Laccaria Bicolor

About the ectomycorrhizal basidiomycete Laccaria bicolor

The Life Cycle of L. bicolor (Maire) P.D. Orton

In L. bicolor, single meiospores germinate to produce haploid, monokaryotic mycelia. Two complex mating-type factors control sexual compatibility in the monokaryons and regulate the maintenance of the dikaryotic state. Fusion of sexually compatible haploid monokaryotic mycelia results in the formation of the dikaryotic mycelium. The hyphae of L. bicolor dikaryons develop clamp connections at each septum, while the hyphae of monokaryons do not. The dikaryon is the predominant vegetative structure in L. bicolor and most other basidiomycetes. Under appropriate conditions, the dikaryon produces the fruit bodies within which meiosis occurs. The monokaryotic and dikaryotic mycelia are capable of indefinite growth, allowing for the maintenance and duplication of the genotype of each ploidy state. The ectomycorrhizal symbiosis is generally induced by dikaryotic mycelia.

Laccaria bicolor S238N-H82: origin and culture conditions

A fruit body was collected in 1976 under Tsuga mertensiana in the Crater Lake National Park (Oregon, USA) by J Trappe & R Molina and deposited at the Forest Service (Corvallis). A subculture of this strain, so-called S238-O, was transferred to the INRA-Nancy in 1980 and renamed S238N. Spores were obtained from a sporophore collected under Pseudotsuga menziesii, inoculated with L. bicolor strain S238N in a glasshouse (Le Tacon et al. 1992) and germinated according to Fries (1983). Up to 100 different monokaryotic mycelia, including the H82 line, were stored and subcultured at INRA-Nancy.

For purification of the HMW DNA used for genomic library construction, the haploid monokaryotic line S238N-H82 was grown in petri dishes containing Pachlewski-agar medium and incubated at 25C.

The progenitor dikaryon, the component progenitor haploids, and the haploid monokaryotic line S238N-H82 were archived in duplicate in 1 ml of 15% glycerol at –80. The progenitor strains and all derivative strains are available upon request.

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