Trihoderma citrinoviride protects plants from diseases by functioning as antagonists of many pathogenic fungi or by triggering the antioxidant defense system in plants. In the present study, to uncover the possible alleviative role of Trichoderma against salinity and Rhizoctonia solani infection, strawberry plants were pretreated Trichoderma citrinoviride and then subjected to salinity, R. solani and combined salinity and R. solani. The effect of T. citrinoviride on the alleviation of the effects of salt stress and Rhizoctonia solani infection was investigated by analysing leaf dry weight, PSII efficiency, and the activity of some antioxidant enzymes in the leaves of strawberry plants. T. citrinoviride improved competitive capability against salinity and R. solani infection. It showed 79% inhibition of the growth of pathogen R. solani. T. citrinoviride reduced 63% of the severity of disease in the leaves. Trichoderma pretreatment maximized plant dry weight. The T. citrinoviride-pretreated plants showed higher levels of PSII efficiency (Fv/Fm). Decreased lipid peroxidation and H₂O₂ accumulation compared to untreated seedlings under salt stress and R. solani infection was observed. Trichoderma-pretreated and –untreated plants respond differently to salt stress and R. solani infection by means of antioxidant defense. As compared to untreated seedlings, treated seedlings showed significantly lower activities of antioxidant enzymes, superoxide dismutase (SOD), peroxidase (POX), cell wall peroxidase (CWPOX) under salt stress and R. solani infection, indicating that treated seedlings might sense lower stress as compared to untreated seedlings. The study reports the effective adaptive strategy and potential of T. citrinoviride in alleviating the negative impact of salt stress and R. solani infection in strawberry.

Plant glutamate receptor-like channels (GLRs) play important roles in plant development, immune response, defense signaling and Nitric oxide (NO) production. However, their involvement in abiotic stress responses, particularly in regulating Reactive Oxygen Species (ROS), is not well understood. This study aimed to investigate GLR-mediated NO production on ROS regulation in salt-stressed cells. To achieve this, Arabidopsis thaliana Columbia (Col-0) were treated with NaCl, glutamate antagonists [(DNQX (6,7-dinitroquinoxaline-2,3-dione and AP-5(D-2-amino-5-phosphono pentanoic acid)], and NO scavenger [cPTIO (2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt)]. Salt-stressed plants in combination with DNQX and AP-5 have exhibited higher increase in lipid peroxidation (TBARS), hydrogen peroxide (H₂O₂) and superoxide radical (O⁻²) contents as compared to solely NaCl-treated plants. Furthermore, NO and total glutathione contents, and S-nitrosoglutathione reductase (GSNOR) activity decreased with these treatments. AP-5 and DNQX increased the activities of NADPH oxidase (NOX), catalase (CAT), peroxidase (POX), cell wall peroxidase (CWPOX) in salt-stressed Arabidopsis leaves. However, their activities (except NOX) were significantly inhibited by cPTIO. Conversely, the combination of NaCl and GLR antagonists, NO scavenger decreased the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) resulting in elevated GSSG levels, a low GSH/GSSG ratio, impaired ROS scavenging, excessive ROS accumulation and cell membrane damage. The findings of this study provide evidence that GLR-mediated NO plays a crucial role in improvement of the tolerance of Arabidopsis plants to salt-induced oxidative stress. It helps to maintain cellular redox homeostasis by reducing ROS accumulation and increasing the activity of SOD, GSNOR, and the ASC-GSH cycle enzymes.

The aim of the present study was to determine the antioxidant system responses of a xerophytic plant to salinity and drought, which were not elucidated before. Physiological and antioxidant responses of the xerophytic plant Gypsophila aucheri Boiss. were investigated under salinity (100 and 300 mM NaCl) and drought (withholding watering) treatment for 2 weeks in a controlled growth chamber. Besides growth responses (relative growth rate (RGR)), superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), and glutathione reductase (GR) activities, and SOD and CAT isoenzymes activities were determined under stress conditions. Moreover, the level of lipid peroxidation was determined as thiobarbutiric acid reactive substances (TBARS) content. Tolerance of G. aucheri to salinity and drought was evaluated based on lipid peroxidation (oxidative damage) and RGR. According to the experiments, G. aucheri was found to be tolerant to drought and 100 mM NaCl and its antioxidant system was able to cope with oxidative stress under these conditions. However, 300 mM NaCl treatment had detrimental effects on plant growth and membrane integrity. Under this concentration, oxidative stress cannot be precluded in spite of increased SOD, POX, and APX activities. These data indicate that xerophytic G. aucheri is a moderate halophytic plant that uses an efficient antioxidant defence mechanism under salinity.

Carnitine, a ubiquitous compound in living organisms, fulfills diverse roles in energy metabolism, stress resilience, and detoxification. Its antioxidant and osmolyte traits offer relief to stressed plants. Antagonizing abscisic acid (ABA), carnitine influences ABA-responsive genes. Our study, using Arabidopsis thaliana wild-type Ler. (Landsberg erecta) and ABA-insensitive abi2-1 mutants, explored carnitine’s impact on antioxidative responses and ABI2’s role in salt-induced carnitine metabolism. The application of 5 µM carnitine has alleviated the decrease in RWC, shoot weight, and rosette diameter WT plants caused by 80 mM salt stress for 4 days. Carnitine reduced cell membrane damage and salinity effects, evidenced by decreased lipid peroxidation and H₂O₂. In contrast, the impaired ABI2 of abi2-1, due to deficient phosphatase activity, further exacerbated the inhibitory effect of carnitine on the enzymes of the ascorbate-glutathione cycle, consequently reducing stress mitigation. While abi2-1 mutants exhibited unchanged superoxide dismutase (SOD) activity, they demonstrated increased catalase and peroxidase activity following carnitine treatment under salt stress compared to WT plants. Conversely, wild-type WT plants treated with carnitine exhibited elevated total glutathione content under salt stress, a response not observed in abi2-1 mutants under carnitine treatment. These results underscore the crucial role of ABI2-dependent ABA signaling in regulating plant carnitine metabolism.