Abstract
We have reported that the T-DNA insertion to an H2O2-inducible glutathione S-transferase (GST) gene reduced gravisensing in the A. thaliana gravitropic response [Shiomi et al. (2004) PCP suppl. s45]. T-DNA insertion to an auxin-inducible gene of GST, which is known as an auxin-binding protein, resulted in the same tendency, suggesting that gravitropism involves the above two GST genes. To examine whether GSH, as a GST substrate, participates in the gravity response, these T-DNA inserted plants were treated to increase their endogenous GSH. In the T-DNA inserted plants, the root elongation for gravity direction was perturbed, while it was little affected in wild-type plants. Wild-type plants grown on media containing GSH reduced the gravity response in a dose-dependent manner. In contrast to wild-type plants, the T-DNA inserted plants recovered their gravity response. Taken together, it is suggested a gravity response system involving GST and GSH exists in the root.
