Ecological studies of Trichoderma-plant interactions using fluorescent reporter systems

Trichoderma spp. are ubiquitous soil-borne ascomycetous fungi with a high capacity for biocontrol of fungal phytopathogens. This capability has led to substantial exploitation and currently Trichoderma spp. represent one third of all commercial fungal biocontrol agents (BCAs) sold globally. Within our research group we have developed a commercial T. atroviride BCA (LU132) for control of Botrytis cinerea in grapevines and Sclerotium cepivorum in onions. To facilitate rhizosphere studies, a GFP-marked LU132 strain was created and used for root-interaction experiments, however autofluorescence of the onion root interfered with our ability to visualise the interaction. In this study we have transformed LU132 with two additional reporter genes: DsRed (encoding red fluorescent protein) and BFP (encoding blue fluorescent protein). The aim of this work is to develop and evaluate three different biocontrol reporter systems for in situ monitoring of fungal biocontrol inoculants. In particular we will evaluate the potential of each reporter system for use in interactions involving autofluorescence. Experiments are currently under way to investigate how well these systems work and if there are any changes in growth, morphology, biocontrol efficiency and colonisation of onion roots compared to the wild type. These biocontrol reporter strains will enable us to gain insight into fungal growth and activity and into important abiotic and biotic factors affecting biocontrol efficac