A study of the mechanisms of antagonism by the biocontrol fungi <i>Trichoderma </i>against wood decay basidiomycetes

Environmental concern regarding the use of hazardous wood preservatives is of increasing concern, and biological control may provide an attractive alternative to the use of toxic chemicals for wood protection. <i>Trichoderma </i>isolates are among the most widely researched biological control agents for the protection of agricultural crops from a variety of plant diseases and have more recently been investigated for bioprotection of wood products.<br/><br/>Screening of fungal antagonists is the first most important step in selection of potential biocontrol agents. Preliminary interaction studies were carried out between <i>Trichoderma </i>spp. and selected basidiomycetes on both nutrient rich media and a low nutrient media devised to give a closer representation of the nutritional consistency of wood. Results indicated that the outcome of interactions was dependent on the media type.<br/><br/>Individual antagonistic mechanisms of <i>Trichoderma </i>(soluble metabolite, volatile antibiotics, laminarinase and chitinase lytic enzymes) against <i>Neolentinus lepideus</i> and <i>Trametes versicolor</i> fungi indicated that these were also dependent on media type. Study of production of iron chelating siderophores by <i>Trichoderma </i>species indicated that they may also play a significant role in antagonism against basidiomycetes by iron competition. One of the major aims of the work was to identify the relative importance of individual antagonistic mechanisms of <i>Trichoderma </i>that would be of importance during interaction with wood decay basidiomycetes in the natural substrate, i.e., wood. Statistical comparisons were carried out between the % weight loss of wood blocks after exposure to selected basidiomycetes, with individual antagonistic responses observed against these same wood decay fungi using agar test systems. Results indicate that the relative importance of individual antagonistic responses exhibited by <i>Trichoderma </i>spp. in determining the degree of wood protection is dependent on the following factors: 1) target pathogen, 2) <i>Trichoderma </i>spp. and 3) the media in which the responses were detected. This project has important commercial implications since through a better understanding of the strategies of the antagonists, strains can be developed to exaggerate their more important antagonistic mechanisms or to better target, specific decay fungi. Also knowledge gained on the potential of certain metabolites and volatiles can be adapted in commercial production of safer wood protectants which may replace toxic chemical preservatives currently in use.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral Thesis

Year dc:date.issued

1993

Author dc:creator

• Srinivasan, Usha

Language dc:language

eng

Identifier

oai:rke.abertay.ac.uk:studenttheses/78aceb82-d25f-4f98-91fe-ed80a37fe778

OAI identifier oai:identifier

oai:rke.abertay.ac.uk:studenttheses/78aceb82-d25f-4f98-91fe-ed80a37fe778