Grafting increases superoxide dismutase and catalase activity to overcome the impact of the two-spotted spider mite on eggplant growth and productivity

Abstract

Grafting vegetable crops is considered a valuable tool for improving the yield and quality of fruits under various stress conditions. This study aimed to assess the influence of grafting eggplant Solanum melongena (cv. A338) onto Solanum torvum rootstock (cv. STT3) on the incidence of the two-spotted spider mite Tetranychus urticae (TSSM). An experimental study was conducted to investigate the defense response elicited, as assessed by measuring the activities of antioxidant enzymes like superoxide dismutase (SOD) and catalase (CAT), as well as hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and chlorophyll contents in grafted and non-grafted eggplants under different TSSM infestation levels (10, 30 and 50 adults per plant). In addition, the effect of grafting on plant growth and yield of eggplant was evaluated. According to the findings of the present study, grafted plants had a lower density of TSSM than non-grafted plants. The number of eggs, nymphs, and adults on grafted plants was 40.11%, 31.71%, and 27.54%, respectively, lower than on non-grafted plants. With increasing TSSM density, the activities of CAT and SOD were increased at varying degrees. In terms of SOD activity, the grafted plants outperformed both the non-grafted scion and rootstock at all TSSM densities. In addition, the results demonstrated that plants with greater CAT activity were able to maintain a lower H<sub>2</sub>O<sub>2</sub> content and vice versa. The lower negative impacts on photosynthetic pigments demonstrated that grafted plants on S. torvum were more resistant to mite-induced damage to chlorophyll and carotenoids as mite density elevated. The grafted plants were superior in vegetative growth, and the total fruit weight was found to be two times higher than non-grafted plants. The features modified by grafting, such as the increased activities of SOD and CAT, can alleviate the impact of TSSM. Therefore, grafting could constitute a valuable tool when combined with other strategies of Integrated Pest Management (IPM) in the two-spotted spider mite control programs.