Jasmonic acid and hydrogen sulfide modulate transcriptional and enzymatic changes of plasma membrane NADPH oxidases (NOXs) and decrease oxidative damage inOryza sativaL. during thiocyanate exposure

It is evident that the plasma membrane NADPH oxidases (NOXs) play an important role in the generation of superoxide radicals (O-2(-center dot)) in plants during defense responses. This study was to clarify activation of NOXs in oxidative damage inOryza sativaduring SCN(-)exposure, particularly in the roles of jasmonic acid (JA) and hydrogen sulfide (H2S) on transcriptional and enzymatic changes of NOXs. Results indicated that enzymatic activity of NOXs in both roots and shoots was significantly enhanced during SCN(-)exposure, whereas the application of JA and H2S donor (NaHS) significantly repressed NOXs activity in SCN-treated rice seedlings. Similarly, ROS analysis showed that SCN(-)exposure elevated the content of O-2(-center dot), hydrogen peroxide (H2O2) and malondialdehyde (MDA) in rice tissues significantly, whereas decreases in O(2)(-center dot)and H(2)O(2)were detected in roots and shoots of SCN-treated rice seedlings due to application of JA and NaHS. PCR analysis revealed different expression patterns of 7 plasma membrane-localized NOX genes in rice roots and shoots against SCN(-)exposure, suggesting that various isogenes of NOXs might regulate and determine activity of NOXs in rice organs. In conclusion, SCN(-)exposure was able to trigger activation of NOXs effectively, and led to oxidative damage and lipid peroxidation; the effects of JA and NaHS on inactivation of NOXs was evident and tissue specific, which in turn modulated ROS accumulation in rice plants.

Automated summary

This study showed that NOXs activity in rice was enhanced during SCN(-) exposure, but repressed by JA and NaHS. SCN(-) exposure increased the levels of reactive oxygen species significantly in rice tissues, but JA and NaHS application reduced these levels. The different expression patterns of NOX genes in rice roots and shoots suggested tissue-specific regulation and determination of NOX activity.