Rootstock Increases The Physiological Defence Of Tomato Plants To Pseudomonas Syringae Pv. Tomato Infection.

Climate change has intensified tomato plant infection by pathogens such as Pseudomonas syringae pv. tomato (Pst). Rootstocks may increase plant tolerance to leaf phytopathogens. The aim of this study was to evaluate the effects of the tolerant Poncho Negro (R) tomato rootstock on the physiological defence and the role of H2S in susceptible Limachino (L) tomato plant responses to Pst attack. Ungrafted (L), self-grafted (L/L) and grafted (L/R) plants were infected with Pst. Rootstock increased the antioxidant compounds including ascorbate in the scion. Tolerant rootstock induced an increase of H2S in the scion of the plants, which correlated with an enhanced expression of the SlAPX2 gene. A high accumulation of salicylic acid was observed in both Pst inoculated grafted plants, but in higher levels in L/R plant. The increase of H2S during bacterial infection was associated with a reduction of ethylene in L/R plants. Our study indicated that the rootstock reduced the damage of the bacterial speck disease in the Limachino tomato plants, conferring tolerance to bacterial infection. This study provides new knowledge of the impact of rootstock in the defence of tomato plants to leaf pathogens for sustainable management of tomato cultivation.