Alleviation of the adverse effects of drought stress using a desert adapted endophytic fungus and glucose in tomato

Abstract

Beneficial interaction of plants with fungi is one strategy for adapting to environmental stresses like drought. Serendipita indica, an endophytic root fungus, promotes plant growth and enhances tolerance to abiotic stresses. The present study aimed to investigate the amelioration of drought stress in tomato (Solanum lycopersicum L.) upon S. indica and glucose application through morpho-physiological analysis. A completely randomized design was applied with two types of fungal inoculation (non-inoculated and S. indica), two glucose concentrations (0 and 20 mM), and three levels of drought stress (0, 10%, and 20% polyethylene glycol) with three replications per treatment. The plants were collected to analyze various growth and physiological parameters 6 weeks after inoculation. The results showed that S. indica enhances root and shoot biomass and also root volume of inoculated plants in all treatments. An increase in carbohydrate (76%), proline (3.77-fold), potassium (21%), phosphorous (2.62-fold), antioxidant enzymes (peroxidase, ascorbate peroxidase, catalase and superoxide dismutase), total chlorophyll (33%), and carotenoid (16%) content were also observed with S. indica treated plants over untreated plants under drought stress. Additionally, the endophyte decreased hydrogen peroxide (H2O2), malondialdehyde (MDA), and electrolyte leakage (EL) by 20, 10 and 22%, respectively. The results showed that the level of carbohydrate (90%), proline (35%), potassium (7%), plant water status (3%), chlorophyll (11%) and carotenoid (6%), as well as the activities of antioxidant enzymes, were increased in glucose-treated plants. Moreover, glucose application decreases the levels of MDA, hydrogen peroxide (H2O2), and EL by 4, 7 and 13%, respectively. Overall, the interaction effect between fungal inoculation and glucose treatment with drought stress was significant in nearly all measured traits, which means both fungus and glucose promotes plant growth and can enhance drought stress tolerance. Hence, these indicate that S. indica and glucose co-application should be further investigated with field trials.