title: Trichoderma mitogen-activated protein kinase signaling is involved in induction of plant systemic resistance.
abstract: The role of a mitogen-activated protein kinase (MAPK) TmkA in inducing systemic resistance in cucumber against the bacterial pathogen Pseudomonas syringae pv. lacrymans was investigated by using tmkA loss-of-function mutants of Trichoderma virens. In an assay where Trichoderma spores were germinated in proximity to cucumber roots, the mutants were able to colonize the plant roots as effectively as the wild-type strain but failed to induce full systemic resistance against the leaf pathogen. Interactions with the plant roots enhanced the level of tmkA transcript in T. virens and its homologue in Trichoderma asperellum. At the protein level, we could detect the activation of two forms reacting to the phospho-p44/42 MAPK antibody. Biocontrol experiments demonstrated that the tmkA mutants retain their biocontrol potential against Rhizoctonia solani in soil but are not effective against Sclerotium rolfsii in reducing disease incidence. Our results show that, unlike in many plant-pathogen interactions, Trichoderma TmkA MAPK is not involved in limited root colonization. Trichoderma, however, needs MAPK signaling in order to induce full systemic resistance in the plant.
authors.affiliation: Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel. ada.viterbo@weizmann.ac.il
authors.forename: Ada
authors.initials: A
authors.lastname: Viterbo
authors.forename: Michal
authors.initials: M
authors.lastname: Harel
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Horwitz
authors.forename: Ilan
authors.initials: I
authors.lastname: Chet
authors.forename: Prasun K
authors.initials: PK
authors.lastname: Mukherjee
mesh_terms: D018553:Cucumis sativus / Q000276:immunology* / Q000382:microbiology; D007887:Fabaceae / Q000382:microbiology; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010572:Pest Control, Biological; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology; D020072:Polyporales / Q000254:growth & development / Q000472:pathogenicity; D044224:Pseudomonas syringae / Q000254:growth & development / Q000472:pathogenicity*; D012232:Rhizoctonia / Q000254:growth & development / Q000472:pathogenicity; D015398:Signal Transduction; D014242:Trichoderma / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D020928:Mitogen-Activated Protein Kinases