PAIRING TESTS TO DETERMINE MATING COMPATIBILITY IN PHELLINUS-WEIRII

Pairings of single-spore (Douglas-fir and western redcedar) isolates of Phellinus weirii from the same basidiocarp produce a wide variety of reactions, from formation of darkly pigmented barrage lines to no visible change in morphology. In contrast, pairings of single-spore isolates from different basidiocarps result in little or no line formation while heterokaryon-homokaryon (vegetative x single-spore isolate) pairings result in strong barrage line formation. Mating compatibility of any single-spore isolates may thus be determined by pairing the isolates, then back-pairing the interacted mycelium with a homokaryon from a different basidiocarp. If the initial pairing was compatible, a strong barrage line appears in the back-pairing. If the initial pairing was incompatible, no line appears. Using this method, it was determined that the genetic system governing mating compatibility in P. weirii is bipolar (governed by a single gene locus) and multiallelic.