Abstract
Arabidopsis stm1 mutant, that is deficient in an ankyrin repeat protein, has a salt-tolerant phenotype (Sakamoto et al.,2006, PCP 47:suppl, P267). In this study, we analyzed this mutant with respect to its cellular responses to salt stress. Under salt stress conditions, the content of proline, one of osmoprotectants, increased to a similar extent in both the stm1 and wild-type plants (WT). In addition, the content of monovalent cations in the stm1 mutant was equivalent to that in the WT. It is known that salt stress causes overaccumulation of reactive oxygen species (ROS), which results in severe damages to plant cells. In the stm1 mutant, salt-induced ROS accumulation was markedly alleviated as compared with the WT, while no significant alteration was found in the regulation of osmotic and ionic balance. These results suggest a critical involvement of STM1 gene product in the regulation of ROS level in response to salt stress.
