Cellular signaling mechanisms during pollen-pistil interactions in brassicaceae

开花植物不能控制落在柱头上的花粉粒的类型，并有适当的识别机制来接受或拒绝花粉。植物的成功繁殖依赖于花粉/花粉管与雌蕊之间的相容相互作用。在以干柱头为特征的芸苔科植物物种中，只有相容的花粉才能诱导雌蕊为其水化和渗透到柱头组织中提供所有必要的资源。相比之下，在芸苔属植物（油菜、西兰花和卷心菜）的自交不亲和（SI）（一种防止近亲繁殖的选择机制）中，对自交花粉的识别诱导了一个高度有序的信号机制，拒绝自交花粉（阻碍了花粉水化/萌发的雌蕊资源分配）。尽管在了解植物受精方面取得了令人兴奋的进展，但对花粉/雌蕊相互作用的早期信号机制的了解仍然有限。我的长期目标是深入了解植物繁殖过程中调节亲和性授粉的信号机制，并绘制亲和性和不亲和性途径之间的相互作用。通过研究芸苔属植物的自交不亲和性，我们发现自交不亲和性针对的是相容花粉接受所需的胞外分泌介导的分泌事件。在蛋白质组学筛选中，我们发现磷脂酶d - α 1 （PLD1）和膜联蛋白1 (ANX1)（已知的胞外分泌调节因子）都是SI的靶标。本研究计划的主要重点是研究PLD1和ANX1在芸苔属亲和授粉事件中的功能作用，并阐明SI靶向这些蛋白的机制。第二个方面是了解它们在调节模式植物拟南芥（芸苔科的一种自交物种）的相容授粉方面的功能是如何保守的，其中这些蛋白质是由基因家族代表的。这项研究将大大提高我们对花粉-雌蕊相互作用早期信号的理解，这是成功繁殖的关键事件。了解植物繁殖使我们能够制定提高作物产量的策略。

Flowering plants cannot control the type of pollen grains that land on its stigma and have appropriate recognition mechanisms to either accept or reject the pollen. 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 a 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 mechanism that rejects the self-pollen (blocks allocation of pistil resources for pollen hydration/germination). Despite the exciting progress made in understanding plant fertilization, knowledge is still limited about the early signaling mechanisms during pollen/pistil interactions. My long term goal is to gain a thorough understanding of the signaling mechanisms that regulate compatible pollination during plant reproduction and to map the interplay between the compatibility and incompatibility pathways. Through studying self-incompatibility in Brassica, we identified that SI targets the exocytosis-mediated secretory events that are required for compatible pollen acceptance. In a proteomics screen to identify factors regulated by SI, we identified that both phospholipase D-alpha 1 (PLD1) and annexin1 (ANX1) (known regulators of exocytosis) are targeted by SI. The primary focus of this research program is to study the functional role of both PLD1 and ANX1 during compatible pollination events in Brassica and to elucidate the mechanism by which SI targets these proteins. The second aspect is to understand how conserved their functions are in regulating compatible pollination in the model plant Arabidopsis thaliana (a self-fertile species of Brassicaceae), where these proteins are represented by gene families. This research will significantly advance our understanding of early signaling during pollen-pistil interactions, a key event for successful reproduction. Understanding plant reproduction allows us to develop strategies to improve crop yield.