Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: ANALYSIS OF THE SPRUCE GENOME BY FLUORESCENCE IN SITU
HYBRIDIZATION
ANALYSIS OF THE SPRUCE GENOME BY FLUORESCENCE IN SITU
HYBRIDIZATION.
Garth R. Brown, Vindhya Amarasinghe and John E. Carlson.
Biotechnology Laboratory and Department of Forest Sciences,
University of British Columbia, Vancouver, B.C., Canada
In situ hybridization has made significant contributions
towards the understanding of the mammalian genome but has yet to
be fully exploited in plant genome analysis. In our
investigations of the spruce (Picea) genome, we have developed an
effective fluorescence in situ hybridization (FISH) procedure,
using DNA probes directly labeled with fluorochromes and confocal
microscopy, to physically map repetitive DNAs on metaphase
chromosomes. The aims of our research include deriving a
FISH-based karyotype for white spruce, gaining insight into
chromosome organization and evolution in spruce and ultimately,
single copy gene mapping. One of the repetitive DNAs we have
characterized is a 142 hp element tandemly arrayed in the spruce
genome. An estimated 20,000 copies are present in white spruce
(2n = 24), distributed at the centromeres of four homologous
chromosome pairs. Interestingly, in a closely related species,
Sitka spruce, five chromosome pairs contain this centromeric
element. At least three of these pairs do not correspond to the
homeologous white spruce chromosomes suggesting a redistribution
of this sequence during speciation. Results with additional
repetitive DNAs and progress towards a molecular karyotype of
white spruce will also be presented.
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