Auxotrophic Mutants of Cochliobolus Carbonum

SUMMARY

Biochemical mutant strains of Cochliobolus carbonum were recovered following irradiation of conidia with ultraviolet light. Because of the multicellular, multinucleate condition of the spores and the methods of recovery that were employed, low yields of mutants were obtained.

Recovery of arginine, methionine, and adenine auxotrophs in highest frequency suggested that the methods of recovery were selective for these classes of mutants. Arginine and methionine mutants were classified into several physiological types, each type representing mutation at a different locus. Pathways for the synthesis of arginine and methionine established in other fungi were demonstrated in C. carbonum.

Genetic analyses of auxotrophs were hampered by infertility problems. While crosses between mutants and wild-type isolates were generally fertile, crosses between mutants were generally infertile.