica, interaction between the pollen and the pistil, leads to recruitment of ARC1 E3 ligase to the proteasome (protein degradation machinery). The targets of ARC1 are proposed to be compatibility factors, which when targeted for degradation by ARC1 results in pollen rejection. My long-term goal is to gain a thorough understanding of the signaling mechanisms that regulate compatible and incompatible pollination events during plant reproduction. Using proteomics approach to identify proteins targeted for destruction following SI response in Brassica stigmas, we identified various metabolic, cytoskeletal and signaling proteins. We have pursued a few of these candidates (Glyoxalase 1 (GLO1), tubulin) and have exciting data that suggest that these proteins are compatibility factors required for successful pollination. The first theme of this proposed research program will focus on determining how the compatibility factor GLO1 is targeted to the proteasome for degradation by the SI response pathway. In addition, the role of methylglyoxal, the cytotoxic metabolite detoxified by GLO1, during SI, will also be addressed using biochemical and molecular approaches. The second major theme is to identify the upstream regulators of MAPKs that we have identified to be involved in mediating compatible pollination. Identification of the activator of these MAPKs would allow us to build the compatible signaling pathway. The third theme is to identify and characterize the phosphatase that controls the phospho-status of MAPKs and one of its likely targets, EXO70A1. Identification of the phosphatase could reveal another mechanism through which SI response could be functioning other than the proteasome-mediated degradation pathway. This research will significantly advance our understanding of the early signaling during pollen-pistil interactions, a key event for successful reproduction. **

植物通过适当选择遗传多样的伴侣在拒绝相关伴侣的同时，保持其产量，活力和遗传多样性。鉴于作物收益是最重要的农艺性状，因此了解植物繁殖背后的分子机制是主要的研究重点。成功的植物繁殖取决于花粉/花粉管与枪口之间的兼容相互作用。在以干污名为特征的黄铜科的植物种类中，只有兼容的花粉才能诱导雌蕊，以提供所有必要的资源，以便其水合并穿透到污名组织中。相比之下，在胸腺（芥末，西兰花和卷心菜）的自我兼容性（SI）期间（一种预防近亲繁殖的选择机制），识别自花胶的识别，诱发了高度有序的信号通路，否定了拒绝自pall胶的高度有序的信号（阻止了对粉状水平/发芽的pistil资源分配）。在Brassica的Si反应过程中，花粉与雌蕊之间的相互作用导致ARC1 E3连接酶募集到蛋白酶体（蛋白质降解机械）。建议ARC1的靶标是兼容因子，当ARC1降解时，会导致花粉排斥。我的长期目标是对调节植物繁殖过程中调节兼容和不兼容的授粉事件的信号传导机制有透彻的了解。使用蛋白质组学方法鉴定诸如Brassica污名后SI反应后针对破坏的蛋白质，我们确定了各种代谢，细胞骨架和信号传导蛋白。我们已经追求了其中一些候选者（乙二醛酶1（GLO1），微管蛋白），并具有令人兴奋的数据，这些数据表明这些蛋白质是成功授粉所需的兼容因素。该提出的研究计划的第一个主题将重点侧重于确定兼容性因子GLO1如何针对SI响应途径降解的蛋白酶体。此外，在Si期间，通过GLO1排毒的细胞毒性代谢产物的甲基甘氨酸的作用也将使用生化和分子方法来解决。第二个主要主题是确定我们已确定参与介导兼容授粉的上游监管机构。这些MAPK的激活剂的识别将使我们能够构建兼容的信号通路。第三个主题是识别和表征控制MAPKS磷酸化状态及其可能目标之一Exo70A1的磷酸酶。磷酸酶的鉴定可以揭示另一种机制，而Si反应除了蛋白酶体介导的降解途径以外的其他机制。这项研究将大大提高我们对花粉杆互动期间早期信号传导的理解，这是成功繁殖的关键事件。 **