The Molecular Characterisation of Trichoderma Hamatum Effects on Plant Growth and Biocontrol
Harris, Beverley D.
Thesis or dissertation
University of Exeter
Expanding global populations, unequal food distribution and disease pressure suggest food poverty is increasing. Consequently, much attention is focussed on alternative natural methods in which to increase agricultural yield. Previously, it was observed that Trichoderma hamatum strain GD12 and its respective N-acetyl-β-D-Glucosamine mutant ∆Thnag:hph promoted plant biomass and fitness that, as a result, may provide a credible natural alternative to synthetic fertilisers. However, on a molecular level, the manner in which this is achieved has not been fully elucidated. In this thesis, I report the biofertiliser effect of GD12 and mutant ∆Thnag::hph once applied to autoclaved peat microcosms as sole applications. Furthermore, I demonstrate the biocontrol ability of GD12 when co-inoculated with Sclerotinia sclerotiorum or Rhizoctonia solani and reveal, that once mycelium co-inoculation has occurred, GD12 increase plant biomass and provide protection; whilst ∆Thnag::hph does not. Consequently, I challenged the biocontrol effects of Trichoderma metabolite extract where I validate that both Trichoderma wild type GD12 and mutant ∆Thnag::hph are incapable of suppressing pathogen growth. Subsequently, I characterised the up-regulated signatures associated with GD12 and ∆Thnag::hph using LC-MS techniques where unique compounds were discovered from each strain of Trichoderma. In conclusion, I provide evidence that N-acetyl-β-D-Glucosamine mutation bring about metabolomic changes that affect the fungal secretome which, in turn, alters plant phenotype, fitness and germination. Furthermore, I have shown that these effects are species specific and depend upon pathogen, plant and fungal properties. However, further investigations are needed to fully elucidate the compound(s) responsible for biocontrol and biofertilisation; especially plant-specific effects that take place as a consequence of fungal activity.
University of Exeter
Ryder et al (2012) Saprotrophic competitiveness and biocontrol fitness of a genetically modified strain of the plant-growth-promoting fungus Trichoderma hamatum GD12. Microbiology. 158(Pt 1), 84.
Studholme et al (2013) Investigating the beneficial traits of Trichoderma hamatum GD12 for sustainable agriculture—insights from genomics. Frontiers in plant science. 4, 258, 1-13.
PhD in Biological Sciences