Induced alternative oxidase activity and attenuation of virulence in respiratory mutants of Fusarium oxysporum f. sp. basilicum and Collectotrichum coccodes.

摘要

Mitochondrial hypovirulence associated with cyanide-resistant alternative oxidase activity in the chestnut blight fungus offered unique insights to study both mitochondrial contributions to pathogenicity and the biological control of an important pathogen. Cyanide-resistant respiration was induced in two other fungal pathogens including Fusarium oxysporum f. sp. basilicum and Colletotrichum coccodes both serious pathogens of their respective hosts, basil and tomato. Twelve mutants isolated from F. oxysporum f. sp. basilicum had high levels of cyanide-resistant respiration accounting for 45% to 100% of total respiration and were significantly less virulent and grew slower than the wild type strain. One strain could transfer the abnormal respiratory phenotype and hypovirulence to the wild type strain. Attempts at biological control using respiratory mutants to control virulent strains showed little evidence of control. High levels of cyanide-resistant respiration was also induced in Colletotrichum coccodes. Cyanide-resistant respiration was correlated with reduced virulence, slow growth and abnormal colony morphology in at least one of the mutants isolated.