The specification and maintenance of growth sites are tightly regulated during cell morphogenesis in all organisms. ROOT HAIR DEFECTIVE 2 reduced nicotinamide adenine dinucleotide phosphate (RHD2 NADPH) oxidase–derived reactive oxygen species (ROS) stimulate a Ca2+ influx into the cytoplasm that is required for root hair growth in Arabidopsis thaliana. We found that Ca2+, in turn, activated the RHD2 NADPH oxidase to produce ROS at the growing point in the root hair. Together, these components could establish a means of positive feedback regulation that maintains an active growth site in expanding root hair cells. Because the location and stability of growth sites predict the ultimate form of a plant cell, our findings demonstrate how a positive feedback mechanism involving RHD2, ROS, and Ca2+ can determine cell shape.
1 Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK.
2 Genome and Drug Research Center, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
3 Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
