title: Trichoderma-induced plant immunity likely involves both hormonal- and camalexin-dependent mechanisms in Arabidopsis thaliana and confers resistance against necrotrophic fungi Botrytis cinerea.
abstract: Filamentous fungi belonging to the genus Trichoderma have long been recognized as agents for the biocontrol of plant diseases. In this work, we investigated the mechanisms involved in the defense responses of Arabidopsis thaliana seedlings elicited by co-culture with Trichoderma virens and Trichoderma atroviride. Interaction of plant roots with fungal mycelium induced growth and defense responses, indicating that both processes are not inherently antagonist. Expression studies of the pathogenesis-related reporter markers pPr1a:uidA and pLox2:uidA in response to T. virens or T. atroviride provided evidence that the defense signaling pathway activated by these fungi involves salicylic acid (SA) and/or jasmonic acid (JA) depending on the amount of conidia inoculated. Moreover, we found that Arabidopsis seedlings colonized by Trichoderma accumulated hydrogen peroxide and camalexin in leaves. When grown under axenic conditions, T. virens produced indole-3-carboxaldehyde (ICAld) a tryptophan-derived compound with activity in plant development. In Arabidopsis seedlings whose roots are in contact with T. virens or T. atroviride, and challenged with Botrytis cinerea in leaves, disease severity was significantly reduced compared to axenically grown seedlings. Our results indicate that the defense responses elicited by Trichoderma in Arabidopsis are complex and involve the canonical defense hormones SA and JA as well as camalexin, which may be important factors in boosting plant immunity.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México.
authors.forename: Hexon Angel
authors.initials: HA
authors.lastname: Contreras-Cornejo
authors.forename: Lourdes
authors.initials: L
authors.lastname: Macías-Rodríguez
authors.forename: Elda
authors.initials: E
authors.lastname: Beltrán-Peña
authors.forename: Alfredo
authors.initials: A
authors.lastname: Herrera-Estrella
authors.forename: José
authors.initials: J
authors.lastname: López-Bucio
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000382:microbiology*; D018533:Biomass; D020171:Botrytis / Q000187:drug effects / Q000502:physiology; D003517:Cyclopentanes / Q000378:metabolism; D060467:Disease Resistance / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D008401:Gas Chromatography-Mass Spectrometry; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D007211:Indoles / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D057865:Plant Immunity / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D018517:Plant Roots / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D020156:Salicylic Acid / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D013844:Thiazoles / Q000494:pharmacology*; D014242:Trichoderma / Q000187:drug effects / Q000276:immunology*; D000094162:Phytoalexins
chemical_list: D003517:Cyclopentanes; D006861:Hydrogen Peroxide; D007211:Indoles; D054883:Oxylipins; D010937:Plant Growth Regulators; D020156:Salicylic Acid; D013844:Thiazoles; C102405:camalexin; D000094162:Phytoalexins; C011006:jasmonic acid; C012381:indole-3-carbaldehyde