title: Trichoderma-plant root colonization: escaping early plant defense responses and activation of the antioxidant machinery for saline stress tolerance.
abstract: Trichoderma spp. are versatile opportunistic plant symbionts which can colonize the apoplast of plant roots. Microarrays analysis of Arabidopsis thaliana roots inoculated with Trichoderma asperelloides T203, coupled with qPCR analysis of 137 stress responsive genes and transcription factors, revealed wide gene transcript reprogramming, proceeded by a transient repression of the plant immune responses supposedly to allow root colonization. Enhancement in the expression of WRKY18 and WRKY40, which stimulate JA-signaling via suppression of JAZ repressors and negatively regulate the expression of the defense genes FMO1, PAD3 and CYP71A13, was detected in Arabidopsis roots upon Trichoderma colonization. Reduced root colonization was observed in the wrky18/wrky40 double mutant line, while partial phenotypic complementation was achieved by over-expressing WRKY40 in the wrky18 wrky40 background. On the other hand increased colonization rate was found in roots of the FMO1 knockout mutant. Trichoderma spp. stimulate plant growth and resistance to a wide range of adverse environmental conditions. Arabidopsis and cucumber (Cucumis sativus L.) plants treated with Trichoderma prior to salt stress imposition show significantly improved seed germination. In addition, Trichoderma treatment affects the expression of several genes related to osmo-protection and general oxidative stress in roots of both plants. The MDAR gene coding for monodehydroascorbate reductase is significantly up-regulated and, accordingly, the pool of reduced ascorbic acid was found to be increased in Trichoderma treated plants. 1-Aminocyclopropane-1-carboxylate (ACC)-deaminase silenced Trichoderma mutants were less effective in providing tolerance to salt stress, suggesting that Trichoderma, similarly to ACC deaminase producing bacteria, can ameliorate plant growth under conditions of abiotic stress, by lowering ameliorating increases in ethylene levels as well as promoting an elevated antioxidative capacity.
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, Potsdam-Golm, Germany. brotman@mpimp-golm.mpg.de
authors.forename: Yariv
authors.initials: Y
authors.lastname: Brotman
authors.forename: Udi
authors.initials: U
authors.lastname: Landau
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Cuadros-Inostroza
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tohge
authors.forename: Tohge
authors.initials: T
authors.lastname: Takayuki
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.forename: Ilan
authors.initials: I
authors.lastname: Chet
authors.forename: Ada
authors.initials: A
authors.lastname: Viterbo
authors.forename: Lothar
authors.initials: L
authors.lastname: Willmitzer
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D019755:Carbon-Carbon Lyases / Q000235:genetics* / Q000378:metabolism; D018553:Cucumis sativus / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000502:physiology; D005030:Ethylenes / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress / Q000502:physiology; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018517:Plant Roots / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000502:physiology; D030821:Plants, Genetically Modified; D055049:Salt Tolerance; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014242:Trichoderma / Q000235:genetics / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D005030:Ethylenes; D005656:Fungal Proteins; D014157:Transcription Factors; D012965:Sodium Chloride; C036216:ethylene; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases