<abstract xmlns="http://www.w3.org/1999/xhtml"><p> Fifteen species of Fagaceae from Chiang Mai province, northern Thailand, were investigated: eight Castanopsis, four Lithocarpus and three Quercus species. The species were generally diploid with the chromosome number 2n = 24, and the basic number x =12 was confirmed in some species with meiosis. One tree belonging to Q. lenticellatus had 2n = 14. Chromosomal mapping of the highly repetitive 18S-25S and 5S ribosomal genes by fluorescence in situ hybridisation (FISH) was performed. Most species (from all three genera) showed four 18S-25S rDNA sites (two pairs: one subterminal major and one paracentromeric/intercalary minor loci) and two 5S rDNA sites (one pair: paracentromeric locus). Quercus kerrii also had two pairs of 18S-25S rDNA sites, but both were subterminal major loci. Two species, C. argentea and Q. brandisianus, only had one pair of 18S-25S rDNA sites. Two species, C. calathiformis and L. vestitus, showed an odd number of (unpaired) sites, and this indicated hybrid origin and/or polyploidy. Polyploid cells were detected in these species. The ribosomal gene maps based on both sequences together were genus-specific. In Castanopsis, the 18S-25S and the 5S genes were localized on three different chromosome pairs, and comprised species-specific maps. On the other hand, the ribosomal genes in Lithocarpus and Quercus were found only on two chromosome pairs, because one of the two 18S-25S rDNA loci was localized on the same chromosome as the 5S rDNA locus. The FISH markers may be used to clarify discrepancies arising from morphological assessments.</p></abstract>

Fifteen species of Fagaceae from Chiang Mai province, northern Thailand, were investigated: eight Castanopsis, four Lithocarpus and three Quercus species. The species were generally diploid with the chromosome number 2n = 24, and the basic number x =12 was confirmed in some species with meiosis. One tree belonging to Q. lenticellatus had 2n = 14. Chromosomal mapping of the highly repetitive 18S-25S and 5S ribosomal genes by fluorescence in situ hybridisation (FISH) was performed. Most species (from all three genera) showed four 18S-25S rDNA sites (two pairs: one subterminal major and one paracentromeric/intercalary minor loci) and two 5S rDNA sites (one pair: paracentromeric locus). Quercus kerrii also had two pairs of 18S-25S rDNA sites, but both were subterminal major loci. Two species, C. argentea and Q. brandisianus, only had one pair of 18S-25S rDNA sites. Two species, C. calathiformis and L. vestitus, showed an odd number of (unpaired) sites, and this indicated hybrid origin and/or polyploidy. Polyploid cells were detected in these species. The ribosomal gene maps based on both sequences together were genus-specific. In Castanopsis, the 18S-25S and the 5S genes were localized on three different chromosome pairs, and comprised species-specific maps. On the other hand, the ribosomal genes in Lithocarpus and Quercus were found only on two chromosome pairs, because one of the two 18S-25S rDNA loci was localized on the same chromosome as the 5S rDNA locus. The FISH markers may be used to clarify discrepancies arising from morphological assessments.

Chromosomal Mapping of 18S-25S and 5S Ribosomal Genes on 15 Species of Fagaceae From Northern Thailand

Silvae Genetica

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Fifteen species of Fagaceae from Chiang Mai province, northern Thailand, were investigated: eight Castanopsis, four Lithocarpus and three Quercus species. The...

Chromosomal Mapping of 18S-25S and 5S Ribosomal Genes on 15 Species of Fagaceae From Northern Thailand

Published Online: Oct 14, 2017

Page range: 5 - 13

Received: Jul 05, 2006

DOI: https://doi.org/10.1515/sg-2008-0002

Keywords
Fagaceae, Castanopsis, Lithocarpus, Quercus, fluorescence in situ hybridisation (FISH), ribosomal gene mapping, 18S-25S and 5S rRNA genes

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Chromosomal Mapping of 18S-25S and 5S Ribosomal Genes on 15 Species of Fagaceae From Northern Thailand

Published Online: Oct 14, 2017

Page range: 5 - 13

Received: Jul 05, 2006

DOI: https://doi.org/10.1515/sg-2008-0002

KeywordsFagaceae, Castanopsis, Lithocarpus, Quercus, fluorescence in situ hybridisation (FISH), ribosomal gene mapping, 18S-25S and 5S rRNA genes

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Keywords
Fagaceae, Castanopsis, Lithocarpus, Quercus, fluorescence in situ hybridisation (FISH), ribosomal gene mapping, 18S-25S and 5S rRNA genes