Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2008
Publication Date: 7/3/2008
Citation: Weaver, M.A., Kenerley, C.M. 2008. Competitiveness of a Genetically Engineered Strain of Trichoderma virens. Mycopathologia 166:51-59.
Interpretive Summary: A fungal biological control agent, Trichoderma virens, has been genetically engineered to enable it to degrade a class of pesticides. Research presented here demonstrates that the genetically engineered strain is more competitive than the wild-type, progenitor strain. Because of the surprising nature of this finding and disagreements among ecologists regarding experimental design for competition experiments, a novel experimental approach was developed that more realistically simulated the introduction of the genetically engineered strain into an environment with wild-type competitors. This new approach confirmed the superior competitiveness of the genetically engineered strain. This competitiveness should be considered in assessing the risks off-site movement or persistence of genetically engineered microorganisms.
Technical Abstract: The intraspecific competitiveness of a genetically engineered strain of Trichoderma virens was assessed relative to the non-transformed, progenitor strain and an isogenic, auxotrophic strain using a replacement series design. The transformed strain was less fit, but appeared more competitive than the wild-type or the auxotroph in this assay. To validate this finding and to evaluate the ability of a strain to establish in an environment occupied by a competitor another experimental approach was developed. In various treatments the transformed strain was unaffected or only slightly inhibited by a competing strain. In contrast, the wild-type and auxotrophic strain were strongly inhibited by the presence of the transformed strain. These findings support the conclusion that this genetically engineered strain is more competitive than the wild type strain and thus may be more persistent in the environment.