The incompatibility system and relative ectomycorrhizal performance of monokaryons and reconstituted dikaryons of Laccaria bicolor

Abstract

The incompatibility system of four Laccaria bicolor collections was studied and found to be bifactorial with multiallelic mating type factors. One of the collections studied was a biological species of L. bicolor that was intersterile, but morphologically identical, with the others. Seedling growth parameters and ectomycorrhiza formation were measured after inoculation with (i) four sibling mating type monokaryons of a collection from Canada and from Sweden; (ii) four dikaryons formed by crossing the two compatible mating type pairs within each of these collections; and (iii) 16 dikaryons formed by crossing each mating type monokaryon from Canada and Sweden in all possible combinations. Each seedling growth parameter showed significant differences resulting from inoculation with different cultures. Ectomycorrhizal formation was also different depending on the culture used as inoculum. Possibilities for using the differences among cultures in studies of the genetics, physiology, and morphogenesis of the ectomycorrhizal symbiosis are discussed. The possibility of creating improved strains of ectomycorrhizal fungi for use in forest management is also discussed.