title: Effects of Trichothecene Production on the Plant Defense Response and Fungal Physiology: Overexpression of the Trichoderma arundinaceum tri4 Gene in T. harzianum.
abstract: Trichothecenes are fungal sesquiterpenoid compounds, the majority of which have phytotoxic activity. They contaminate food and feed stocks, resulting in potential harm to animals and human beings. Trichoderma brevicompactum and T. arundinaceum produce trichodermin and harzianum A (HA), respectively, two trichothecenes that show different bioactive properties. Both compounds have remarkable antibiotic and cytotoxic activities, but in addition, trichodermin is highly phytotoxic, while HA lacks this activity when analyzed in vivo. Analysis of Fusarium trichothecene intermediates led to the conclusion that most of them, with the exception of the hydrocarbon precursor trichodiene (TD), have a detectable phytotoxic activity which is not directly related to the structural complexity of the intermediate. In the present work, the HA intermediate 12,13-epoxytrichothec-9-ene (EPT) was produced by expression of the T. arundinaceum tri4 gene in a transgenic T. harzianum strain that already produces TD after transformation with the T. arundinaceum tri5 gene. Purified EPT did not show antifungal or phytotoxic activity, while purified HA showed both antifungal and phytotoxic activities. However, the use of the transgenic T. harzianum tri4 strain induced a downregulation of defense-related genes in tomato plants and also downregulated plant genes involved in fungal root colonization. The production of EPT by the transgenic tri4 strain raised levels of erg1 expression and reduced squalene accumulation while not affecting levels of ergosterol. Together, these results indicate the complex interactions among trichothecene intermediates, fungal antagonists, and host plants.
authors.affiliation: Area of Microbiology, University School of Agricultural Engineers, University of León, Campus de Ponferrada, Ponferrada, Spain.
authors.forename: R E
authors.initials: RE
authors.lastname: Cardoza
authors.affiliation: Bacterial Foodborne Pathogen and Mycology Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, Illinois, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: McCormick
authors.affiliation: Area of Microbiology, University School of Agricultural Engineers, University of León, Campus de Ponferrada, Ponferrada, Spain.
authors.forename: M G
authors.initials: MG
authors.lastname: Malmierca
authors.affiliation: Area of Biochemistry and Molecular Biology, University of León, Campus de Ponferrada, Ponferrada, Spain.
authors.forename: E R
authors.initials: ER
authors.lastname: Olivera
authors.affiliation: Bacterial Foodborne Pathogen and Mycology Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, Illinois, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Alexander
authors.affiliation: Spanish-Portuguese Centre of Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, Salamanca, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Monte
authors.affiliation: Area of Microbiology, University School of Agricultural Engineers, University of León, Campus de Ponferrada, Ponferrada, Spain s.gutierrez@unileon.es.
authors.forename: S
authors.initials: S
authors.lastname: Gutiérrez
mesh_terms: D000935:Antifungal Agents / Q000378:metabolism; D053138:Cyclohexenes / Q000378:metabolism; D015536:Down-Regulation; D004875:Ergosterol / Q000378:metabolism; D005670:Fusarium / Q000737:chemistry / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D009154:Mutation; D012717:Sesquiterpenes / Q000378:metabolism; D013185:Squalene / Q000032:analysis; D014242:Trichoderma / Q000235:genetics* / Q000502:physiology*; D014243:Trichodermin / Q000378:metabolism / Q000633:toxicity; D014255:Trichothecenes / Q000096:biosynthesis* / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity
chemical_list: D000935:Antifungal Agents; D053138:Cyclohexenes; D012717:Sesquiterpenes; D014255:Trichothecenes; C087546:harzianum A; C063751:12,13-epoxytrichothec-9-ene; D014243:Trichodermin; C012075:trichodiene; D013185:Squalene; D004875:Ergosterol