Small signals lead to big changes: Deciphering the mechanisms behind Peptide-Induced Resistance in plants

Abstract

To cope with biotic stresses, such as pest and pathogen attacks, plants have evolved a broad variety of adaptative defense strategies. Sometimes plant perception of external stimuli induces an enhanced resistance state that confers protection against a future attack in local and distal tissues. This state is known as “Induced Resistance” and can be triggered by both biological and non-biological stimuli. In this thesis, we found that peptides from different species can induce resistance against the necrotrophic fungus Plectosphaerella cucumerina in the taxonomically distant species Arabidopsis thaliana at very low concentrations. Noteworthy, of the tested peptides Systemin conferred a high degree of protection in Arabidopsis from very low concentrations, showing an optimal threshold of action, resembling the mode of action of a phytohormone or other IR elicitors. Thus, the following analyses were focused on deciphering the mechanisms of Systemin-Induced Resistance (Sys-IR) in Arabidopsis and in tomato.