Abstract
We have reported that plant development from seed germination to flowering is regulated by H2O2 in many plants. However, the molecular mechanism is not fully understood. Using rice and A.thaliana as model plants, we are trying to elucidate the molecular mechanism. The cDNA microarray and RT-PCR analysis of rice plants showed that the gene expression of one glutathione S-transferase (GST) changed by H2O2 treatment. Based on our previous finding that glutathione is also associated with plant growth, we focused on the physiological roles of this GST. Among GSTs is an auxin-binding protein. Then, to examine root gravitropism which involves auxin, we generated transgenic Arabidopsis overexpressing the rice GST and screened for two knocked-out Arabidopsis lines of auxin-inducible GST. The GST-overexpressing plants superfluously responded to gravity, and the knockout of one of the two GST genes reduced gravisensing. These suggest that gravisensing involves a specific GST.
