Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2001
Publication Date: 7/10/2002
Citation: Hanson, L.E., Howell, C.R. 2002. Biological control efficacy and other characteristics of protoplast fusants between trichoderma koningii and t. virens. Mycological Research. Interpretive Summary: One major limitation to the use of many organisms for biological control is the ability to store active forms of the organism at ambient temperatures. Since factors important for biocontrol in fungi such as Trichoderma virens are not fully understood, direct transfer of biocontrol activity into organisms that store well is not presently possible. The objective of this research was to make fusions between a strain of Trichoderma virens with good biological control activity and a strain of Trichoderma koningii with good storage qualities to combine the desirable qualities. Five fusants were obtained, three of which differed from the similar parental strain in control of cotton seedling damping-off caused by Rhizoctonia solani. One fusant had reduced activity. These fusants are useful for scientists to study factors important in biocontrol activity for ra year after storage at room temperature, while all of the other biocontro strains lost most or all of their activity after 6-8 months of storage. This strain should be useful to scientists in overcoming the storage limitations for biocontrol preparations of Trichoderma. Eventually, strains with even greater biocontrol and storage activity will be of use to growers in controlling seedling diseases.
Technical Abstract: Several Trichoderma (Gliocladium) virens strains have good biological control activity against rhizoctonia solani on cotton but lack some of the commercially desirable characteristics found in other Trichoderma species. In an attempt to combine these desirable characteristics, we used a highly effective biological control strain of T. virens in protoplas fusions with a strain of T. koningii, which had good storage qualities, but little biocontrol efficacy. All fusants were morphologically similar to one of the parental species. However, when compared to the morphologically similar T. koningii parent, two fusants showed significantly better biological control activity against R. solani on cotton. In addition, one T. virens-like fusant gave significantly less control than the T. virens parent. Fusants also differed from the morphologically similar parent in the production of secondary metabolites. One fusant was obtained dwhich maintained biological control activity during storage for up to a year.