Journal
PLANT PHYSIOLOGY AND BIOCHEMISTRY
Volume 196, Issue -, Pages 841-849Publisher
ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
DOI: 10.1016/j.plaphy.2023.02.047
Keywords
Antioxidants; Cell death; Ethylene; Fusaric acid; Oxidative stress
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The study explored the time-dependent effects of FA concentrations on ROS regulation in tomato leaves. Both genotypes showed increased superoxide and H2O2 accumulation under FA exposure, with Nr genotype being more sensitive. Nr also exhibited higher lipid peroxidation and lower antioxidant enzyme activities compared to WT. ET was found to play a regulatory role in activating enzymatic and non-enzymatic antioxidants to detoxify excess ROS accumulation.
The mycotoxin fusaric acid (FA) induces rapid oxidative burst leading to cell death in plants. At the same time, plant defence reactions are mediated by several phytohormones for instance ethylene (ET). However, previously conducted studies leave research gaps on how ET plays a regulatory role under mycotoxin exposure. Therefore, this study aims to the time-dependent effects of two FA concentrations (0.1 mM and 1 mM) were explored on the regulation of reactive oxygen species (ROS) in leaves of wild-type (WT) and ET receptor mutant Never ripe (Nr) tomatoes. FA induced superoxide and H2O2 accumulation in both genotypes in a mycotoxin dose-and exposure time-dependent pattern. 1 mM FA activated NADPH oxidase (+34% compared to the control) and RBOH1 transcript levels in WT leaves. However, superoxide production was significantly higher in Nr with 62% which could contribute to higher lipid peroxidation in this genotype. In parallel, the antioxidative defence mechanisms were also activated. Both peroxidase and superoxide dismutase activities were lower in Nr but ascorbate peroxidase showed one-fold higher activity under 1 mM FA stress than in WT leaves. Interestingly, catalase (CAT) activity decreased upon FA in a time-and concentration-dependent manner and the encoding CAT genes were also downregulated, especially in Nr leaves at 20%. Ascorbate level was decreased and glutathione remained lower in Nr than WT plants under FA exposure. Conclusively, Nr genotype showed more sensitivity to FA-induced ROS suggesting that ET serves defence reactions of plants by activating several enzymatic and non-enzymatic antioxidants to detoxify excess ROS accumulation.
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