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.
