Submitted to: Oklahoma Academy of Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2000
Publication Date: 1/24/2001
Citation: RUSH, L., KING, R., RUSSO, V.M., BILES, C., CLUCK, T. VEGETATIVE COMPATIBILITY AMONG NITRATE NON-UTILIZING (NIT) MUTANTS OF FUSARIUM OXYSPORUM. OKLAHOMA ACADEMY OF SCIENCE PROCEEDINGS. 2001. 81:90.
Technical Abstract: Eight Oklahoma isolates of Fusarium oxysporum were cultured on two types of agar amended with 1.5% potassium chlorate which is growth-restrictive for the wild-phenotype. Mutants were identified as fast growing mycelial sectors. Samples of all fast-growing sectors were transferred to a minimal agar medium. Nitrate non-utilizing mutants (Nit) were classified into 3 distinct groups based on the growth, or lack of growth, on minimal media amended with five different nitrogen sources. The phenotypic classes observed presumably reflected mutations at different loci in the nitrate reductase pathway. The three types of mutations were classified phenotypically as Nit-1, Nit-3, and Nit-M. Of the 86 Nit mutants, the majority were obtained from potato dextrose agar amended with chlorate (76%). Only 24% of the Nit mutants were obtained on a minimal media with chlorate. Fifty-three percent of the Nit mutants were Nit-1, 32.5% were Nit-3, and 14% were Nit-M. The mutation involving the molybdenum cofactor loci (Nit-M) occurred less frequently than either Nit-1 or Nit-3. Heterokaryon formation (complementation) was observed among mutants of different phenotypes from the same parental isolate and was highest (70% complementation) when Nit-M and Nit-1 were paired. Complementation among mutants of different phenotypes from different parental isolates occurred 56% of the time when pairing Nit-M and Nit-3 mutants, and 30% of the time when pairing Nit-M and Nit-1 mutants. Further analysis is ongoing to determine relatedness of F. oxysporum isolates based on vegetative compatibility.