COMPARISON OF RIBOSOMAL DNA LENGTH AND RESTRICTION SITE POLYMORPHISMSIN GREMMENIELLA AND ASCOCALYX ISOLATES

The small subunit (SSU) and the internal transcribed spacer (ITS) of n uclear ribosomal DNA genes from 27 specimens of the fungal genera Grem meniella and Ascocalyx were amplified by PCR. Length polymorphisms wer e observed in the SSU and allowed the differentiation of four groups a mong the isolates tested: (i) Ascocalyx abietis; (ii) Gremmeniella iso lates from Picea spp.; (iii) Gremmeniella isolates from Abies balsamea ; and (iv) Gremmeniella isolates from Abies sacchalinensis, Larix spp. , and Pinus spp. The amplified ITS was the same length for all Gremmen iella specimens and was 60 bp longer in A. abietis. Phylogenetic analy sis of length polymorphisms and of 24 restriction sites in the SSU and ITS showed that Gremmeniella isolates were more related to each other than to the Ascocalyx isolate. Furthermore, seven groups were evident within the genus Gremmeniella. Our results confirm that Gremmeniella and Ascocalyx should be kept as different taxa and suggest that the ta xonomy of the former could be revised to consider isolates from Abies balsamea and from Picea spp. to be two different varieties while incor porating Gremmeniella laricina into G. abietina, as a new variety.