AtrbohD functions downstream of ROP2 and positively regulates waterlogging response in Arabidopsis.

NADPH oxidase AtrbohD plays very important roles in modulating many cellular processes through production of signal molecules reactive oxygen species in Arabidopsis. However, whether it regulates the response to waterlogging stress is unclear. In this report, we showed that expression of AtrbohD was markedly induced by waterlogging stress, and mutation in AtrbohD led to clear sensitivity of Arabidopsis plants to waterlogging stress. Moreover, waterlogging-promoted increases in alcohol dehydrogenase (ADH) activity, ADH1 expression and H2O2 accumulation were significantly attenuated in two mutant lines of AtrbohD. These results indicate that AtrbohD is required for Arabidopsis tolerance to waterlogging stress. Besides, GUS staining experiments revealed that disruption of small G protein ROP2 encoding gene evidently suppressed the increase of AtrbohD expression while defect of AtrbohD did not prominently affect the abundance enhancements of ROP2 transcripts under waterlogged conditions. Together, these data suggest that AtrbohD functions downstream of ROP2 to positively regulate the response to waterlogging stress in Arabidopsis.