INTERFERTILITY STUDIES IN TREMELLA MESENTERICA.

摘要

Tremella mesenterica, a saprobic heterobasidiomycete, somatically exhibits a yeast-mycelial dimorphism; producing a yeast stage in single spore culture and dikaryotic mycelium when compatible yeast strains are crossed. Interstock crosses of 46 collections demonstrated a modified bifactorial incompatibility system in which only two A factors and multiple B factors were observed. A total of 68 B factors were identified in this study. Anomalous B factors were observed in four stocks, but the origin of these factors is not believed to be from intrafactor recombination. A common characteristic shared by these four stocks is the abnormal morphology of all monokaryotic yeast strains. These abnormal strains often contain many hypertropic dead cells. Living cells were irregular in shape and often produced hyphae, whereas normal strains produced only budding ellipsoid to broad ellipsoid, yeast cells. A model is postulated which explains why anomalous B factors are found only in basidiocarps that produce morphologically abnormal progeny.;The specimens of T. mesenterica used in this study were obtained from Europe and North America, and were found on a variety of hardwoods. In addition to intra- and interstock crosses, macro- and microscopic examinations were made of these specimens. Although T. mesenterica was observed to be a morphologically, variable species, there are no morphologically distinct populations associated with substrate, or geographic distribution. Interstock crosses also did not demonstrate any intersterility groups associated with substrate, or with collection site. It is concluded that the variations observed in the morphological features of the basidiocarps are due to normal developmental changes, responses to different environmental conditions, and/or genetical differences that do not restrict interbreeding. Because of the macro- and microscopic variation exhibited by T. mesenterica, two taxa, T. lutescens and T. mesenterica, have been recognized by various authors. T. mesenterica has been selected as the correct epithet, and a neotype has been designated.