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ARS Home » Research » Publications at this Location » Publication #65752
Title: ISOZYME SUBGROUPS IN TRICHODERMA SECTION LONGIBRACHIATUM

Author
item LEUCHTMANN, ADRIAN - GEOBOTANY INST. SWITZ.
item PETRINI, ORLANDO - SWITZERLAND
item Samuels, Gary

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fungi are useful in the production of industrial enzymes because they grow rapidly and can be screened for strains that produce high levels of the desired enzyme. Such a fungus, Trichoderma reesei, produces cellulase that breaks down cellulose into simple sugars so that waste products such as sugarcane bagasse and pulp paper residues can be fed to animals. This fungus reproduces itself without undergoing sex but is related to fungi that reproduce sexually. By determining how closely related the cellulase-producing fungus is to the sexually reproducing fungus, it may be possible to develop a better cellulase-producing fungus using conventional genetic means. Using isozyme characteristics of this strain and strains of related fungi, that relationship has been determined. Based on the results of this paper, it may be possible to locate fungi in nature that produce even higher levels of cellulase to breakdown cellulose for industrial purposes.

Technical Abstract: Seventy-eight representatives of Trichoderma sect. Longibrachiatum, Hypocrea jecorina, and H. schweinitzii were compared using ten enzyme systems. The results essentially supported Bissett's morphologically based taxonomy of Trichoderma sect. Longibrachiatum, in that the species T. longibrachiatum, T. citrinoviride, T. parceramosum, and T. pseudokoningii could be distinguished. Trichoderma reesei was closely related to H. jecorina and more distantly linked to T. longibrachiatum, thus the synonymy of T. reesei with T. longibrachiatum was not supported. The possibility that T. reesei is a clonal derivative of H. jecorina is discussed. Strains of Trichoderma citrinoviride were intermingled with Northern Hemisphere strains of H. schweinitzii, suggesting it is the anamorph of that holomorph. Trichoderma pseudokoningii, the type of which was originally derived from ascospores of an Australian collection of H. schweinitzii, clustered with some New Zealand collections of H. schweinitzii, but independently of Northern Hemisphere H. schweinitzii. Trichoderma pseudokoningii may be rare outside of Australasia. No teleomorph could be linked either to T. longibrachiatum or T. parceramosum. Four collections of H. schweinitzii from New Zealand (3) and the Andean region of Venezuela formed a discrete group within the subcluster that included H. jecorina and H. schweinitzii. There was great homogeneity among strains of H. jecorina from a narrow equatorial band, suggesting continuing gene flow over distjunt regions.