Molecular cytogenetic analysis of Siberian Larix species by fluorescence in situ hybridization.

摘要

Karyotypes of three Larix species (L. sibirica, L. gmelinii, and L. cajanderi) were analyzed using fluorescence in situ hybridization (FISH) with 45S and 5S ribosomal RNA gene probes and 4',6-diamidino-2-phenylindole (DAPI) staining. Two major 45S ribosomal DNA (rDNA) loci (per haploid genome) have been observed in the intercalary regions of two metacentric chromosomes, III and IV, of L. sibirica; in addition to them, minor nucleolus organizing regions (NORs) were mapped in pericentromeric regions of chromosomes I, II, VI, and XII. Two closely related species, L. gmelinii and L. cajanderi, showed similar hybridization patterns; both species possessed an additional major locus of 45S rDNA in the distal region of the long arm of submetacentric chromosome VII that is absent in L. sibirica. Only one locus of the 5S rDNA was found in all larch species we studied; it was located in the distal region of the chromosome III short arm, which also carried the major NOR in the opposite arm. This chromosome containing major loci of the two ribosomal RNA gene families can serve as a marker of the genus Larix. The intra- and interspecific karyotype diversity in the genus Larix is discussed.Digital Object Identifier http://dx.doi.org/10.1007/s00606-012-0737-y