The fungal elicitor AsES requires a functional ethylene pathway to activate the innate immunity in strawberry

Abstract

AsES (Acremonium strictum Elicitor Subtilisin) is a fungal elicitor that activates innate immunity conferring disease resistance in strawberry (Fragaria x ananassa Duch.), Arabidopsis, and other plant species. The aim of the present work was to evaluate the involvement of ethylene (ET) signalling pathway in AsES‐mediated immune response in strawberry. ET production and expression of the genes responsible for ET synthesis, perception, and response, were measured after AsES treatment. The ROS (H2O2) accumulation and immunity induced by AsES were studied after ET perception was blocked by 1‐methylcyclopropene (1‐MCP). Biochemical and molecular results showed that AsES induced a marked increase in local and systemic biosynthesis of ET, both in a biphasic manner. Blocking of ET perception by 1‐MCP prior to AsES induction reduced production of ROS (H2O2), and unables AsES to elicit defense against fungal pathogens of different lifestyles such as Botrytis cinerea (necrotrophic) and Colletotrichum acutatum (hemibiotrophic). These findings contribute to elucidate the mode of action of the novel elicitor subtilase AsES, specifically regarding the role of ET signalling in the activation of plant innate immunity in addition to the multitude of processes regulated by ET in plants.