Elicitors and Ethylene Trigger Defense Responses in Plants

Abstract

Infected plants often produce large amounts of ethylene. The possible role of this hormone in plant-microorganism interaction is poorly understood. We have previously demonstrated that ethylene protects melon plants against Colletotrichum lagenarium, the causal agent of anthracnose (1). This has led to the hypothesis that ethylene could be a message which triggers defense responses in plants. The increased synthesis of proteins associated to defense mechanisms during plant-microorganism interactions, and their elicitation by ethylene, or via ethylene by fungal elicitors, are successively reported. The 3 proteins considered in this study are cell wall hydroxyproline-rich glycoprotein (HRGP, which strengthens the plant cell wall), chitinase (which digests chitin-containing fungal cell wall), and proteolytic inhibitors (which neutralize the trypsin-like proteases of plant pathogens).