Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2008
Publication Date: July 1, 2008
Citation: Thomas, S.E., Crozier, J., Aime, M.C., Evans, H.C., Holmes, K.A. 2008. Molecular characterization of fungal endophytic morphospecies associated with the indigenous forest tree, Theobroma gileri in Ecuador. Mycological Research. 112:852-860.
Interpretive Summary: The production of chocolate is a major industry in the United States of which cocoa is the main ingredient. Two serious diseases of cocoa plants known as frosty pod rot and witches’ broom threaten the production of this crop in Central and South America. Inside healthy plants live many kinds of fungi that are called endophytes that seem to protect the plant from disease-causing organisms. The endophytes that occur within the cocoa plant and its close relative have been isolated from the wild in South America. In this research many different kinds of endophytes were discovered but could not be identified because they did not form the structures needed for their identification. Molecular sequences were used to identify these endophytic fungi, most of which are related to the mushroom-like fungi. The endophytic fungi may outcompete the pathogens to live inside the cocoa plants and, by keeping the pathogens out of healthy plants, serve as biological control agents. In addition, these endophytic fungi may produce chemicals that keep away the disease-causing organisms. This research will be used by plant pathologists who are working to control diseases of cocoa.
Fungal endophytes were isolated from healthy stems and pods of Theobroma gileri, an alternative host of the frosty pod rot pathogen of cacao. Identification of sporulating isolates was undertaken; however, many of the endophytes isolated could not be identified morphologically as they were non-sporulating, or only produced arthrosporic stages in culture. These isolates were grouped into 46 different morphological species according to their colony morphology. Many of these morphospecies were assumed to be basidiomycetes and were therefore of interest as potential biological control agents of the basidiomycetous pathogens of Theobroma cacao—Moniliophthora roreri (frosty pod rot pathogen) and M. perniciosa (causal agent of witches’ broom disease). The morphospecies were further characterised by molecular analyses. Amplification of the large sub unit (LSU) revealed a total of 31 different taxa of which 15 were basidiomycetes belonging to the class Agaricomycetes, and 16 ascomycetes primarily belonging to the Sordariomycetes.