Diversity and effectiveness of arbuscular mycorrhizal fungi species in alleviating drought stress in tomato

Water scarcity poses significant challenges to sustainable agriculture, and the anticipated increase in the frequency and severity of droughts due to climate change intensifies these constraints. Therefore, there is an urgent need to identify eco-friendly approaches to enhance drought tolerance, especially in arid regions, to ensure global food security, considering the growing world population. This study investigated the morphological diversity of Arbuscular Mycorrhizal Fungi (AMF) species associated with the rhizosphere of cultivated tomato (Solanum lycopersicum L.) plants across diverse agroecosystems in twenty locations in Egypt. The results reveal the presence of five AMF species from the genus Glomus: G. invarmaium, G. xanthium, G. intraradices, G. mosseae, and G. macrocarpum. The study further explored the impact of mixed inoculation with the identified G. species on the physiological and morphological performance of tomato plants exposed to drought stress. The results showed that AMF inoculation significantly improved root colonization under drought stress. Inoculated plants showed significantly higher shoot and root fresh and dry weights than non-inoculated controls. AMF-inoculated plants also exhibited higher leaf chlorophyll concentrations and increased accumulation of stress-related metabolites such as proline, total soluble sugars, and glycine betaine compared to non-inoculated plants under drought stress. Leaf phosphorus concentration was enhanced in inoculated plants, whereas lipid peroxidation, indicated by malondialdehyde (MDA) levels, was reduced. Thermal imaging revealed that AMF inoculation led to lower canopy temperatures, indicating better stress tolerance. Therefore, AMF inoculation, particularly Glomus species, mitigated the adverse effects of drought stress on tomato plants, which indicates its potential for improving crop performance under water-limited conditions. These findings documented the importance of AMF in enhancing drought tolerance in tomato plants, suggesting that their application could be a viable strategy for sustainable agricultural practices in arid regions.