title: Trichodiene Production in a Trichoderma harzianum erg1-Silenced Strain Provides Evidence of the Importance of the Sterol Biosynthetic Pathway in Inducing Plant Defense-Related Gene Expression.
abstract: Trichoderma species are often used as biocontrol agents against plant-pathogenic fungi. A complex molecular interaction occurs among the biocontrol agent, the antagonistic fungus, and the plant. Terpenes and sterols produced by the biocontrol fungus have been found to affect gene expression in both the antagonistic fungus and the plant. The terpene trichodiene (TD) elicits the expression of genes related to tomato defense and to Botrytis virulence. We show here that TD itself is able to induce the expression of Botrytis genes involved in the synthesis of botrydial (BOT) and also induces terpene gene expression in Trichoderma spp. The terpene ergosterol, in addition to its role as a structural component of the fungal cell membranes, acts as an elicitor of defense response in plants. In the present work, using a transformant of T. harzianum, which is silenced in the erg1 gene and accumulates high levels of squalene, we show that this ergosterol precursor also acts as an important elicitor molecule of tomato defense-related genes and induces Botrytis genes involved in BOT biosynthesis, in both cases, in a concentration-dependent manner. Our data emphasize the importance of a balance of squalene and ergosterol in fungal interactions as well as in the biocontrol activity of Trichoderma spp.
authors.affiliation: 1 Area of Microbiology, Universitary School of Agricultural Engineers, University of León, Campus de Ponferrada. Avda, Astorga s/n, 24400 Ponferrada, Spain;
authors.forename: M G
authors.initials: MG
authors.lastname: Malmierca
authors.affiliation: 2 Bacterial Foodborne Pathogen and Mycology Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, IL 61604-3902, U.S.A.;
authors.forename: S P
authors.initials: SP
authors.lastname: McCormick
authors.affiliation: 1 Area of Microbiology, Universitary School of Agricultural Engineers, University of León, Campus de Ponferrada. Avda, Astorga s/n, 24400 Ponferrada, Spain;
authors.forename: R E
authors.initials: RE
authors.lastname: Cardoza
authors.affiliation: 3 Spanish-Portuguese Centre of Agricultural Research (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185 Salamanca, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Monte
authors.affiliation: 2 Bacterial Foodborne Pathogen and Mycology Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, IL 61604-3902, U.S.A.;
authors.forename: N J
authors.initials: NJ
authors.lastname: Alexander
authors.affiliation: 1 Area of Microbiology, Universitary School of Agricultural Engineers, University of León, Campus de Ponferrada. Avda, Astorga s/n, 24400 Ponferrada, Spain;
authors.forename: S
authors.initials: S
authors.lastname: Gutiérrez
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics; D020171:Botrytis / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D053138:Cyclohexenes / Q000378:metabolism*; D060467:Disease Resistance / Q000235:genetics; D004875:Ergosterol / Q000096:biosynthesis*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D054884:Host-Pathogen Interactions / Q000235:genetics; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012717:Sesquiterpenes / Q000378:metabolism*; D013185:Squalene / Q000378:metabolism; D014242:Trichoderma / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
chemical_list: D053138:Cyclohexenes; D005656:Fungal Proteins; D012717:Sesquiterpenes; C012075:trichodiene; D013185:Squalene; D004875:Ergosterol