The N-end rule pathway : a novel regulator of plant immunity
M. SOREL (1), R. De Marchi (1), B. Mooney (2), I. Fudal (3), K. Goslin (1), K. Kwasniewska (4), P. Ryan (4), M. Pfalz (5), J. Kroymann (5), S. Pollmann (6), A. Feechan (7), F. Wellmer (4), S. Rivas (8), E. Graciet (1) (1) Maynooth University, Biology department, Ireland; (2) Maynooth university, Biology department, Ireland; (3) INRA, UMR BIOGER, France; (4) Trinity College Dublin, Smurfit Institute of Genetics, Ireland; (5) CNRS, Laboratoire Ecologie Systematique Evolution, France; (6) Centro de Biotecnologia y Genomica de Plantas, U.P.M, Spain; (7) UCD Earth Institute and School of Biology and Environmental Science, Ireland; (8) INRA, CNRS, Laboratoire des Interactions Plantes-Microorganismes, France

The timing and amplitude of the defense response are crucial for the plant’s resistance against pathogens and are the result of a balance between negative and positive regulators, including complex hormonal crosstalks. The ubiquitin-proteasome system is a major regulator of protein stability and has been shown to regulate plant immunity. This work focuses on the regulation of plant responses to pathogens by the N-end rule pathway, a subset of the ubiquitin-proteasome system. The N-end rule pathway targets proteins for degradation based on the identity of their N-terminal residue, so that proteins bearing so-called destabilizing residues at their N-terminus can be ubiquitylated and degraded. Arginine transferases play an important role, as they conjugate arginine, a destabilizing residue, to the N-terminus of protein substrates, thus targeting them for degradation by the N-end rule pathway. Transcriptomics analysis of an Arabidopsis thaliana mutant deficient for arginine transferase activity revealed a downregulation of genes associated with jasmonic acid and glucosinolates, both of which play important roles in the response of plants to biotic stressors. Metabolite measurements further indicate that the mutant accumulates lower levels of jasmonic acid and glucosinolates when compared to the wild type. In agreement with these results, Arabidopsis mutants impaired for this branch of the N-end rule pathway are more susceptible to a range of bacterial and fungal pathogens.

Abstract Number: P16-471
Session Type: Poster