COLLABORATIVE RESEARCH: Establishing the microtubule-actin crosstalk in the preprophase band by the rice kinesin OsKCH2

该项目研究调节水稻细胞分裂和生长的基本机制，预计将产生广泛的社会影响。首先，这个项目的发现将影响水稻的未来育种，而水稻养活了世界上一半的人口。其次，俄勒冈州立大学和加州大学戴维斯分校的科学家将通过参与以发现为导向的研究，在多学科领域接受培训。第三，该项目包含基于光学显微镜的短期课程和实践培训机会，这将激发他们对STEM学科的兴趣。此外，为了提高公众对前沿研究项目的认识，植物运动蛋白将被包括在高中和社区大学科学教师的高级光学显微镜研讨会上作为活生生的例子。具体来说，本项目旨在研究OsKCH2（一种水稻植物特异性驱动蛋白）如何使微管（MTs）和丝状动作蛋白（f - actiins）在皮质分裂位点之间产生串扰，以及它如何调节细胞分裂。运动蛋白是一种运动蛋白，它利用ATP水解产生的能量为许多基本的细胞过程提供动力，例如沿着mt运输货物和组织/重塑生理上重要的基于mt的阵列。OsKCH2是高等植物中具有钙钙蛋白同源结构域（Calponin Homology domain, KCHs）的运动蛋白。已知KCHs在体外交联mt和F-actin，但它们在植物生长发育中的功能仍然知之甚少。该项目基于几个关键的初步发现，包括：(1)OsKCH2突变导致侏儒症表型，(2)OsKCH2在有丝分裂早期与PPB特异性相关，(3)OsKCH2在体外直接结合并在微管上运输F-actin，以及(4)OsKCH2是第一个负端定向的运动蛋白-14作为单一二聚体表现出进程运动性。该项目将采用多学科的方法来实现两个目标：(1)利用体外单分子成像技术剖析OsKCH2遗传动力的调控机制；(2)通过检测与零kch2突变相关的表型，研究OsKCH2在细胞分裂和植物生长中的体内功能。

This project studies the fundamental mechanisms that regulate cell division and growth of the rice plant and is expected to have a broad spectrum of societal impacts. First, findings from this project will impact future breeding of rice, which feeds half of the world's population. Second, scientists at both Oregon State University and University of California in Davis will be trained in multi-disciplinary areas by participating in the discovery-oriented research. Third, this project contains light microscopy-based short courses and hands-on training opportunities for underserved students, which will stimulate their interests in STEM disciplines. In addition, to increase public awareness of cutting-edge research programs, plant motor proteins will be included as living examples in advanced light microscopy workshops for high school and community college science teachers.Specifically, this project is aimed at investigating how OsKCH2, a plant-specific kinesin in the rice plant Oryza sativa, enables the crosstalk between microtubules (MTs) and filamentous actins (F-actins) at the cortical division site and how it regulates cell division. Kinesins are motor proteins that use the energy from ATP hydrolysis to power numerous essential cellular processes such as transporting cargos along MTs and organizing/remodeling physiologically important MT-based arrays. OsKCH2 belongs to the group of Kinesins with a Calponin Homology domain (KCHs) in high plants. KCHs are known to crosslink MTs and F-actin in vitro, but their functions in plant growth and development remain poorly understood. The project is based on several critical preliminary findings including: (1) mutations in OsKCH2 caused a dwarfism phenotype, (2) OsKCH2 is specifically associated with the PPB during early stages of mitosis, (3) OsKCH2 directly binds to and transports F-actin on microtubules in vitro, and (4) OsKCH2 is the first minus end-directed Kinesin-14 to demonstrate processive motility as a single dimer. This project will use a multi-disciplinary approach to address two objectives: (1) dissecting the regulatory mechanism underlying the processive motility of OsKCH2 using in vitro single-molecule imaging, and (2) interrogating the in vivo functions of OsKCH2 in cell division and plant growth by examining phenotypes linked to a null kch2 mutation.