Immunofluorescence analysis of the microtubule cytoskeleton in the yeast phase of the basidiomycetes Kriegeria eriophori and Septobasidium carestianum

The microtubule cytoskeleton of the yeast phase of the heterobasidiomycetes Kriegeria eriophori and Septobasidium carestianum was investigated using immunofluorescence localization. Mitosis was typically basidiomycetous in both taxa with metaphase and part of anaphase occurring in the bud. Buds in K. eriophori were initiated while cortical cytoplasmic microtubules were present unlike the situation in ascomycetous yeasts. Kriegera eriophori showed a number of distinctive features, including the pattern of the interphase cortical microtubule array, the number of microtubules associated with the migrating nucleus, and the timing and degree of development of asters. Kriegeria eriophori showed consistently contorted anaphase B spindles, indicating that the spindle elongated faster than the poles separated and suggesting that it may be responsible for part of the motive force in spindle elongation. The value of the microtubule cytoskeleton as a source of characters for phylogenetic analysis of basidiomycetous yeasts and filamentous taxa is discussed.