Project description:Recognition of microbial patterns by host pattern recognition receptors is a key step in immune activation in multicellular eukaryotes. Peptidoglycans (PGN) are major components of bacterial cell walls and possess immunity-stimulating activities in metazoans and plants. Here, we show that PGN sensing in Arabidopsis thaliana requires three LysM domain proteins, LYM1, LYM3 and CERK1. A 24 DNA microarray study using toral RNA from three Arabidopsis mutants (lym1-1, lym3-1, cerk1-2) as well as wild type treated with water or peptidoglycan.