The Endophyte M2RT4 Induces the Systemic Release of Methyl Salicylate and ()-jasmone in Tomato Plant Affecting Host Location and Herbivory of .

The use of endophytic fungi has dramatically increased plant performance through the enhancement of plant protection against abiotic and biotic stressors. We previously demonstrated that the endophytic fungus M2RT4 improves tomato defenses against the tomato leafminer through the reduction of oviposition, leafmining, pupation, and adult emergence. However, the underlying mechanism by which the presence of this endophytic fungus within tomato host plant affects host selection and life-history traits is unknown. We tested the behavioral responses of in Y-tube olfactometer bioassays and found that females preferred non-inoculated tomato plants against those inoculated by endophytes. Additionally, females were not attracted to non-inoculated infested nor to inoculated-infested tomato plants. Chemical analysis revealed the emission of methyl salicylate in inoculated tomato plant and an increase in the amounts of monoterpenes emitted from non-inoculated infested plants. Additionally, we found that upon herbivory, M2RT4 modulates tomato plant chemistry through the production of ()-jasmone thus activating both salicylic and jasmonic acid defense pathways. Further, females were attracted to monoterpernes including α-pinene, 2-carene, and β-phellandrene but repelled by methyl salicylate. Methyl salicylate could therefore be considered as a good semiochemical-based candidate for sustainable management using a "push-pull" approach. However, in dose-response bioassays, females of did not show any preference to the four component-blend (α-pinene, 2-carene, β-phellandrene, and methyl salicylate). ()-jasmone-treated tomato leaflets significantly reduced the leafmining activity of the pest at the concentration of 10 ng/μL and causing the highest larval mortality rate (83%) with the shortest LT (1.73 days) 7 days post-treatment. M2RT4 effect on herbivore performance was then ()-jasmone-mediated. These findings expand our understanding of how the endophytic fungus M2RT4 could mediate chemical interactions between and its host plant which are potentially important for development of environmentally friendly management programs.