NADPH oxidase‐dependent H₂O₂ production mediates salicylic acid‐induced salt tolerance in mangrove plant Kandelia obovata by regulating Na⁺/K⁺ and redox homeostasis

Abstract

SUMMARYSalicylic acid (SA) is known to enhance salt tolerance in plants. However, the mechanism of SA‐mediated response to high salinity in halophyte remains unclear. Using electrophysiological and molecular biological methods, we investigated the role of SA in response to high salinity in mangrove species, Kandelia obovata, a typical halophyte. Exposure of K. obovata roots to high salinity resulted in a rapid increase in endogenous SA produced by phenylalanine ammonia lyase pathway. The application of exogenous SA improved the salt tolerance of K. obovata, which depended on the NADPH oxidase‐mediated H2O2. Exogenous SA and H2O2 increased Na+ efflux and reduced K+ loss by regulating the transcription levels of Na+ and K+ transport‐related genes, thus reducing the Na+/K+ ratio in the salt‐treated K. obovata roots. In addition, exogenous SA‐enhanced antioxidant enzyme activity and its transcripts, and the expressions of four genes related to AsA‐GSH cycle as well, then alleviated oxidative damages in the salt‐treated K. obovata roots. However, the above effects of SA could be reversed by diphenyleneiodonium chloride (the NADPH oxidase inhibitor) and paclobutrazol (a SA biosynthesis inhibitor). Collectively, our results demonstrated that SA‐induced salt tolerance of K. obovata depends on NADPH oxidase‐generated H2O2 that affects Na+/K+ and redox homeostasis in response to high salinity.

Melatonin induces proline, secondary metabolites, sugars and antioxidants activity to regulate oxidative stress and ROS scavenging in salt stressed sword lily

“…Moreover, the countereffect of foliar treatment with exogenous MT at different concentrations to relieve SS was analysed. These results are supported by previous research indicating that excessive salt stress causes the formation of ROS, which affects carbon metabolism and the buildup of NADPH oxidase [ 66 , 67 ]. Lipid peroxidation is widely used as a marker of membrane integrity and its measurement can be used to determine malondialdehyde (MDA).…”

Modulation of Photosystem II Function in Celery via Foliar-Applied Salicylic Acid during Gradual Water Deficit Stress

“…Salicylic acid (SA) is considered an important phytohormone, being essential for controlling a broad array of biochemical and physiological processes that are involved in many stages of growth and development, including seed germination, flowering, regulation of ripening, and plant defense responses to pathogens and abiotic stimuli [11][12][13][14][15][16][17][18]. It has been suggested to have evident potential for mitigating numerous abiotic stresses of major agricultural crops, for improving their stress resistance, acting as an antioxidant, osmoregulator, and biostimulant [17,[19][20][21].…”