CAREER: Molecular Mechanisms of Plant Cell Tip Growth

研究活动：茎尖生长是植物细胞生长的一种形式，虽然仅限于少数细胞类型，但对于从藻类到开花植物的植物物种的发育至关重要。 特别是在种子植物中，顶端生长的花粉管是受精和繁殖所必需的。根毛对于整个植物生长和发育所需的水和矿物质的吸收是重要的。该项目将专注于破译控制尖端生长的分子信号，从而影响植物细胞发育的进化范围。这项研究将在一个新兴的植物模型系统中进行，苔藓小立碗藓。分子遗传操作的容易性和尖端生长细胞的丰富性使苔藓成为这些研究的理想选择。苔藓系统在植物中因其基因靶向能力而独特。此外，Bezanilla博士最近开发了一种快速的RNA干扰试验，它可以快速揭示植物基因的功能，在任何植物系统中都是无与伦比的。Bezanilla博士发现，参与肌动蛋白细胞骨架网络的某些蛋白质对尖端生长至关重要。这些研究已经导致了一个工作模型，其中生长极化是由源自植物特异性小GTTR 0 P的激活的分子信号传导级联控制的，所述小GTTR 0 P继而经由肌动蛋白丝的细胞成核剂formins向肌动蛋白单体结合蛋白profilin发出信号，从而协调肌动蛋白动力学在生长位点发生。该项目将使用反向遗传学，动态活细胞成像和分子相互作用筛选的组合来测试该模型。本报告将探讨三个主要问题：（1）人事登记制度如何规管？(2)formins在ROP-profilin通路中起作用吗？ROP-profilin通路的分子组成是什么？许多生物，包括真菌和动物，通过类似的信号级联控制细胞形态发生。因此，这项研究将提供新的比较深入了解这一进化保守的过程。更广泛的影响：该项目具有潜在的农业效益的社会。通过阐明控制植物细胞尖端生长的基本机制，这项研究将影响对重要植物细胞类型的理解，这些细胞类型参与决定整体植物适应性，从而决定作物产量。该项目还将把研究与教学和培训结合起来，并将扩大代表性不足的群体对科学的参与。Bezanilla博士本人是科学界代表性不足的少数民族的一员，她招募并指导了一位优秀的少数民族博士后研究人员。Bezanilla博士还将开发一门关于苔藓方法的课程，该课程将在马萨诸塞州大学以及通过NSF资助的东北研究生教育联盟和教授会在合作伙伴少数民族服务机构教授，以进一步加强科学中代表性不足的群体的招聘。

Research Activity: Tip growth is a form of plant cell growth that although restricted to a few cell types, is essential for the development of plant species ranging from algae to flowering plants. In seed plants in particular, the tip-growing pollen tube is required for fertilization and thus propagation of the species. The root hair is important for absorption of water and minerals required for growth and development of the entire plant. This project will focus on deciphering the molecular signals that control tip growth, thus impacting an evolutionarily wide range of plant cell development. The research will be carried out in an emerging plant model system, the moss Physcomitrella patens. The ease of molecular genetic manipulation and the abundance of tip growing cells make moss ideal for these studies. The moss system is unique among plants for its gene-targeting capabilities. Additionally Dr. Bezanilla recently developed a rapid RNA interference assay, which rapidly reveals plant gene function and is unparalleled in any plant system. Using this assay, Dr. Bezanilla found that certain proteins participating in the actin cytoskeletal network are critical for tip growth. These studies have lead to a working model whereby growth polarization is controlled by a molecular signaling cascade stemming from activation of the plant-specific small GTPase ROP, which in turn signals to the actin monomer binding protein profilin via formins, cellular nucleators of actin filaments, thus coordinating actin dynamics to occur at the site of growth. The project will test this model using a combination of reverse genetics, dynamic live-cell imaging, and molecular interaction screens. Three major questions will be addressed: (1) How is ROP regulated? (2) Do formins function in the ROP-profilin pathway? and (3) What is the molecular composition of the ROP-profilin pathway? Many organisms, including fungi and animals, control cellular morphogenesis via a similar signaling cascade. Thus this research will provide novel comparative insights into this evolutionarily conserved process.Broader Impacts: This project has potential agricultural benefits for society. By elucidating the fundamental mechanisms controlling plant cell tip growth, this research will impact the understanding of important plant cell types, which are involved in determining overall plant fitness and thus crop yields. The project will also integrate research with teaching and training and will broaden the participation of underrepresented groups in science. Dr. Bezanilla, herself a member of an underrepresented minority in science, has recruited and mentored an excellent minority postdoctoral researcher. Dr. Bezanilla will also develop a course on moss methods that will be taught both at the University of Massachusetts as well as at partner minority serving institutions through an NSF-funded Northeast Alliance for Graduate Education and the Professoriate to further enhance recruitment of underrepresented groups in science.