Nitrosative stress-mediated inhibition of gene expression suggests roots growth reduction in rice ( L.).

This study monitored the transcriptional response of under nitrosative stress conditions relative to the transcripts accumulations for the core mitochondrial cytochrome c oxidase1 () subunit, nuclear CcOX subunits and , two rice nitrate reductases ( and ), and nitric oxide excess 1 () genes. Our findings reveal that short-term exposure of rice seedlings to 1 mM SNP (Nitric oxide donor) applied exogenously for 1 h resulted in significant down-regulation of expression in all rice cultivars. In addition, the transcriptional patterns for the CcOX subunits, which are known to have a high affinity for nitric oxide, showed that the core catalytic subunit () and the nuclear subunit () were up-regulated, while the nuclear subunit () gene expression was suppressed expression was enhanced or decreased concomitant with a decrease or increase in SNO accumulation, particularly at the basal level. Moreover, high expression was consistent with impaired root development, whereas low transcript accumulation matched a balanced root-growth pattern. This suggests that expression would prevail over expression under nitrosative stress response in rice. The level of malondialdehyde (MDA) content increased with the increase in SNP concentration, translating enhanced oxidative damage to the cell. We also observed increased catalase activity in response to 5 mM SNP suggesting that potential cross-talk exist between nitrosative and oxidative stress. These results collectively suggest a possible role of and role in plant root growth during nitrosative stress responses.