title: The LysM receptor-like kinase LysM RLK1 is required to activate defense and abiotic-stress responses induced by overexpression of fungal chitinases in Arabidopsis plants.
abstract: Application of crab shell chitin or pentamer chitin oligosaccharide to Arabidopsis seedlings increased tolerance to salinity in wild-type but not in knockout mutants of the LysM Receptor-Like Kinase1 (CERK1/LysM RLK1) gene, known to play a critical role in signaling defense responses induced by exogenous chitin. Arabidopsis plants overexpressing the endochitinase chit36 and hexoaminidase excy1 genes from the fungus Trichoderma asperelleoides T203 showed increased tolerance to salinity, heavy-metal stresses, and Botrytis cinerea infection. Resistant lines, overexpressing fungal chitinases at different levels, were outcrossed to lysm rlk1 mutants. Independent homozygous hybrids lost resistance to biotic and abiotic stresses, despite enhanced chitinase activity. Expression analysis of 270 stress-related genes, including those induced by reactive oxygen species (ROS) and chitin, revealed constant up-regulation (at least twofold) of 10 genes in the chitinase-overexpressing line and an additional 76 salt-induced genes whose expression was not elevated in the lysm rlk1 knockout mutant or the hybrids harboring the mutation. These findings elucidate that chitin-induced signaling mediated by LysM RLK1 receptor is not limited to biotic stress response but also encompasses abiotic-stress signaling and can be conveyed by ectopic expression of chitinases in plants.
authors.affiliation: Genes and Small Molecules, AG Willmitzer, Max-Planck-Institut of Molecular Plant Physiology, Am Muhlenberg 1, D-14476 Potsdam-Golm, Germany.
authors.forename: Yariv
authors.initials: Y
authors.lastname: Brotman
authors.forename: Udi
authors.initials: U
authors.lastname: Landau
authors.forename: Smadar
authors.initials: S
authors.lastname: Pnini
authors.forename: Jan
authors.initials: J
authors.lastname: Lisec
authors.forename: Salma
authors.initials: S
authors.lastname: Balazadeh
authors.forename: Bernd
authors.initials: B
authors.lastname: Mueller-Roeber
authors.forename: Aviah
authors.initials: A
authors.lastname: Zilberstein
authors.forename: Lothar
authors.initials: L
authors.lastname: Willmitzer
authors.forename: Ilan
authors.initials: I
authors.lastname: Chet
authors.forename: Ada
authors.initials: A
authors.lastname: Viterbo
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020171:Botrytis / Q000502:physiology; D002688:Chitinases / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010935:Plant Diseases / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D014242:Trichoderma / Q000201:enzymology
chemical_list: D029681:Arabidopsis Proteins; D005656:Fungal Proteins; C525882:CERK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D002688:Chitinases