Induction of resistance to Botrytis cinerea by ethylene is evolutionary conserved but ethylene inhibits vanillylnonanamide induced resistance
Abstract: Ethylene is a plant hormone involved in resistance against pathogens, mainlynecrotrophs as Botrytis cinerea. In the present paper we demonstrate the ability of ethylene toinduce resistance against Botrytis cinerea and Phytophthora capsici in pepper. Jasmonic acid wasalso able to induce resistance against B. cinerea, but salicylic acid was not. In order to test if thisability to mediate resistance is evolutionary conserved, we tested ethylene in four plant species:Phaseolus vulgaris (Leguminosae), Zinnia elegans (Compositae), Zea mays (Poaceae, amonocotyledonous plant) and Polypodium vulgare (a fern). In all the cases ethylene causedresistance against B. cinerea. In pepper, ethylene induced the expression of CaSC1, asesquiterpene cyclase involved in phytoalexin biosynthesis, and chitinase activity. Both CaSC1and chitinase could be related to the observed resistance. Vanillylnonanamide is a pungentcompound present in some pepper fruits. This compound was also able to induce resistanceagainst Botrytis when exogenouly applied to pepper plants. The effect of vanillylnonanamide wasalso tested in the tomato ethylene signalling mutant Never ripe, where the induction worked, butin the wild type no induced resistance was observed. A similar result was obtained with salicylicacid: it only induced resistance to Botrytis cinerea in Never ripe, but not in the wild type. Theseresults suggest a cross-talk between ethylene and salicylic acid in the vanillylnonanamideinduced resistance. A non pungent capsaicinoid analogue, the capsinoid vanillylnonanoate, wasalso able to induce resistance against B. cinerea and P. capsici in pepper.