Exploring the role of tomato yellow leaf curl Sardinia virus infection and viral C4 protein in priming tomato plants against drought stress and powdery mildew infection

Abiotic and biotic stresses, such as drought and viral infections, can occur simultaneously in plants. It has been suggested that viruses can compensate host plants by assisting them to withstand stresses. This theory supports the presence of shared molecular networks governing the reaction of plants to stimuli induced by biotic and abiotic pressures. Begomoviruses have recently been proven to increase tolerance to heat and drought in Arabidopsis thaliana, possibly mediated by the C4 protein. We investigated how the infection of the begomovirus tomato yellow leaf curl Sardinia virus (TYLCSV) and the overexpression of its C4 protein regulate physiological and molecular processes in tomato plants subjected to drought stress. In addition, we also investigated if TYLCSV C4 could improve resistance to infections of Oidium neolycopersici, causing powdery mildew. We observed reduction of powdery mildew symptoms and changes in the expression of genes involved in pathogenesis and phytohormone production. Understanding how TYLCSV, its C4 protein, and the defence signalling pathways interact at the molecular level could help scientists create new approaches for priming plant resistance to different stresses. In conclusion, research on the function of TYLCSV and its C4 protein in protecting tomato plants from drought stress and fungal infection brings up new perspectives on the intricate relationships between viral pathogens and plant stress responses.