title: Relevance of trichothecenes in fungal physiology: disruption of tri5 in Trichoderma arundinaceum.
abstract: Trichothecenes are sesquiterpenoid mycotoxins produced mainly by Fusarium species. Harzianum A (HA), a non-phytotoxic trichothecene produced by Trichoderma arundinaceum, has recently been found to have antagonistic activity against fungal plant pathogens and to induce plant genes involved in defense responses. In the present work, we have shown that disruption of the T. arundinaceum tri5 gene, which encodes a terpene synthase, stops the production of HA, alters the expression of other tri genes involved in HA biosynthesis, and alters the expression of hmgR, dpp1, erg9, erg1, and erg7, all genes involved in terpene biosynthetic pathways. An increase in the level of ergosterol biosynthesis was also observed in the tri5 disrupted transformant in comparison with the wild type strain. The loss of HA also resulted in a drastic reduction of the biocontrol activity of the transformants against the phytopathogenic fungi Botrytis cinerea and Rhizoctonia solani. Finally, the effect of tri5 gene disruption on the regulation and balance of intermediates in terpene biosynthetic pathways, as well as the hypothetical physiological role of trichothecenes, both inter- and intracellularly, on regulation and biocontrol, are discussed.
authors: Area of Microbiology, University School of Agricultural Engineers, University of León, Campus de Ponferrada, Avda. Astorga s/n, 24400 Ponferrada, Spain.
authors: Mónica G
authors: MG
authors: Malmierca
authors: Rosa Elena
authors: RE
authors: Cardoza
authors: Nancy J
authors: NJ
authors: Alexander
authors: Susan P
authors: SP
authors: McCormick
authors: Isidro G
authors: IG
authors: Collado
authors: Rosa
authors: R
authors: Hermosa
authors: Enrique
authors: E
authors: Monte
authors: Santiago
authors: S
authors: Gutiérrez
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002688:Chitinases / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics; D004875:Ergosterol / Q000096:biosynthesis; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D023061:Gene Order; D005816:Genetic Complementation Test; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D013172:Spores, Fungal / Q000235:genetics / Q000254:growth & development; D013185:Squalene / Q000378:metabolism; D014242:Trichoderma / Q000502:physiology*; D014255:Trichothecenes / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D014255:Trichothecenes; C087546:harzianum A; D013185:Squalene; D006903:Hydroxymethylglutaryl CoA Reductases; D002688:Chitinases; D004875:Ergosterol