Recovery of mutants impaired in pathogenicity after transposition of Impala in Fusarium oxysporum f.sp. melonis

The ability of transposon impala to inactivate genes involved in pathogenicity was tested in Fusarium oxysporum f. sp. melonis. Somatic excision of an impala copy inserted in the nitrate reductase-encoding niaD gene was positively selected through a phenotypic assay based on the restoration of nitrate reductase activity. Independent excision events were analyzed molecularly and shown to carry reinsertedimpala in more than 70% of the cases. Mapping of reinserted impala elements on large NotI-restriction fragments showed that impala transposes randomly. By screening 746 revertants on plants, a high proportion (3.5%) of mutants impaired in their pathogenic potential was recovered. According t…

Determinism of the biocontrol capacity of a strain of Fusarium oxysporum: identification of genes expressed during interactions with tomato

Microbiological control of soil-borne phytopathogenic fungi with special emphasis on wilt-inducing Fusarium oxysporum

Contents   Summary  529 I. Biological control of plant diseases: state of the art  530 II. Main modes of action of biological control agents  530 III. The protective strains of F. oxysporum: an unexplored model  532 IV. Future directions for the study of the protective capacity of strains of F. oxysporum  539 V. How to make biological control successful in the field?  540   References  541 Summary Plant diseases induced by soil-borne plant pathogens are among the most difficult to control. In the absence of effective chemical control methods, there is renewed interest in biological control based on application of populations of antagonistic micro-organisms. In addition to Pseudomonas spp. a…

Recovery of Fusarium oxysporum Fo47 mutants affected in their biocontrol activity after transposition of the Fot1 element

Trouvelot, S., Olivain, C., Recorbet, G., Migheli, Q., and Alabouvette, C. 2002. Recovery of Fusarium oxysporum Fo47 mutants affected in their biocontrol activity after transposition of the Fot1 element. Phytopathology 92:936-945. To investigate the biocontrol mechanisms by which the antagonistic Fusarium oxysporum strain Fo47 is active against Fusarium wilt, a Fot1 transposon-mediated insertional mutagenesis approach was adopted to generate mutants affected in their antagonistic activity. Ninety strains in which an active Fot1 copy had transposed were identified with a phenotypic assay for excision and tested for their biocontrol activity against F. oxysporum f. sp. lini on flax in greenho…