Analysis of the Polarity of the Jelly Basidiomycete Auricularia auricula

摘要

Auricularia auricula (L. ex Hook) Underw is an important jelly edible phragmo-basidiomycetidae, the polarity of which has long been disputed. In this study, double fluorescent staining of nuclei and septa was utilized to observe clamp connections in order to identify the dikaryotic mycelia. Some monokaryons and dikaryons derived from mating cultures were subjected to fruiting tests. All the results indicated that A. auricula exhibits bipolar heterothallism. It was interesting that some monokaryons belonging to parental mating-type (H_2 or J_3) were unable to cross when mating cultures occurred in the crossing combinations. In some mating combinations, dimorphic colonies occurred when mycelia from the region of conjunction were subcultured on to a fresh agar plates. Some mycelia in the dimorphic colony were dikaryotic, and the others were monokaryotic. There were nine combinations forming dimorphic colonies among a total 45 combinations in the fourth crossing group. If combinations with a characteristic dimorphic colony were designated as incompatible, the compatible mating ratio was 37.5%, far below the 50% compatibility ratio of a bipolar basidiomycete. The reasons leading to the dispute over the polarity of A. auricula are discussed. Slow nuclear migration and difficulty in judging monkaryon against dikaryon could result in the conclusion that A. auricula exhibited tetrapolar heterothallism. The barrier between pheromone and pheromone receptor is likely to cause slow nuclear migration and incompatibility between two different mating-type monkaryons.