Root hair tip growth regulation by Arabidopsis RHD2 and ROP-GTPase genes (HAIRY)

Lead Research Organisation: John Innes Centre
Department Name: Contracts Office

Abstract

Plant cells have two kinds of cell elongation systems; diffuse growth and tip growth. Tip growth is highly polarized and the growth only occurs at the tip of the cell. Root hairs are tip growing projections that arise from specialised root epidermal cells. The localization of growth to the hair tip is controlled by the local production of reactive oxygen species (ROS) produced by the RHD2 NADPH oxidase. Therefore identifying and characterising proteins that spatially regulate RHD2 activity is central to understand the mechanism of tip growth. However, how and where RHD2 protein is activated and regulates the accumulation of ROS at the root hair tip is still unknown. Thus, the aims of this research are to determine the subcellular localization of RHD2 proteins and determine if RHD2 is directly regulated by small Rho GTPases called ROPs, which I predict regulate this NADPH oxidase. Firstly I will determine subcellular localization of RHD2 protein in root hair cells. I will use plants expressing an RHD2-YFP fusion protein in combination with confocal microscopy and spinning disc microscopy to investigate the protein localization during hair development. Secondly, I will identify and characterize the ROPs that are expressed during root hair development. After identification of root hair specific ROP by whole mount in situ hybridization, I will determine the subcellular localization of ROP using plants expressing ROP and CFP fusion protein. Thirdly, I will test if RHD2 physically interacts with ROP proteins. Because RHD2 is predicted to be a membrane protein, I will use split-ubiquitin yeast two hybrid system to determine if RHD2 and ROP interact in vitro. For in vivo analysis, I will perform bimolecular fluorescence complementation (BiFC) and FRET approaches, both of which enable us to see the protein-protein interaction in developing root hairs. Together these analyses will define the mechanism of the RHD2 NADPH oxidase regulation during cell development.

Publications

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Carol RJ (2006) The role of reactive oxygen species in cell growth: lessons from root hairs. in Journal of experimental botany

 
Description This project discovered the role of the ROP GDI protein called SCN, previously called HAIRY, in the control of root hair growth.
Exploitation Route No foreseen use to non-academic advisors. It is unlikely that information from his project will have impact outside the academic field. This has been discussed with technology transfer companies including Plant Biosciences Ltd.