Loss of avirulence and reduced pathogenicity of a gamma-irradiated mutant of Fusarium oxysporum f. sp. lycopersici

Jurriaan J. Mes*, Robbert Wit, Christa S. Testerink, Francis De Groot, Michel A. Haring, Ben J.C. Cornelissen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

23 Citations (Scopus)


The tomato Fusarium resistance gene 1-2 confers resistance to F. oxysporum f. sp. lycopersici race 2, which expresses the corresponding avirulence gene avrl-2. To elucidate the molecular basis of this gene-for-gene interaction, we initiated a search for the avrl-2 gene. Gamma irradiation mutagenesis, using 137Cs, was performed to generate an avrI-2 mutant of E oxysporum f. sp. lycopersici. To this end, a race 2 isolate was first transformed with a phleomycine resistance gene and a GUS marker gene in order to distinguish mutants from contaminating isolates. A total of 21,712 mutagenized colonies was tested for loss of avirulence on I-2-containing tomato seedlings. One mutant was selected that showed the expected loss of avirulence but, surprisingly, also showed reduced pathogenicity toward susceptible tomato plants. DNA analysis was subsequently used to visualize genomic changes in the mutant. Southern analysis on contour-clamped homogeneous electrophoretic field blots demonstrated a translocation of a 3.75-Mb chromosome in the mutant. Random amplified polymorphic DNA and amplified fragment length polymorphism analysis identified at least nine polymorphisms between the wild-type and mutant isolates. Most of these polymorphisms appeared as extra fragments in the mutant and contained repetitive DNA sequences.

Original languageEnglish
Pages (from-to)1131-1137
Number of pages7
Issue number12
Publication statusPublished - Dec 1999

Fingerprint Dive into the research topics of 'Loss of avirulence and reduced pathogenicity of a gamma-irradiated mutant of Fusarium oxysporum f. sp. lycopersici'. Together they form a unique fingerprint.

  • Cite this