Genetic Analysis of a Mutant of Aspergillus Flavus Producing More Aflatoxin B₂ Than B₁

SUMMARY

Parasexual crosses involving a mutant of Aspergillus flavus having a high and relatively stable level of aflatoxin B₂ relative to aflatoxin B₁ have revealed a genetic locus for control of aflatoxin synthesis. Five different diploids, each heterozygous for high aflatoxin B₂ levels, accumulated low amounts of B₂ but high amounts of B₁. Although the haploid segregants from these diploids included a variety of aflatoxin phenotypes, one-half produced more B₁ than B₁ and one-half produced less B₂ than B₁. Five different diploids, each homozygous for high aflatoxin B₂ levels accumulated high amounts of B₂ as did all haploid segregants from these diploids. A single genetic locus is thought to control the higher aflatoxin B₂ than B₁ accumulation in this mutant.