Nuclear DNA content of benomyl-induced segregants of diploid strains of the phytopathogenic fungus Armillaria mellea

Abstract

The relative nuclear DNA contents of haploid, diploid, and benomyl-induced segregants of diploid strains of the phytopathogenic fungus Armillaria mellea were measured by mithramycin staining and fluorescence photometry. The diploid strains, originally recovered from sexually compatible matings of haploid strains, were heterozygous at mating-type and auxotrophic marker loci. The somatic segregants examined here were derived by treatment of the diploid strains with the fungicide benomyl in previous studies. As expected, the diploid strains had approximately twice as much nuclear DNA as the haploid strains. Most segregants had near-haploid DNA contents and no detectable heterozygosity at the marker loci; these strains were most likely true haploids. Other segregants with near-haploid DNA contents were heterozygous at a marker locus indicating that they were aneuploid. A minority of segregants had near-diploid DNA contents and may have been either aneuploid or diploid.Key words: basidiomycetes, mithramycin, parasexuality.

Genetic Evidence for Somatic Haploidization in Developing Fruit Bodies of Armillaria tabescens

“…In basidiomycetes investigated as to their parasexual recombination, the mechanism of haploidization is usually through aneuploidy. Diploid nuclei of Armillaria are very stable (Anderson and Ullrich, 1982), but somatic haploidization can be induced chemically with the aid of benomyl; also in this case haploidization probably proceeds through loss of chromosomes instead of a meiosislike mechanism (Anderson, 1983;Anderson and Yacoob, 1984;Anderson et al, 1985). According to the cytological observations of Tommerup and Broadbent (1975), the dikaryotic hyphae in Armillaria fruit bodies initiate from multinucleate terminal cells found in small fruit-body initials at the site of origin of the gills.…”

Identification of Kenyan Armillaria isolates by cultural morphology, intersterility tests and analysis of isozyme profiles

“…However, Armillaria does not fruit easily in culture. ANDERSON (1983) could obtain benomyl segregants by treating diploid isolates with benomyl, most of which were found to have near haploid DNA (ANDERSON et al 1984).…”

Parasexual analysis of common-A crosses in the basidiomycete Agrocybe aegerita

“…Radial growth of A. aegerita mycelium cannot be totally inhibited by saturated concentrations of benomyl in CM, and although benomyl acts directly on tubulin in lower fungi (Burland and Gull 1984), this has not yet been demonstrated in all fungi. Benomyl has been used to recover recombinants from Armillaria mellea diploids (Anderson 1983), most of which were aneuploids or true haploids (Anderson et al 1985). However, thiabendazole, a related molecule, lead to the recovery of diploid segregants from diploids of Ustilago violacea (Garber et al 1987).…”