title: Saprotrophic competitiveness and biocontrol fitness of a genetically modified strain of the plant-growth-promoting fungus Trichoderma hamatum GD12.
abstract: Trichoderma species are ubiquitous soil fungi that hold enormous potential for the development of credible alternatives to agrochemicals and synthetic fertilizers in sustainable crop production. In this paper, we show that substantial improvements in plant productivity can be met by genetic modification of a plant-growth-promoting and biocontrol strain of Trichoderma hamatum, but that these improvements are obtained in the absence of disease pressure only. Using a quantitative monoclonal antibody-based ELISA, we show that an N-acetyl-β-d-glucosaminidase-deficient mutant of T. hamatum, generated by insertional mutagenesis of the corresponding gene, has impaired saprotrophic competitiveness during antagonistic interactions with Rhizoctonia solani in soil. Furthermore, its fitness as a biocontrol agent of the pre-emergence damping-off pathogen Sclerotinia sclerotiorum is significantly reduced, and its ability to promote plant growth is constrained by the presence of both pathogens. This work shows that while gains in T. hamatum-mediated plant-growth-promotion can be met through genetic manipulation of a single beneficial trait, such a modification has negative impacts on other aspects of its biology and ecology that contribute to its success as a saprotrophic competitor and antagonist of soil-borne pathogens. The work has important implications for fungal morphogenesis, demonstrating a clear link between hyphal architecture and secretory potential. Furthermore, it highlights the need for a holistic approach to the development of genetically modified Trichoderma strains for use as crop stimulants and biocontrol agents in plant agriculture.
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
authors.forename: Lauren S
authors.initials: LS
authors.lastname: Ryder
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
authors.forename: Beverley D
authors.initials: BD
authors.lastname: Harris
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
authors.forename: Darren M
authors.initials: DM
authors.lastname: Soanes
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kershaw
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Talbot
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Thornton
mesh_terms: D000118:Acetylglucosaminidase / Q000235:genetics* / Q000378:metabolism; D000898:Antibiosis; D001203:Ascomycota / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005818:Genetic Engineering; D018545:Lactuca / Q000254:growth & development / Q000382:microbiology*; D008969:Molecular Sequence Data; D010572:Pest Control, Biological; D010935:Plant Diseases / Q000382:microbiology*; D012232:Rhizoctonia / Q000254:growth & development* / Q000502:physiology; D012988:Soil Microbiology; D013172:Spores, Fungal / Q000235:genetics / Q000254:growth & development; D014242:Trichoderma / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D005656:Fungal Proteins; D000118:Acetylglucosaminidase