Genetic variability of the wild incompatibility alleles of the tetrapolar basidiomycete Agrocybe aegerita

Abstract

The variability of the sexual incompatibility genes of Agrocybe aegerita was investigated in the homokaryotic progeny of 13 wild dikaryotic strains from five distinct European geographic origins. Results of mating tests allowed identification of 18 A alleles and 16 B alleles out of a possible 26 different alleles for each in the sample. The determination and the comparison by a contingency χ (2) test of the frequencies of allele replications between intra- and interregional matings showed no departure from a random distribution of incompatibility alleles. The allelic series estimated for the incompatibility genes of the entire population of A. aegerita, 30 A and 25 B aleles, are significantly less extensive than those already hypothesized for other tetrapolar hymenomycetes. However, the low variability of incompatibility genes has little effect on the outbreeding efficiency (92.6%) of this mushroom. The low variability of the incompatibility alleles and the apparent absence of intrafactorial recombination could relate to a single-locus structure of the incompatibility genes in A. aegerita.

Evidence for Limited Intercontinental Gene Flow in the Cosmopolitan Mushroom, Schizophyllum commune

“…In addition, Raper et al (1958) showed that pairs of fungal isolates collected from geographically distant collections were as likely to share alleles at a mating locus as pairs taken from the same locale. The mating allele distributions of several other mushroom species, such as Sistotrema brinkmannii (Ullrich and Raper 1974), Fomes cajanderi (Neuhauser and Gilbertson 1971), Pleurotus pulmonarius (Bresinsky et al 1987), Agrocybe aegerita (Noel et al 1991), and Panellus stypticus (Peterson and Bermudes 1992), have similarly demonstrated no apparent correlation with geography or climate. The major conclusion from these analyses of mating factors is that long distance gene flow is commonplace, and that these broadly distributed species may even be panmictic over their geographic range.…”

Genetic evidence for nonrandom sorting of mitochondria in the basidiomycete Agrocybe aegerita

“…Dikaryotic mycelia were cultivated in vitro to obtain basidiocarps from which basidiospores, which germinated to produce homokaryotic progeny, were isolated (10). Mating type alleles were identified as previously described (19).…”

Transcription of naked double-stranded RNA molecules in a fraction containing large vesicles plus mitochondria from the basidiomycete Agrocybe aegerita

“…The wild dikaryotic strains used, SM47 (mating-type alleles: A7A8 B4BQ and SM51 (A3A4 B3B4), were derived from in vitro cultures of fragments of fruiting bodies collected from nature. The dikaryotic strain SM47 was cultivated in vitro to obtain basidiocarps from which homokaryotic progeny A1 was obtained (Noel et al, 1991). The two strains SM51 and A1 were shown to lack dsRNA molecules and, accordingly, were used as controls in the RNA polymerase assays.…”