*Dipartimento di Genetica, Chimica e Biologia Medica, Sezione di Biologia, Università di Torino, Via Santena 5 bis, 10126 Torino, Italy.
Stability of transformed antagonistic Fusarium oxysporum strains in vitro and in soil microcosms
Article first published online: 28 JUN 2008
Volume 5, Issue 5, pages 641–649, October 1996
How to Cite
MIGHELI, Q., FRIARD, O., TEDESCO, D. D., MUSSO, M. R. and GULLINO, M. L. (1996), Stability of transformed antagonistic Fusarium oxysporum strains in vitro and in soil microcosms. Molecular Ecology, 5: 641–649. doi: 10.1111/j.1365-294X.1996.tb00359.x
Quirico Migheli, Daniela Del Tedesco, M. Romana-Musso and M. Lodovica Gullino belong to the group of Angelo Garibaldi (University of Torino) and are involved in research aimed at the improvement of the activity of antagonistic Trichoderma and Fusarium spp. against foliar and soil-borne fungal pathogens and in risk assessment studies for the release of genetically manipulated and nonmanipulated antagonistic fungi in the environment. Olivier Friard is currently involved in the development of automated PCR-based diagnostic systems for detection of human viruses.
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- Received 3 January 1996 revised 21 April 1996
- antagonistic Fusarium oxysporum;
- biological control;
- genetic transformation;
- hygromycin B resistance;
- mitotic stability;
- Fusarium wilt of carnation
The stability of a genetically modified strain of Fusarium oxysporum used as antagonist against phytopathogenic formae speciales of F. oxysporum was evaluated both in vitro and in microcosm assays. The Escherichia coli hygromycin B phosphotransferase gene (hph), conferring hygromycin B resistance, was introduced by genetic transformation into a recipient strain marked by benomyl resistance and a dark red pigmentation. Hybridization with the complete plasmid suggested that the integration had generally occurred in a multiple-tandem array at multiple sites. Among nine independent transformants tested, only three of them were mitotically stable after four rounds of vegetative growth with no selective pressure, while six showed various changes in the integration pattern. One transformant had lost the ability to grow in the presence of hygromycin B. In soil microcosms all the transformants maintained the hygromycin B resistant phenotype, but six of them showed rearrangement of transforming DNA. Only one strain (coded T26.40) underwent no obvious rearrangement both after in vitro growth and after recovery from the soil microcosm. The nine transformants were used in three biological control experiments against Fusarium wilt of carnation in comparison to two untransformed reference strains and to the recipient mutant. A high degree of variability in the biocontrol activity was observed throughout the experiments and only transformant T26.40 consistently controlled the incidence of disease. The results are discussed in relation to risk assessment of the release of transgenic antagonistic fungi.