Mycosystema. 1991, 10(Z1): 1-14.
GC contents of the DNA of 60 isolates belonging to 40 species, 16 genera, 6 families of the Mucorales were investigated systematically. DNA extraction gave highly polymeric DNAs of good quality. After heat denaturation, a hyperchromicity of more than 35% was obtained. The GC content of different species was relatively constant. According to their average GC contents, the 16 genera of the Mucorales fell into 3 distinct groups: Gongronella, Haplosporangium, Mortierella, and Syncephalastrum belonging to the group with highest value, Cunninghamella belonging to the one with lowest value, while the other genera including Absidia, Mucor, Rhizopus, etc. gave GC values in between. The GC contents of these three groups range from 46.0 to 49.8%, 28.8%, and 34.9 to 41.9%, respectively. This agrees with the literature except that the GC contents of Helicostylum and Circinella are lower than reported. The differences of GC values within a single genus and a single species were generally less than 10% and 2% respectively. The GC values furnish more evidences to confirm the taxonomic position of Syncephalastrum monosporum Zheng et al. and Mortierella ramanniana (Moeller) Linnemann. Possible causes for the inconsistencies of some of the GC contents found in the present work and other works are discussed.
