Pollen-stigma interactions: events and players that set off the path to reproductive success

开花植物的授粉是受精的必要过程。种子和果实的生产、植物物种的保存和多样性的产生都依赖于授粉的成功。这个项目的重点是了解花粉和柱头，雌蕊（雌性生殖器官）上的花粉接受表面如何相互作用以启动授粉。柱头上的第一个事件是花粉萌发，从而产生一个花粉管，它穿透柱头并在雌蕊内伸长，将精子输送到卵子中。休眠花粉粒的激活机制还不清楚。这个过程需要花粉细胞质分布到一个小区域，在那里花粉管从谷粒中出现并生长到雌蕊中，开始一个富有成效的旅程。该项目的重点是获得这些最早的授粉事件的分子理解。柱头和花粉之间的水分转移，以激活花粉粒，细胞质重组的花粉工程管挤出和管生长过程中，和酶，修改花粉和柱头细胞壁，以促进管挤出和其渗透的雌蕊将检查其贡献的早期授粉事件的成功。该项目将培养本科生、硕士、博士。学生和研究生水平的科学家，喂养的研究队伍和未来的领导者在科学的管道。与Girls Inc.合作山谷（霍利奥克马）将带来高中女生的夏季经验为中心的项目研究领域。 近年来，在开花植物生殖过程的分子和细胞理解方面取得了重要进展，特别是在携带精子的花粉如何与雌蕊中的组织相互作用以使受精产生种子方面。重要但未充分探索的是花粉落在雌蕊的接受表面（柱头）上以启动授粉过程的最早事件。该项目的重点是获得这些早期事件的分子和细胞的理解。具体来说，该项目探讨了柱头乳突细胞如何从柱头中调动水来水合干燥和休眠的花粉粒以激活萌发，这涉及从颗粒中挤出极化产物及其发育成花粉管。它还研究了花粉粒如何调动其细胞表面信号和细胞质组分，以协调花粉管挤出和柱头的穿透。在花粉和雌蕊中发生相当大的细胞壁降解和修饰活动，以使萌发和管生长过程成为可能。因此，细胞壁降解酶如何有助于这些过程也将被检查。 该研究以拟南芥为模式系统，依靠分子、转基因、细胞生物学和生物化学相结合的方法。该项目将为从本科到博士后水平的学生提供广泛的科学知识和研究方法的经验，可以广泛应用。将为邻近内城的高中生举办一个与植物繁殖有关的夏季讲习班。分子和细胞生物科学部的细胞动力学和功能小组共同资助该奖项。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Pollination in flowering plants is the requisite process for fertilization. The production of seeds and fruits, preservation of plant species and generating diversity all rely on pollination success. This project focuses on understanding how pollen and stigma, the pollen receptive surface on the pistil (the female reproductive organ) interact to initiate pollination. The first event on the stigma is for the pollen to germinate, thereby generating a pollen tube which penetrates the stigma and elongates inside the pistil to deliver sperm to the egg. The mechanisms underlying the activation of dormant pollen grains are poorly understood. The process requires the pollen cytoplasm to distribute to a small area where a pollen tube emerges from the grain and grows into the pistil to start a fruitful journey. This project focuses on obtaining a molecular understanding of these earliest pollination events. Water transfer between the stigma and pollen to activate the pollen grain, cytoplasmic reorganization in the pollen to engineer the tube extrusion and tube growth process, and the enzymes that modify the pollen and stigma cell walls to facilitate tube extrusion and its penetration of the pistil will be examined for their contribution to the success of the early pollination events. The project will train undergraduates, Master’s, Ph.D. students, and post-graduate level scientists, feeding the pipeline for the research workforce and future leaders in science. A collaboration with Girls Inc. of the Valley (Holyoke MA) will bring high school girls for a summer experience centered on the project research area. Important advances have been made in recent years in the molecular and cellular understanding of the reproduction process in flowering plants, especially in how the sperm-bearing pollen interact with tissues in the pistil to enable fertilization to produce seeds. Important but under-explored are the earliest events which occur upon pollen landing on the receptive surface of the pistil, the stigma, to set off the pollination process. This project focuses on obtaining a molecular and cellular understanding of these early events. Specifically, the project explores how the stigmatic papilla cells mobilize water from the stigma to hydrate a dry and dormant pollen grain to activate germination, which involves the extrusion of a polarized outgrowth from the grain and its development into a pollen tube. It also examines how the pollen grain mobilizes its cell surface signaling and cytoplasmic components to orchestrate pollen tube extrusion and penetration of the stigma. Considerable cell wall degradation and modification activities occur in both the pollen and the pistil to enable the germination and tube growth process. Therefore, how cell wall degradative enzymes contribute to these processes will also be examined. The research uses Arabidopsis as the model system and relies on combined molecular, transgenic, cell biological and biochemical approaches. The project will provide students from undergraduate to postdoctoral levels with a broad range of scientific knowledge and experience in research approaches that can be broadly applied. A summer workshop related to plant reproduction will be developed for high school students from neighboring inner cities. The Cellular Dynamics and Function cluster in the Division of Molecular and Cellular Biosciences is co-funding this award.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.