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HETEROCARYOSIS AND THE PARASEXUAL CYCLE IN ASPERGILLUS FUMIGATUS

1963; Oxford University Press; Volume: 48; Issue: 5 Linguagem: Inglês

10.1093/genetics/48.5.653

1943-2631

Ȗistein Strømnæs, E. D. Garber,

Fungal Biology and Applications

S>Twenty-seven haploid strains differing in color and nutritional requirements of the imperfect fungus Aspergillus fumigatus were involved in 51 heterocaryons. Color mutants were assigned to 12 loci; two allelic series, each with two mutants, were detected. The medium on which heterocaryons were grown and the combination of haploid strains appeared to determine the frequency of diploid conidia. Thirty-seven diploid strains were obtained and, of 36 strains, 25 were unstable in that they yielded haploid segregants. Aithough parental and certain recombinant genotypes usually occurred among haploid segregants from 17 diploid strains, the frequency of parental genotypes was generally lower than that of prototrophic recombinants. Twenty-three of 26 genetic markers could not be assigned to linkage groups. The absence of detectable linkages was attributed to nuclear selection of haploid segregants with certain genotypes in the haploid- diploid mycelium. Three alternate explanations were briefly discussed. A survey of published data on the frequency of haploid segregants from diploid strains of 11 taxa of filamentous fungi indicated that linkage was not detected in six taxa. (auth)