Abstract :
Tissue cultures of Gladiolus have been used successfully
to determine host specific properties of fusaric acid, a
phytotoxin produced by Fusarium oxysporum f. sp. gladioli
(Mas.) Sny. et Hn. Ten Gladiolus genotypes, including
three wild South African species, varying in resistance
to Fusarium-Tot. were differentiated based on the expressed
insensitivity to fusaric acid. Shoots and callus
cultures were challenged in vitro with various concentrations
of fusaric acid. The ion-release caused by the
toxin was measured with callus and intact cormels. In
all above mentioned bioassays resistant and susceptible
genotypes could be generally discriminated. However,
only two of the developed bioassays, the shoot assay
and the ion-release with intact cormels, gave significantly
coinciding results with the Fusarium-resistdncs assessed
in a greenhouse experiment. When using callus tissue in
the assays, the obtained answer correlated less with the
/"u.sflr(um-resistance. It is concluded Ihat a part of the
Fw5-ar/wm-resistance is based on fusaric acid insensitivity
