Controlled levels of salicylic acid are required for optimal photosynthesis and redox homeostasis

Abstract

Sudden exposure of plants to high light (HL) leads to metabolic and physiological disruption of the photosynthetic cells. Changes in ROS content, adjustment of photosynthetic processes and the antioxidant pools and, ultimately, gene induction are essential components for a successful acclimation to the new light conditions. The influence of salicylic acid (SA) on plant growth, short-term acclimation to HL, and on the redox homeostasis of Arabidopsis thaliana leaves was assessed here. The dwarf phenotype displayed by mutants with high SA content (cpr1-1, cpr5-1, cpr6-1, and dnd1-1) was less pronounced when these plants were grown in HL, suggesting that the inhibitory effect of SA on growth was partly overcome at higher light intensities. Moreover, higher SA content affected energy conversion processes in low light, but did not impair short-term acclimation to HL. On the other hand, mutants with low foliar SA content (NahG and sid2-2) were impaired in acclimation to transient exposure to HL and thus predisposed to oxidative stress. Low and high SA levels were strictly correlated to a lower and higher foliar H(2)O(2) content, respectively. Furthermore high SA was also associated with higher GSH contents, suggesting a tight correlation between SA, H(2)O(2) and GSH contents in plants. These observations implied an essential role of SA in the acclimation processes and in regulating the redox homeostasis of the cell. Implications for the role of SA in pathogen defence signalling are also discussed.

Synthesis and role of salicylic acid in wheat varieties with different levels of cadmium tolerance

“…These results are in agreement with earlier findings where SA treatment increased the reduced glutathione content and decreased that of the oxidized form, leading to an increased GSH/GSSG ratio in pea [35]. It was also reported that controlled levels of SA were required for optimal redox homeostasis [36]; furthermore, a relationship between SA and GR or GST was detected in the wheat x powdery mildew host x pathogen interaction [37]. The present results suggest that the increased SA level during Cd stress in the roots of Mv8 and Mv…”

Programmed cell death in the plant immune system

“…82 LSD1 protects plants from ROS-induced stresses and consequently, lsd1 mutant plants are characterized by runaway cell death (rcd). 79,83 Therefore, lsd1 can be regarded as a sensitized mutant with respect to cell death initiation, and it has been instrumental in identifying other components of the signaling pathway leading to programmed cell death. For example, EDS1 and PAD4 functions are required for lsd1 rcd induced by abiotic stress.…”

“…For example, EDS1 and PAD4 functions are required for lsd1 rcd induced by abiotic stress. 83 EDS1, PAD4 and NDR1 are also required for full lsd1 rcd in response to pathogen infection. 84 EDS1 and PAD4 regulate a ROS-and SA-dependent signal amplification loop, which in turn is modulated by LSD1.…”

Redox potential (Eh) and pH as drivers of soil/plant/microorganism systems: a transdisciplinary overview pointing to integrative opportunities for agronomy

“…A very widely-found local defense mechanism is the generation of ROS as a hypersensitive response of plants to pathogens and subsequent stress on the colonizing microbes or neighboring roots (Blokhina et al 2003;Bolwell et al 1995;Hartmann et al 2009;Lamb and Dixon 1997;Mori and Schroeder 2004). Increased disease resistance is very likely to be a combinatorial effect of redox signals triggered by salicylic acid, H 2 O 2 , glutathione, and potentially additional yet unidentified compounds (Mateo et al 2006). The ascorbate-glutathione (AsA-GSH) cycle serves as the main antioxidant pathway in plant cells, linking protection against ROS to redoxregulated plant defenses (Kuzniak 2010).…”