New insights into the Taxus baccata L. karyotype based on conventional and molecular cytogenetic analyses
2017
Tomasino, Maria Paola | Gennaro, Andrea | Simeone, Marco Cosimo | Schirone, Bartolomeo | Ceoloni, Carla
Scientific interest in the genus Taxus has recently increased worldwide, for both conservation and biotechnological purposes. In contrast with abundant studies on other gymnosperms, basic cytogenetic information on this genus is still very limited, likely due to difficulties in appropriate tissue handling and lack of efficient procedures for chromosome analyses. In the present study, chromosome pre-treatment protocols were established, and karyotype analyses successfully performed on meristematic tissue of root-tips derived from plant cuttings of English yew (Taxus baccata L.). Twelve homologous pairs were identified, including seven metacentric and five sub-metacentric chromosomes. No heteromorphic sex chromosomes were found. Multicolour fluorescence in situ hybridization (FISH) was successfully applied using the 18S and 5S rDNA probe sequences. Loci of both sequences turned out to be located on the same sub-metacentric chromosome pair. Microsatellite (simple sequence repeat) sequences were also successfully tested with a non-denaturing (ND)-FISH methodology, and their presence and distribution along yew chromosomes was highlighted. The results obtained provide new opportunities for an in-depth characterization of the Taxus genome, which can have potential positive outcomes for conservation and exploitation of the species, and also contribute to widen knowledge of gymnosperm genome structure and evolution.
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