Post-transcriptional regulation of AtMSD1 and expressions of AtMTM1, AtMTM2, and AtMSD1 under a shock of oxidative stress
To check the regulation of AtMSD1 in response to oxidative stress, we treated 2-week-old seedlings with 0.1 to 10 μM MV for a shock of 12 or 24 h oxidative stress and examined MnSOD activity. We also compared AtMTM1 , AtMTM2 , and AtMSD1 gene expression profiles under MV stress (Figure 5) .
The MnSOD activity in WT increased gradually with the increased dose of MV for 24 h by in-gel activity assay (Figure 5A, top) , but MnSOD protein level remained similar by immunoblotting (Figure 5A, bottom) , reflecting the phenomena of post-transcriptional regulation of MnSOD activity.
Specially, we observed the earlier and higher expression forAtMTM2 than AtMTM1 in response to 5 μM MV for 12 h treatment by qPCR (Figure 5B, top) . AtMSD1 and mitochondria oxidative stress-responsive maker gene AtAOX1A were up-regulated (Figure 5B, bottom) . Cytoplasmic oxidation-responsive marker genes AtAPX1 and AtCAT1 were used as references, and they also responded to MV stress at the early stage (Supplemental Figure S7) . Overall, the post-transcriptional MnSOD activity in WT under MV stress corresponded with the up-regulated AtMTM1 , AtMTM2 , and AtMSD1genes.