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United States Department of Agriculture

Agricultural Research Service

Research Project: SYSTEMATICS OF MICROFUNGI USED IN BIOLOGICAL CONTROL OF PLANT DISEASES AND INSECT PESTS Title: Trichoderma stromaticum and its overseas relatives

Authors
item Samuels, Gary
item Ismaiel, Ed
item DE Souza, J. -
item Chaverri, P. -

Submitted to: Mycological Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 26, 2011
Publication Date: February 22, 2011
Citation: Samuels, G.J., Ismaiel, A.A., De Souza, J., Chaverri, P. 2011. Trichoderma stromaticum and its overseas relatives. Mycological Progress. 11:215-254.

Interpretive Summary: One of the most serious diseases of the chocolate plant is known as witches’ broom disease of cacao in South America. It can be controlled by a species of fungus. This fungus has been described as one species although some scientists have suggested that more than one species was included under this name. Based on a study of biological characters and DNA sequences, this research demonstrated that this biocontrol species is only one variable species. In addition this biocontrol fungus was determined to also be useful in controlling another disease of cacao known as frosty pod rot. These molecular data suggest that the biocontrol fungi may have come to South America from Africa on a related mushroom species. This research indicates that potentially more powerful biocontrol agents of these cacao diseases may be found either in native forests of South America or West Africa on related mushrooms. Plant pathologists will use this research to search for more effective isolates of fungi that control cacao diseases.

Technical Abstract: Trichoderma stromaticum, T. rossicum and newly discovered species form a new lineage in Trichoderma. Phylogenetic and phenotypic diversity in Trichoderma stromaticum are examined in light of reported differences in ecological parameters and AFLP patterns. Multilocus phylogenetic analysis using 4 genes (tef1, rbp2, cal, ech42) did not reveal phylogenetic basis for the two reported divergent AFLP patterns or for ecological parameters; however, this analysis indicates incomplete speciation with one supported clade, corresponding to AFLP Group 2, derived from within T. stromaticum. Trichoderma stromaticum is known only from tropical America and is typically found in association with Theobroma cacao infected with Moniliophthora roreri. Strains of T. stromaticum have been isolated as endophytes from stems of Theo. cacao and strains of T. stromaticum have been isolated from pseudostroma of M. roreri in Peru and Ecuador. There are no species of Trichoderma found in America that are closely related to T. stromaticum. The closest relatives of T. stromaticum include T. rossicum and its newly described sister T. barbatum, both north temperate species, and the new species T. ivoriensis (Côte d’Ivoire), are found in west Africa and Thailand; they are described here as new species: T. ivoriensis, T. PPRI3359, T. caesariatum (Hypocrea teleomorph), T. lanuginis (teleomorph = Hypocrea sp., Cameroon), T. medusae (teleomorph = Hypocrea sp., Cameroon), T. caesariatum (teleomorph = Hypocrea sp., Thailand, T. floccosum (teleomorph = Hypocrea sp., Thailand), T. vermipile (Republic of South Africa).

Last Modified: 10/26/2014
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