1994 Volume 60 Issue 6 Pages 699-704
Nitrate-nonutilizing mutants (nit mutants) of 11 strains of Fusarium oxysporum from various formae speciales were formed on chlorate-containing media. The nit mutants were assigned to three phenotypic classes, nit1, nit3 and NitM, on the basis of their growth on media containing one of the following five different nitrogen sources; nitrate, nitrite, hypoxanthine, ammonium and uric acid. Frequency of nit mutation and proportion of three phenotypes in the obtained nit mutants depended on the strains of each forma specialis. Each strain of 8 formae speciales used was found to belong to different vegetative compatibility group from one another by vegetative compatibility test based on complementation reaction between nit mutants on the minimal medium. It is suggested that there is a possibility to use nit mutants as a marker in ecological studies of Fusarium diseases.
