Poster: Root Biology

Abs # 529: Glutathione positively regulates root hair formation in Arabidopsis thaliana

Presenter:	Nozomi, Kuroda , nkuroda@bio-ribs.com
Authors	Nozomi, Kuroda  (A)   Masaki, Iwabuchi  (A)   Ken'ichi, Ogawa  (A) (B)
Affiliations:	(A): Research Institute for Biological Sciences, Okayama (RIBS, Okayama) (B): Crest, JST

In plants, generation of reactive oxygen species (ROS) follows environmental stress such as strong light, high/low temperatures and drought, leading to cellular damages. However, plants have developed a defense system against oxdative stress. Glutathione (GSH) is a component of the defense system, synthesized mainly by photosynthesis. We have recently showed that GSH is involved in several physiological and developmental regulations (Ogawa et al., 2001; Henmi et al., 2001) as well as detoxication of ROS. However, the target molecules of GSH in the redox control remains to be elucidated. To address where GSH acts and which physiological events are under control of GSH, we first observed localization of GSH in Arabidopsis. The wild type plant showed a specific pattern of GSH accumulation in roots, especially in root apices and hairs. To address whether this pattern is associated with GSH function, GSH was applied to the plant, resulting in an increase in the number of root hairs. These suggest that GSH acts positively in root hair formation. Investigating several mutants having an aberration of root hair formation revealed an association of the pattern with the root hair forming position, leading to a finding of the mutant that lacked the root hair forming response to GSH but still had the specific pattern similar to the wild type. This mutant proved defective in the positive regulator CAPRICE (CPC) of root hair formation. Overexpression of CPC disrupted the pattern of GSH accumulation. With reference to effects of GSH on root formation, the cpc mutant was more sensitive to GSH than the wild type, while the CPC overexpressor was less. These all suggest that GSH acts on CPC to regulate root hair formation.