Determination of hydrogen peroxide (H2O2) priming on antioxidant enzyme activities and gene expression levels i̇n tomato (Solanum lycopersicum) seedlings exposed to salt stress

Due to their silent structure, plants respond to the stress factors caused by abiotic and biotic stresses occurring in their environment through their antioxidant systems. Salinity and alkalinity are the most important abiotic stress factors for plants. Plants try to respond to stresses by activating various signalling pathways to increase their tolerance to these stresses. A wide variety of pesticides such as pesticides and herbicides are used to protect the plants cultivated in agricultural lands from biotic agents. However, there is no known common practice to strengthen the defence mechanism against abiotic stresses. In this study, the effect of H2O2 pretreatment on the alleviation of salt stress in tomato seedlings was investigated. In this context, 4 different experimental groups were formed (control, H2O2, Salt, Salt+H2O2) and the changes in chlorophyll content, MDA accumulation, SOD, CAT, APX enzyme activities and expression were examined. As a result of the study, an increase in the amount of chlorophyll and a decrease in MDA accumulation occurred after the priming treatment compared to the salt stress alone group. In addition, the activation of stress-related enzymes was significantly higher than the salt stress only group. Expression levels showed a statistically significant increase compared to the control, but CAT and APX expression levels were found to be lower than the salt stress only group. As a result, H2O2 priming application was found to help increase the stress tolerance of the plant. The priming method can be used as a highly functional tool to alleviate the stress effect for plants, but the type, concentration and exposure time of the priming agent were found to be very important factors for regulating the effect of priming.