Resistance of tomato (Solanum Lycopersicum) to the fungal pathogen Botrytis cinerea requires complex interplay between hormonal signalling. In this study, we explored the involvement of new
oxylipins in the tomato basal and induced response to this necrotroph through the functional analysis of the tomato α-dioxygenase2 (α-DOX2)-deficient mutant divaricata. We also investigated the role of SA in the defence response against this necrotrophic fungus using SA-deficient tomato nahG plants. The plants lacking dioxigenase α-DOX2, which catalyses
oxylipins production from
fatty acids, were more susceptible to Botrytis, and
hexanoic acid-induced resistance (Hx-IR) was impaired; hence α-DOX2 is required for both tomato defence and the enhanced protection conferred by natural inducer
hexanoic acid (Hx) against B. cinerea. The divaricata plants accumulated less pathogen-induced
callose and presented lower levels of
jasmonic acid (JA) and
12-oxo-phytodienoic acid (
OPDA) upon
infection if compared to the wild type. Glutathion-S-
transferase (GST) gene expression decreased and ROS production significantly increased in Botrytis-infected divaricata plants. These results indicate that absence of α-DOX2 influences the hormonal changes, oxidative burst and
callose deposition that occur upon Botrytis
infection in tomato. The study of SA-deficient nahG tomato plants showed that the plants with low SA levels displayed increased resistance to Botrytis, but were unable to display Hx-IR. This supports the involvement of SA in Hx-IR. NaghG plants displayed reduced
callose and ROS accumulation upon
infection and an increased GST expression. This reflects a positive relationship between SA and these defensive mechanisms in tomato. Finally, Hx boosted the pathogen-induced
callose in nahG plants, suggesting that this priming mechanism is SA-independent. Our results support the involvement of the
oxylipins pathway and SA in tomato response to Botrytis, probably through complex crosstalk of the hormonal balance with
callose and ROS accumulation, and reinforce the role of the oxidative stress in the outcome of the plant-Botrytis interaction.