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Title: MOLECULAR CHARACTERISATION OF ENDOPHYTIC MORPHO-SPECIES ISOLATED FROM COCOA (THEOBROMA CACAO).

Author
item CROZIER, JAYNE - UNITED KINGDOM
item THOMAS, SARAH - UNITED KINGDOM
item Aime, Mary
item EVANS, HARRY - UNITED KINGDOM
item HOLMES, KEITH - UNITED KINGDOM

Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2006
Publication Date: 8/10/2006
Citation: Crozier, J., Thomas, S.E., Aime, M.C., Evans, H.C., Holmes, K.A. 2006. Molecular Characterisation of Fungal Endophytic Morphospecies Isolated from Stems and Pods of Theobroma Cacao. Plant Pathology. 55:783-791.

Interpretive Summary: Two serious fungal diseases of cocoa known as frosty pod rot and witches’ broom threaten the production of this crop in Central and South America. Cocoa is the major ingredient in chocolate, a major industry in the United States. Fungi that live inside healthy plants are called endophytes. They can often be used to protect a plant from disease-causing organisms. About 60 different endophytic fungi were isolated from cocoa trees 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. These fungi may compete with the pathogenic fungi to live inside the plant and, by keeping them out of the 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.

Technical Abstract: Endophytic fungi were isolated from healthy stems and pods of cocoa (Theobroma cacao) trees in natural forest ecosystems and agroecosystems in Latin America and West Africa. These fungi were collected for screening as a potential source of biocontrol agents for the basidiomycetous pathogens of cocoa in South and Central America, Moniliophthora roreri (frosty pod rot) and Crinipellis perniciosa (witches’ broom). Many of these isolates were morphologically unidentifiable as they failed to form fruiting structures in culture, or only produced arthrosporic stages. Affinities with basidiomycetes were suspected for many of these based on colony morphology. Approximately sixty of these isolates were selected for molecular identification by DNA extraction and sequence analysis of nuclear ribosomal DNA (rDNA). The large subunit (LSU) was chosen for initial sequencing because this region has been used most often for molecular systematics of basidiomycete fungi, and comprehensive LSU datasets were already available for sequence analyses. Results confirm that the majority of these isolates belong to the Basidiomycota, particularly to corticoid and polyporoid taxa. With LSU data alone, identification of the isolates was resolved at varying taxonomic levels (all to order, most to family, and many to genus). Some of the isolates came from rarely isolated genera, such as Byssomerulius, whilst the most commonly isolated basidiomycetous endophyte was a member of the cosmopolitan genus Coprinellus (Agaricales). The role of these fungi within the host and their potential as biological control agents is discussed.