Ethylene and nitric oxide are involved in maintaining ion homeostasis in Arabidopsis callus under salt stress

Abstract

In the present study, the role of ethylene in nitric oxide (NO)-mediated protection by modulating ion homeostasis in Arabidopsis callus under salt stress was investigated. Results showed that the ethylene-insensitive mutant etr1-3 was more sensitive to salt stress than the wild type (WT). Under 100 mM NaCl, etr1-3 callus displayed a greater electrolyte leakage and Na(+)/K(+) ratio but a lower plasma membrane (PM) H(+)-ATPase activity compared to WT callus. Application of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC, an ethylene precursor) or sodium nitroprusside (SNP, a NO donor) alleviated NaCl-induced injury by maintaining a lower Na(+)/K(+) ratio and an increased PM H(+)-ATPase activity in WT callus but not in etr1-3 callus. The SNP actions in NaCl stress were attenuated by a specific NO scavenger or an ethylene biosynthesis inhibitor in WT callus. Under 100 mM NaCl, the NO accumulation and ethylene emission appeared at early time, and NO production greatly stimulated ethylene emission in WT callus. In addition, ethylene induced the expression of PM H(+)-ATPase genes under salt stress. The recovery experiment showed that NaCl-induced injury was reversible, as signaled by the similar recovery of Na(+)/K(+) ratio and PM H(+)-ATPase activity in WT callus. Taken together, the results indicate that ethylene and NO cooperate in stimulating PM H(+)-ATPase activity to modulate ion homeostasis for salt tolerance, and ethylene may be a part of the downstream signal molecular in NO action.

Cross Talk between Nitric Oxide and Phytohormones Regulate Plant Development during Abiotic Stresses

“…Studies involving tobacco seedlings showed that transcriptional activation of ethylene response factor (ERF) in ethylene-signaling process improved salt stress tolerance by decreasing ROS accumulation [89]. Treatment of Arabidopsis callus with 100 mM NaCl triggered the accumulation of NO that promoted ET emission, resulting in increased expression of the plasma membrane H + -ATPase genes [90]. Hence, both NO and ET participate in up-regulation of plasma membrane H + -ATPase that modulates ion homeostasis for improved salt tolerance.…”

Alterations of Endogenous Hormonal Levels in Plants under Drought and Salinity

“…Thus, under slight drought IAA level had no significant change, after moderate drought stress IAA level was reduced to about 81%, and after severe drought stress the level of this Aux was reduced to 72% of the control. The salinity stress induces an Aux accumulation in Arabidopsis and its redistribution to the root tip, resulting in the primary root growth inhibition, a marked reduction in lateral root primordia formation, and significantly increases in the elongation of existing lateral roots [71] (Figure 2). Thus, these results suggest that Aux transport appears to be essential for the adaptive remodeling of root system architecture under salinity.…”

Nitric oxide negatively regulates AKT1-mediated potassium uptake through modulating vitamin B6 homeostasis in Arabidopsis

“…NO production is altered when plants are subjected to abiotic or biotic stresses (13,14). High salt, a major environmental factor that limits agriculture yield, induces a quick endogenous NO accumulation in plants (15,16), and triggers enhanced Na + influx and reduced K + absorption in the root (17). Both endogenously produced NO and exogenously applied NO have been proposed to enhance plant salt tolerance (18-21) by attenuating high saltinduced increases in the Na + to K + ratio.…”