© 1993 Heron Publishing—Victoria, Canada
Restriction map and polymorphisms of nuclear ribosomal genes of Populus balsamifera
Michael U. Stoehr (1, 2, 3) and Rama S. Singh (1)
1. Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada / 2. Author to whom correspondence should be addressed / 3. Research Laboratory, Ministry of Forests, 1320 Glyn Road, Victoria, BC V8W 3E7, Canada / Received February 13, 1992
Summary
Balsam poplar (Populus balsamifera) clones from five populations, which were collected along a transect from northern Wisconsin to the northern tree line, were
evaluated for polymorphisms in nuclear ribosomal DNA. For this purpose, a restriction map was constructed using four six-cutter
enzymes in single and double digests of genomic DNA. After electrophoretic separation on agarose gels and Southern transfer,
blots were hybridized to non-radioactively labeled heterologous rDNA probes of soybean. Among populations, variation was detected
in the length of the intergenic spacer between the tandem repeats of the coding regions and in the degree of methylation of
one restriction enzyme recognition site. Based on a comparison of the derived restriction map of balsam poplar and other poplars,
high homology was evident in the rDNA coding regions among species, whereas the intergenic
spacer varied slightly in both length and number of restriction sites.
Keywords:
biochemical markers, genetic variation, ribosomal DNA, Southern transfer.
