Calcium Dependent Protein Kinases in Pollen Tube Tip Growth

该项目的长期目标是了解钙依赖性蛋白激酶（CPK）在调节植物生长和发育的许多方面的功能。 CPK（由一种新结构定义，其中激酶结构域与钙调蛋白样调节结构域融合）似乎是植物和某些单细胞生物所独有的，尚未在动物中发现。在模式植物拟南芥中，有 34 个 CPK，其中 12 个在花粉中表达。虽然许多植物 CPK 被认为参与调节对环境胁迫（如干旱、炎热和寒冷）的反应，但最近获得的遗传证据表明，其中两种 CPK 对花粉管尖端生长至关重要，花粉管尖端生长是一个发育程序。 CPK17 和 34 的基因敲除会导致 1) 花粉管短且生长缓慢，其定位胚珠和使胚珠受精的能力受到破坏，2) 植物基本上不育。通过将 CPK34 基因转移到这些植物中来恢复正常育性的能力为确定对其功能重要的 CPK 特征提供了前所未有的机会。 指导该研究的一个关键假设是 CPK17 和 34 的特定功能是在激酶结构域中编码的。该项目的目标包括 1) 定义这些 CPK 促进花粉管尖端生长和向性的分子途径，2) 描述这些 CPK 调节的细胞过程，从生长的花粉管尖端的胞吞作用和胞吐作用开始，3) 确定这些 CPK 如何调节囊泡运输和细胞骨架动力学，这是极化花粉尖端生长的关键过程。这项研究将为植物系统中钙信号如何编码和解码提供新的见解。 更广泛的影响。该研究将产生来自教育和指导贡献的额外影响。哈珀实验室积极参与从早期职业助理教授到本科生的所有学术层面的指导研究活动。 计划的研究将为本科生和研究生提供分子生物学、共焦显微镜、遗传学和蛋白质组学领域的培训。 项目结果将通过出版物、数据库贡献、科学研讨会以及针对本科生和 K-12 学生的讲座向公众传达。

The long-term goal of this project is to understand the functions of calcium-dependent protein kinases (CPKs) in regulating many aspects of plant growth and development. CPKs (which are defined by a novel structure in which the kinase domain is fused to a calmodulin-like regulatory domain) appear to be unique to plants and certain single-celled organisms, and have not been found in animals. In the model plant Arabidopsis, there are 34 CPKs, 12 of which are expressed in pollen. While many plant CPKs are thought to be involved in regulating the response to environmental stresses, such as drought, heat and cold, recent genetic evidence has been obtained that identifies two of these CPKs as critical to pollen tube tip growth, which is a developmental program. Genetic knockout of CPK17 and 34 results 1) in pollen tubes that are short and slow growing and that are disrupted in their ability to locate and fertilize ovules, and 2) in plants that are essentially sterile. The ability to restore normal fertility by transferring CPK34 genes into these plants provides an unprecedented opportunity to determine the features of a CPK that are important for their functions. A key hypothesis guiding the research is that specific functions of CPK17 and 34 are encoded in the kinase domain. The aims of this project include 1) defining the molecular pathways by which these CPKs promote pollen tube tip growth and tropism, 2) delineating the cellular processes regulated by these CPKs, starting with endocytosis and exocytosis at the tip of a growing pollen tube, and 3) identifying how these CPKs regulate vesicle trafficking and cytoskeletal dynamics, which are critical processes in polarized pollen tip growth. This research will provide new insights into how calcium signals are coded and decoded in plant systems. Broader impacts. The research will have additional impacts that derive from educational and mentoring contributions. The Harper lab is actively engaged in mentoring research activities at all academic levels, from early career assistant professors to undergraduates. The planned research will provide training for both undergraduate and graduate student in the area of molecular biology, confocal microscopy, genetics and proteomics. Project results will be communicated to the public through publications, data base contributions, scientific seminars, and lectures to undergraduates and K-12 students.