MUTANTS OF NEUROSPORA-CRASSA THAT ALTER GENE-EXPRESSION AND CONIDIA DEVELOPMENT

Several genes have been identified that are highly expressed during co nidiation. Inactivation of these genes has no observable phenotypic ef fect. Transcripts of two such genes, con-6 and con-10, are normally ab sent from vegetative mycelia. To identify regulatory genes that affect con-6 and/or con-10 expression, strains were prepared in which the re gulatory regions For these genes were fused to a gene conferring hygro mycin resistance. Mutants were then selected that were resistant to th e drug during mycelial growth. Mutations in several of the isolates ha d trans effects; they activated transcription of the corresponding int act gene and, in most isolates, one or more of the other con genes. Mo st interestingly, resistant mutants were obtained that were defective at different stages of conidiation. One mutant conidiated under condit ions that do not permit conidiation in wild type.