Hydrogen peroxide and nitric oxide mediate K+/Na+ homeostasis and antioxidant defense in NaCl-stressed callus cells of two contrasting poplars

Abstract

Using callus cells of a salt-tolerant Populus euphratica Oliver and a salt-sensitive P. popularis 35-44 (P. popularis), the effects of NaCl stress on hydrogen peroxide (H 2 O 2 ) and nitric oxide (NO) production and the relevance to ionic homeostasis and antioxidant defense were investigated. Results show that P. euphratica exhibited a greater capacity to tolerate NaCl stress in terms of cell viability, membrane permeability and K ? /Na ? relations. NaCl salinity (150 mM) caused a rapid increase of H 2 O 2 and NO in P. euphratica cells, but not in P. popularis. Moreover, salinised P. euphratica cells retained a high and stable level of H 2 O 2 and NO during the period of 24-h salt stress. Noteworthy, P. eupratica cells increased activities of superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase under salinity stress, but these antioxidant enzymes were significantly inhibited by the salt treatment in P. popularis cells. Pharmacological experiments proved that the NaCl-induced H 2 O 2 and NO was interdependent and contributed to the mediation of K ? /Na ? homeostasis and antioxidant defense in P. euphratica cells. Given these results, we conclude that the increased H 2 O 2 and NO enable P. euphratica cells to regulate ionic and ROS (reactive oxygen species) homeostasis under salinity stress in the longer term.

Role of Nitric Oxide in Salt Stress-induced Programmed Cell Death and Defense Mechanisms

“…A similar tendency was observed in Arabidopsis thaliana calli ) and Solatium lycopersicum cell suspension culture (Poor et al 2013). Rapid NO and ROS productions were detected in calli of a highly resistant species, Populus euphratica during salt stress (Sun et al 2010). These results suggested that the NaCl-induced NO production was: transient and NO levels increased significantly in parallel with ROS production in the first minutes and hours of salt treatment.…”

“…NO was visualized using 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA). White bars represent 1 mm (Poor et al unpublished et al 2008;Wang et al 2009;Sun et al 2010;Yang et al 2010), cell suspension cultures (Banu et al 2010;Poor andTari 2011), andprotoplasts (Gemes et al 2011) after NaCl treatment. Zhang et al (2006) observed time-dependent changes in NO production in Zea mays leaves after treatment with 100 mM NaCl.…”

“…NO donors decreased the salt-induced ROS production and activated SOD, peroxidases such as APX and GPX, CAT, and GR in various plant species. SNP promoted SOD-, POD-, and APX activities in Brassica juncea (Zeng et al 2011;Khan et al 2012), Populus euphratica (Sun et al 2010), and Cicer arietinum. plants (Sheokand et al 2010).…”

“…NO and ROS productions exhibited only small changes in salt-sensitive Populus popularis, therefore the cells displayed low K+/Na+ ratio and cell viability (Sun et al 2010). Zhao et al (2007a, b) demonstrated that a NOS inhibitor or a NO scavenger reduced endogenous NO levels and enhanced NaCl-induced decrease in K + /Na + ratio in Arabidopsis.…”

Identification and characterisation of candidate genes involved in chilling responses in maize (Zea mays L.)

“…/Na ? homeostasis and the metabolism of osmo-protective compounds (Sun et al 2010), the regulation of anion transporters and particularly of Cl -transport systems in chillingtreated plants have not been well understood yet. Voltagegated chloride channels of the CLC-type family are found in prokaryotic and eukaryotic organisms ranging from bacteria to animals and plants and mediate passive Cl -transport that is driven by the electrochemical gradient.…”