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ARS Home » Research » Publications at this Location » Publication #120449


item Samuels, Gary

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fungi in the genus Hypocrea, often as their Trichoderma asexual states, are useful in the biological control of plant diseases. The active ingredient in a commercial product that controls many disease-causing fungi is known only as the asexual Trichoderma fungus. Development of an improved product is hindered by the lack of a sexual state. A new species of Hypocrea was discovered in Indiana that is the sexual state of Trichoderma (Gliocladium) virens, the commonly used biocontrol fungus. In this paper the previously unknown sexual species, H. virens, is described and illustrated. The connection to the asexual T. virens is proven using both morphological and molecular characteristics. This work will be used by plant pathologists who are working to develop more effective strains that can be used in the biological control of plant diseases.

Technical Abstract: The new species Hypocrea virens, has been found to be the teleomorph of Trichoderma virens, a species commonly used in biological control applications. This conclusion is based on the comparison of morphological and molecular data from four isolates of T. virens and a single collection and isolate of H. virens. Data for several morphological characters, including colony and growth characteristics, were collected. In addition, sequence data from ITS1, 5.8S, ITS2 rDNA and translation elongation factor (tef-1à) were analyzed for the five isolates. Analysis of phenotypic characters show that cultures and microscopic characters of the anamorph of H. virens are indistinguishable from those of T. virens. This is consistent with sequence data from ITS1, 5.8S, ITS2 rDNA which show that the sequence of H. virens is identical to that of the ex-type isolate of T. virens. On the other hand, tef-1à sequences show a higher variation among all T. virens isolates with no non-synonymous substitutions. Trichoderma virens isolates and H. virens form a monophyletic group that is different from other examined species of Hypocrea; this clade is supported by a 100% bootstrap value. Molecular and morphological data confirm the connection between H. virens and T. virens.