The glutathione-dependent alarm triggers signalling responses involved in plant acclimation to cadmium

Abstract

Cadmium (Cd) uptake from polluted soils inhibits plant growth and disturbs physiological processes, at least partly due to disturbances in the cellular redox environment. Although the sulfur-containing antioxidant glutathione is important in maintaining redox homeostasis, its role as an antioxidant can be overruled by its involvement in Cd chelation as a phytochelatin precursor. Following Cd exposure, plants rapidly invest in phytochelatin production, thereby disturbing the redox environment by transiently depleting glutathione concentrations. Consequently, a network of signalling responses is initiated, in which the phytohormone ethylene is an important player involved in the recovery of glutathione levels. Furthermore, these responses are intricately connected to organellar stress signalling and autophagy and contribute to cell fate determination. In general, this may pave the way for acclimation (e.g. restoration of glutathione levels and organellar homeostasis) and plant tolerance in case of mild stress conditions. This review addresses connections between these players and discusses the possible involvement of the gasotransmitter hydrogen sulfide in plant acclimation to Cd exposure.

Sulfur metabolism: actions for plant resilience and environmental adaptation

“…These toxic metals and metalloids are detrimental to plant health and thus may impact general cellular and organellar responses. Iven et al (2023) extend discussion on how GSH and PC pools alter in the event of plant exposure to Cd and influence the ethylene and reactive oxygen species (ROS)-mediated signaling networks. Ramification of stresses imposed by Cd appears to involve ethylene and ROS signaling communicating with mitochondrial retrograde signaling, unfolded protein response, and autophagy.…”

“…S 2– and OAS can also modulate the activity of the target of rapamycin (TOR) complex which optimizes plant growth ( Dong et al , 2017 ). Glutathione (γ-glutamylcysteinylglycine; GSH), the tripeptide synthesized from Cys, and Fe–S clusters impact the redox status ( Caubrière et al , 2023 ; Ito and Ohkama-Ohtsu, 2023 ; Iven et al , 2023 ; Pedroletti et al , 2023 ). Sulfation of metabolites and peptides generates 3’-phosphoadenosine-5’-phosphate (PAP), a retrograde signaling molecule communicating messages relevant to a wide spectrum of abiotic stress factors (e.g.…”

Sulfate Availability and Hormonal Signaling in the Coordination of Plant Growth and Development

“…After exposure to cadmium, plants quickly allocate resources to produce phytochelatins, which are oligomers of GSH, leading to the disruption of the redox environment by temporarily reducing GSH concentrations. As a result, a cascade of signaling responses is triggered, with ET playing a crucial role in restoring GSH levels [84]. It was recently shown that there is crosstalk between glucosinolate levels and the expression of ET-related genes under S deprivation [85].…”