The Arabidopsis thaliana LSU peptides: An interactomics-based approach to unravel their role in the plant stress response

Abstract

Plants defend themselves against pathogens and abiotic stresses using a wide arsenal of defence mechanisms. The model plant Arabidopsis thaliana has four members of the LSU (Low Sulfur Upregulated) gene family (LSU1-4) encoding small proteins with 59-89% sequence similarity and homologues in several other plants and major crops. Originally, the LSU peptides were characterized as induced during sulfur deficiencies, but recent studies suggest an important regulatory role in various plant processes, including development and stress responses. Large scale interactome studies based on yeast two-hybrid (Y2H) analyses show that the LSU peptides interact with a large number of other A. thaliana proteins with different functions. In addition, LSU peptides were identified as targets of virulence effectors of different (hemi)biotrophic plant pathogens. There are also descriptions of several phenotypes of A. thaliana mutants with an altered expression of the LSU peptides, such as an altered sensitivity to both (hemi)biotrophic and necrotrophic pathogens, certain abiotic stresses and distortions in flower development. Currently, these studies suggest that the LSU peptides would function as important hub proteins in the integration and regulation of environmental signals. However, the precise molecular function of the LSU peptides still remains unknown. The goal of this project is to better understand the in planta interaction potential of the LSU peptides and to unravel their precise role in the plant stress response. For this purpose, different complimentary in planta protein interaction analyses will be combined with protein localisation studies, gene expression analyses and a thorough functional analysis of the LSU peptides and confirmed interactors. This will be done mainly through phenotyping of mutant A. thaliana lines using a wide range of pathogen and abiotic stress tests.status: publishe