Implication of the overexpression of PR genes and oxidative stress genes in the efficacy of natural substances against Oidium neolycopersici

Abstract: Powdery mildew, caused by the fungus Oidium neolycopersici, poses a significant
threat to tomato (Solanum lycopersicum L.) cultivation. In many cases, chemical products are used to control the disease, but they come with limitations such as negative effects on health and the environment, and the development of resistance to pathogens. Biocontrol, especially plant resistance inducers, appears to be a promising alternative to chemicals for protecting tomatoes against powdery mildew. The aim of this study is to evaluate the efficacy of natural substances against Oidium neolycopersici and to investigate their modes of action, using a transcriptomic approach. We analyzed the expression levels of 28 tomato defense genes in tomato plants treated with these substances. Our results demonstrated that the most effective natural substances against powdery mildew induce the overexpression of Pathogenesis-Related (PR) genes and oxidative stress genes. Our results also show variation in the expression levels of these genes according to the tomato genotype. These findings enrich our understanding of plant defense mechanisms induced by effective plant resistance inducers against powdery mildew, paving the way for innovative pest management approaches based on the development of tomato varieties that respond favorably to the application of plant resistance inducers.