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，并且有适当的识别机制来接受或拒绝花粉。成功的植物繁殖依赖于花粉/花粉管和雌蕊之间的相互作用。在以柱头干燥为特征的十字花科植物中，只有亲和的花粉才能诱导雌蕊为其水合作用和穿透柱头组织提供所有必要的资源。相反，在甘蓝(油菜、花椰菜和甘蓝)自交不亲和(一种防止近亲交配的选择机制)期间，自交花粉的识别诱导了一种高度有序的信号机制，该机制拒绝自交花粉(阻止用于花粉水合/萌发的雌蕊资源的分配)。尽管在理解植物受精方面取得了令人振奋的进展，但对花粉/雌蕊相互作用过程中的早期信号机制的了解仍然有限。我的长期目标是彻底了解植物繁殖过程中调节亲和授粉的信号机制，并绘制亲和和不亲和途径之间的相互作用图。通过对甘蓝型油菜自交不亲和性的研究，我们确定了SI的靶标是胞吐作用介导的分泌事件，这是亲和接受花粉所必需的。在确定SI调节因子的蛋白质组学筛选中，我们发现磷脂酶D-α1(PLD1)和膜联蛋白1(ANX1)(已知的胞吐调节因子)都是SI的靶标。本研究的重点是研究PLD1和ANX1在甘蓝型油菜亲和授粉过程中的功能作用，并阐明SI针对这些蛋白的机制。第二个方面是了解它们在模式植物拟南芥(十字花科自育物种)中调节亲和授粉的功能是如何保守的，在模式植物中，这些蛋白是由基因家族代表的。这项研究将极大地促进我们对花粉-雌蕊相互作用中早期信号的理解，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.