NADPH oxidase AtrbohD and AtrbohF function in ROS-dependent regulation of Na+/K+ homeostasis in Arabidopsis under salt stress

Abstract

Maintaining cellular Na(+)/K(+) homeostasis is pivotal for plant survival in saline environments. However, knowledge about the molecular regulatory mechanisms of Na(+)/K(+) homeostasis in plants under salt stress is largely lacking. In this report, the Arabidopsis double mutants atrbohD1/F1 and atrbohD2/F2, in which the AtrbohD and AtrbohF genes are disrupted and generation of reactive oxygen species (ROS) is pronouncedly inhibited, were found to be much more sensitive to NaCl treatments than wild-type (WT) and the single null mutant atrbohD1 and atrbohF1 plants. Furthermore, the two double mutant seedlings had significantly higher Na(+) contents, lower K(+) contents, and resultant greater Na(+)/K(+) ratios than the WT, atrbohD1, and atrbohF1 under salt stress. Exogenous H(2)O(2) can partially reverse the increased effects of NaCl on Na(+)/K(+) ratios in the double mutant plants. Pre-treatments with diphenylene iodonium chloride, a widely used inhibitor of NADPH oxidase, clearly enhanced the Na(+)/K(+) ratios in WT seedlings under salt stress. Moreover, NaCl-inhibited inward K(+) currents were arrested, and NaCl-promoted increases in cytosolic Ca(2+) and plasma membrane Ca(2+) influx currents were markedly attenuated in atrbohD1/F1 plants. No significant differences in the sensitivity to osmotic or oxidative stress among the WT, atrbohD1, atrbohF1, atrbohD1/F1, and atrbohD2/F2 were observed. Taken together, these results strongly suggest that ROS produced by both AtrbohD and AtrbohF function as signal molecules to regulate Na(+)/K(+) homeostasis, thus improving the salt tolerance of Arabidopsis.

SALT-RESPONSIVE ERF1 Regulates Reactive Oxygen Species-Dependent Signaling during the Initial Response to Salt Stress in Rice

“…Recently, it has been demonstrated that ROS production by NADPH oxidases is crucial for mediating salt stress tolerance and that exogenous H 2 O 2 improves salinity tolerance in Arabidopsis (Ma et al, 2012). During the initial phase of salt stress, increased ROS levels might act as an acclimation signal.…”

“…Salt-induced ROS are predominantly represented by H 2 O 2 , both outside and inside the cell Pang and Wang, 2008). Extracellular ROS production depends on the activity of NADPH oxidases that contribute to salt stress tolerance in Arabidopsis thaliana (Ma et al, 2012). In rice (Oryza sativa), NADPH oxidase-dependent H 2 O 2 production emerges within several minutes of salt stress (Hong et al, 2009).…”

SNF1-Related Protein Kinases Type 2 Are Involved in Plant Responses to Cadmium Stress

“…Moreover, the kinase interacts with AtrbohF in bimolecular fluorescence complementation assay, suggesting that NADPH oxidase could be a SnRK2.6/OST1 substrate in vivo (Sirichandra et al, 2009). AtrbohF and AtrbohD (another NADPH oxidase), which are abundant in plant roots, are involved in ROS production in response to several abiotic and biotic stresses (Sagi and Fluhr, 2006;Suzuki et al, 2011;Ma et al, 2012;Marino et al, 2012). It was shown that phosphorylation and Ca 2+ binding are needed for AtrbohD and AtrbohF activation (Ogasawara et al, 2008;Kimura et al, 2012).…”

Clathrin and Membrane Microdomains Cooperatively Regulate RbohD Dynamics and Activity in Arabidopsis

“…The results showed that the mean protein proximity value increased to 0.42 6 0.09 (P < 0.01) and 0.35 6 0.04 (P < 0.05) (n = 10 cells) after ionomycin and calyculin A treatments, respectively, indicating that both Ca 2+ and phosphorylation enhanced mCherry-RbohD and GFP-Flot1 colocalization. RbohD plays a key role in the response to salt stress, and salt acclimation requires the ROS generated by RbohD (Xie et al, 2011;Ma et al, 2012). Therefore, we used FM4-64 to investigate the dynamics and endocytic pathways of GFP-RbohD under salt stress.…”