GENETIC-CONTROL OF SOMATIC INCOMPATIBILITY IN THE ROOT-ROTTING BASIDIOMYCETE HETEROBASIDION-ANNOSUM

Heterokaryons of Heterobasidion annosum with known nuclear composition were constructed and paired in culture, and incompatibility reactions were rated. Heterokaryons with unrelated nuclear types, and heterokaryons with one common nuclear type and the second unrelated, were invariably somatically incompatible. Heterokaryons composed of one common nuclear type and the second nuclear type from basidiospores from a single basidiocarp gave from 0 to 21% compatible reactions when paired in all combinations. The results are consistent with a system of heterogenic somatic incompatibility with each nuclear type acting independently, and controlled at 3 or 4 loci, with at least one locus multiallelic.