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Reference karyotype and cytomolecular map for loblolly pine (Pinus taeda L.)

Informally Refereed

Abstract

A reference karyotype is presented for loblolly pine (Pinus taeda L., subgenus Pinus , section Pinus, subsection Australes), based on fluorescent in situ hybridization (FISH), using 18s-28s rDNA, 5s rDNA, and Arabidopsis-type telomere repeat sequence (A-type TRS). Well separated somatic chromosomes were prepared from colchicine-treated root meristems, using an enzymatic digestion technique. Statistical analyses performed on chromosome-arm lengths, centromeric indices, and interstitial rDNA and telomeric positions were based on observations from 6 well-separated metaphase cells from each of 3 unrelated trees. Statistically, 7 of the 12 loblolly pine chromosomes could be distinguished by their relative lengths. Centromeric indices were unable to distinguish additional chromosomes. However, the position and relative strength of the rDNA and telomeric sites made it possible to uniquely identify all of the chromosomes, providing a reference karyotype for use in comparative genome analyses. A dichotomous key was developed to aid in the identification of loblolly pine chromosomes and their comparison to chromosomes of other Pinus spp. A cytomolecular map was developed using the interstitial 18s-28s rDNA and A-type TRS signals. A total of 54 bins were assigned, ranging from 3 to 5 bins per chromosome. This is the first report of a chromosome-anchored physical map for a conifer that includes a dichotomous key for accurate and consistent identification of the P. taeda chromosomes.

Keywords

FISH, loblolly pine, 18S-28S rDNA, A-type TRS, reference karyotype, cytomolecular map, dichtomous key, TRS/18-28S bins

Citation

Islam-faridi, M. Nurul; Nelson, C. Dana; Kubisiak, Thomas L. 2007. Reference karyotype and cytomolecular map for loblolly pine (Pinus taeda L.). Genome, Vol. 50: 241-251
https://www.fs.usda.gov/research/treesearch/27560