Functional Analysis of Rice Glutaredoxin in Oxdative Stress Defense

Abstract

Glutaredoxin catalyzes the reduction of protein disulfide using the reducing power of glutathione and is supposed to participate in the defense against oxidative stress. However, its physiological role in higher plants is largely unknown. We previously found that rice glutaredoxin protein is abundantly expressed in developing and mature seeds, but not in seedlings or leaves. In this study, we investigated the antioxidant function of glutaredoxin from rice using yeast expression system and transgenic rice plants. Yeast cell lines expressing rice glutaredoxin showed increased tolerance against menadione but not against hydrogen peroxide compared with control. In contrast, expression of glutaredoxin decreased the paraquat tolerance and glutathione reductase activity in green leaves in transgenic rice plants. This result suggests that ectopically expressed glutaredoxin in green leaves might cause the perturbation of cellular redox balance which resulted in the decreased tolerance to oxidative stress.