CLASSIFICATION OF ISOLATES OF FUSARIUM OXYSPORUM F. SP. GLADIOLI ON THE BASIS OF PATHOGENICITY AND VEGETATIVE COMPATIBILITY

Fusarium ‘corm rot’ and ‘yellows disease’ of gladiolus are caused by Fusarium oxysporum f. sp. gladioli. This forma specialis is also held responsible for corm/bulb rot diseases in other genera within the Iridaceae. A collection of Fusarium isolates, most from gladiolus and some from other iridaceous plants, was characterized on the basis of pathogenicity to two different gladiolus cultivars (one ‘large-‘ and one ‘small-flowering’ cultivar) and on mutual vegetative-compatibility.
Two physiological races were recognized: Race 1 being pathogenic to both host genotypes and race 2 being pathogenic only to the ‘small-flowering’ cultivar.
We could distinguish three vegetative compatibility groups (VCGs). One VCG contained isolates of both races, the other two VCGs consisted only of race 2 isolates.

Wound inoculation of corm tissue from ‘large-flowering’ cultivars with race 2 resulted in the induction of a wound-response-like defence mechanism, including deposition of phenolic material in cell walls and periderm formation, restricting the fungus to the side of inoculation.
Race 1 also induced deposition of phenolics, but no periderm was formed and the fungus succeeded in colonizing the corm tissue by intercellular growth.

VI International Symposium on Flower Bulbs

E.J.A. Roebroeck, J.J. Mes

https://doi.org/10.17660/ActaHortic.1992.325.108