Free and Radical Control of Root Hairs

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Science's STKE  01 Apr 2003:
Vol. 2003, Issue 176, pp. tw128-TW128
DOI: 10.1126/stke.2003.176.tw128

Plant roots elongate and elaborate root hairs into surrounding soil to increase uptake of water and nutrients. This protruding process is rapid and requires calcium influx through channels at the cell surface to support requisite cell elongation. Foreman et al. have determined that the short-root-hair phenotype of an Arabidopsis thaliana mutant (rhd2) is caused by mutation of a gene that encodes a homolog of gp91phox, the mammalian NADPH oxidase cytochrome. This subunit is part of the respiratory burst oxidase that catalyzes reactive oxygen species (ROS) production. ROS accumulation was observed in elongating wild-type root hair tips, but not in those of the rhd2 mutant. Application of exogenous ROS to excised root apices stimulated cell growth and calcium influx in root hairs from the rhd2 mutant. These effects were blocked by pharmacological inhibitors of either the NADPH oxidase or calcium channels. The authors propose a developmental role for ROS in plants, and suggest that this ROS-activated calcium channel mechanism may operate in other cell types that undergo cell elongation.

J. Foreman, V. Demidchik, J. H. F. Bothwell, P. Mylona, H. Miedema, M. A. Torres, P. Linstead, S. Costa, C. Brownlee, J. D. G. Jones, J. M. Davies, L. Dolan, Reactive oxygen species produced by NADPH oxidase regulate plant cell growth. Nature 422, 442-446 (2003). [Online Journal]

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