The isolation of mutants affecting ascus development inNeurospora crassaand their analysis by a zygote complementation test

Abstract

A large number of mutants that affect the morphology of the ascus ofNeurospora crassahas been isolated by means of a screening technique that utilizes the filtration principle to separate colonial type mutants from wild type. In relationships with each other and with wild-type alleles, the mutant genes exhibit zygote dominance and recessiveness. A zygote complementation test for placing the recessive mutants into functional groupings is described. Results obtained by use of the test place the mutants into seven functional groups. Dominance relations in the developing ascus ofNeurosporaare discussed.