INHERITANCE OF THE ABILITY FOR ECTOMYCORRHIZAL COLONIZATION OF PINUS-STROBUS BY LACCARIA BICOLOR

Ectomycorrhizal colonization of Pinus strobus by monokaryotic and dika ryotic progeny of two strains of Laccaria bicolor was studied. The mon okaryotic progeny of one strain formed ectomycorrhizae with between 1. 5 and 80% of the available short roots. In the other case, the monokar yotic progeny formed ectomycorrhizae with between zero and 22% of the available roots. Percent ectomycorrhizal colonization by the dikaryoti c progeny of both strains was continuously distributed from 30 to 84% in one case and from zero to 80% in the other. The results indicate th at percent ectomycorrhizal colonization is polygenically controlled. A quantitative analysis of the dikaryotic progeny of one of the strains indicates that the degree of genetic determination, under the conditi ons of this study are 19.7 and 4.4%. The interactive genetic component accounted for most of the genetically determined variation in this st udy.