第1061回生物科学セミナー
Precise organ size arises from variable cellular growth in Arabidopsis
Ardienne Roeder（Cornell University）
2015年12月15日(火) 13：15-15：00 理学部2号館 201号室
Organ sizes are strikingly precise, despite the stochastic growth and division of individual cells within them. To reveal what mechanisms enable this precision, we screened for Arabidopsis mutants with variably sized sepal organs and identified mutations in the mitochondrial i-AAA protease FtsH4. Through live imaging, we observed substantially variable cell growth in both wild type and ftsh4 sepals. Through computational modeling and quantitative phenotypic analysis, we found that regular organ size results from spatiotemporal averaging of the cellular variability in wild type sepals, whereas in ftsh4 mutants the averaging process is disrupted. Reactive oxygen species (ROS) accumulated in ftsh4 mutants, abnormally increasing both cell wall stiffness and organ size variability. ROS also accumulated in the maturing cells of wild type sepals, and lowering ROS enzymatically produced larger sepals. Our results demonstrate an inverse relationship between the robustness of plant organ size and ROS, which we show is a key regulator terminating organogenesis.
