Cellular signalling 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-2020-05301
• 负责人: Samuel, Marcus
• 金额: $ 3.42万
• 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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716452
• 关键词: Cellular; signalling; mechanisms; during; pollen

Plants maintain their yield, vigour and genetic diversity through appropriate selection of genetically diverse mates while rejecting related partners. In most flowering plants, successful reproduction is controlled at the earliest stages of pollination when the pollen interacts with the stigmatic papillary cell of the female. Following a favourable (compatible) interaction between the pollen and the stigma, the pollen tube grows through the style and fertilizes the ovule. In contrast, to avoid genetically similar mates (self-pollen), plants utilize self-incompatibility (SI) system as a genetic barrier to prevent self-pollen from developing on the stigma, allowing development of only cross-pollen, thereby promoting hybrid vigour and diversity. During SI response in Brassica, interaction between the pollen (male) ligand SCR/SP11 and the stigma (female) SRK (receptor kinase), leads to recruitment of ARC1 E3 ligase to the proteasome, where ARC1 facilitates degradation of various downstream compatibility factors. We have characterized at least three of these downstream targets and their role in pollination. My long-term goal is to gain a thorough understanding of the signaling mechanisms that regulate compatible and incompatible pollination events during plant reproduction. Three specific research objectives are described. 1) Our preliminary evidence suggests that MAPKs (mitogen-activate protein kinases) are constitutively activated in the stigmas and are required for mediating compatible pollination. We propose to identify the upstream regulators of MAPKs that are involved in mediating compatible pollination. Identification of the activator(s) of these MAPKs would allow us to build the compatible signaling pathway 2) Elucidate the signaling mechanism behind activation of Exo70A1 during pollination. The role of MAPKs in influencing the function of Exo70A1 through phosphorylation will be assessed. This objective will lead to completion of the pathway downstream of MAPKs that is required for compatible interactions 3) Characterizing JDP1 (J-domain protein) as a positive regulator of SI. Although a number of targets of ARC1 have been identified, no other positive regulator of SI pathway has been identified after ARC1. JDP1 can interact with ARC1 and suppression of JDP1 leads to breakdown of SI, suggesting JDP1 is a positive regulator of SI. We propose to use transgenic, molecular and biochemical approaches to elucidate how JDP1 participates in SI signaling. Given that crop-yield in most of our staple foods impinge on successful reproduction, understanding the genetic networks that drive the reproductive potential of a crop plant is crucial for our global move toward sustainability. Our research program aims to address this from both a discovery and an applied perspective. The HQPs trained through this program will have a unique advantage of finding jobs in the canola industry and will have opportunities in academia, industry and the government.

植物通过适当选择遗传多样性的配偶同时拒绝相关配偶来保持其产量、活力和遗传多样性。在大多数开花植物中，成功的繁殖是在授粉的最早阶段控制的，此时花粉与雌性的柱头乳头细胞相互作用。在花粉和柱头之间有利（相容）的相互作用之后，花粉管穿过花柱生长并使胚珠受精。相反，为了避免遗传上相似的交配（自花粉），植物利用自交不亲和（SI）系统作为遗传屏障，阻止自花花粉在柱头上发育，只允许异花花粉发育，从而促进杂种活力和多样性。在芸苔属 SI 反应期间，花粉（雄性）配体 SCR/SP11 和柱头（雌性）SRK（受体激酶）之间的相互作用，导致 ARC1 E3 连接酶募集到蛋白酶体，其中 ARC1 促进各种下游相容性因子的降解。我们已经描述了至少三个下游目标及其在授粉中的作用。 我的长期目标是全面了解植物繁殖过程中调节相容和不相容授粉事件的信号机制。描述了三个具体的研究目标。 1）我们的初步证据表明，MAPK（丝裂原激活蛋白激酶）在柱头中被组成型激活，并且是介导相容授粉所必需的。我们建议确定参与介导相容授粉的 MAPK 上游调节因子。识别这些 MAPK 的激活剂将使我们能够构建兼容的信号传导途径 2) 阐明授粉期间 Exo70A1 激活背后的信号传导机制。将评估 MAPK 通过磷酸化影响 Exo70A1 功能的作用。这一目标将导致 MAPK 下游途径的完成，这是兼容相互作用所需的 3) 将 JDP1（J 结构域蛋白）表征为 SI 的正调节因子。尽管已经确定了ARC1的许多靶标，但在ARC1之后尚未确定SI途径的其他正调节因子。 JDP1 可以与 ARC1 相互作用，抑制 JDP1 会导致 SI 崩溃，表明 JDP1 是 SI 的正调节因子。我们建议使用转基因、分子和生化方法来阐明 JDP1 如何参与 SI 信号传导。 鉴于我们大多数主食中的作物产量都会影响成功的繁殖，了解驱动农作物繁殖潜力的遗传网络对于我们全球迈向可持续发展至关重要。我们的研究计划旨在从发现和应用的角度解决这个问题。通过该项目培训的总部人员将拥有在油菜籽行业寻找工作的独特优势，并将在学术界、工业界和政府部门获得机会。