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Characterization of benomyl resistant mutants of Aspergillus nidulans

Nilce Maria Martinez-Rossi^I; João Lúcio Azevedo^II

^IDepartamento de Genética, Faculdade de Medicina de Ribeirão Preto, USP, 14049 Ribeirão Preto, SP. Brasil. Send correspondence to N.M.M.R.
^IIInstituto de Genética, ESALQ-USP, 13400 Piracicaba, SP, Brasil

ABSTRACT

Three colonies of Aspergillus nidulans, BEN-36, BEN-37, BEN-38, selected for resistance to thiophanate-methyl were also resistant to benomyl. The level of resistance to benomyl shown by these mutant strains was at least 45 and 4.5 times higher than those shown by the wild type strain and a known benomyl-resistant strain (FGSC 524), respectively. The resistance marker was due to mutation in a single gene at the benA locus. The dosage resistance curves of the heterozygous diploids to benomyl and thiophanate-methyl indicated that the benA36 and benA37 alleles are semi-dominants, and the benA38 allele is apparently fully dominant. Unexpectedly, the presence of benomyl or thiophanate methyl in the culture medium did not inhibit the conidiation of these mutants, a fact possibly indicating the presence of a second mutation responsible for this phenomenon.

Keywords: Benomyl; Resistant Mutants; Aspergillus Nidulans.

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