Production Of ROS In Sos2 Under Salt Stress And The Function Of AtMCA Gene

Under salt stress plant can produce and accumulate reactive oxygen species (ROS) that cause oxidative stress. ROS damage nucleic acid, protein and membrane. It's essential for plant to control ROS concentration within cell and repair the stress damage in time under stress.It has been reported that sos2 mutant shows sensitivity to salt due to reduced activity of Na+/H+ transporter. Whether ROS contributes equally to its salt sensitibity is unkown. We detected the content of H2O2 and O2-, by DAB and NBT staining respectively, in wild type and sos2 mutant leaves. DCFH-DA was used to detect ROS changes in roots. The results showed that sos2 mutant accumulated more ROS under salt stress. These evidence support the hypothesis hereinabove.Recent research indicates a member of AAA family, FtsH protease, which play key roles in plant. For example they assist protein to fold and degrade non-native peptide. The Arabidopsis contain three AAA metalloprotease, named FtsH3, FtsH4, FtsHIO respectively, whose exact function haven't been elucidated yet. We have cloned FtsH3 and named it "AtMCA ( Mitochondrial Cytochrome oxidase-related AAA-ATPases of Arabidopsis ) " before the name "FtsH3" was suggested.The AtMCA gene expression was inhibited in sos2 mutant under salt stress from the data of our lab. In this study , we found that the activity of cytochrome oxidase in sos2 was lower than wild type . AtMC4-overexpression in sos2 mutant resulted in enhanced activity of cytochrome oxidase. The transgenic plants showed higher salt tolerance than sos2. These results indicated mitochondrial AAA protease play key role under salt stess through increasing the activity of cytochrome oxiedse.