A ROSE-BENGAL AMENDED MEDIUM FOR SELECTING NITRATE-METABOLISM MUTANTSFROM FUNGI

A rose bengal amended medium for selecting nitrate-metabolism mutants from fungi with reduced sensitivity to chlorate is described. Isolates of several species known to resist development of nitrate-metabolism mutants on chlorate medium formed such mutants when grown on the rose bengal chlorate medium. These species include Aspergillus flavus (Link .), Fusarium lateritium (Nees ex Link.), Fusarium oxysporum (Schlecht. ), Fusarium solani (Mart.) Sacc., Alternaria cassiae (Jurair and Khan) , Alternaria macrospora (Zimmerman), and Alternaria tagetica (Shome an d Mustafee). The medium allows selection of nitrate-metabolism mutants of certain fungal strains for which chlorate-based techniques have no t been satisfactory. Resulting mutants, following phenotype determinat ion and identification of complementary testers, can be paired to enab le macroscopic observation of heterokaryon formation during vegetative compatibility analyses. Thus, this medium may facilitate development of information on delimitation of vegetative compatibility groups amon g strains within these taxa.