Different karyotype patterns among allopatric Pinus nigra (Pinaceae) populations revealed by molecular cytogenetics

Abstract

To examine variation and taxonomic recognition of Pinus nigra (European black pine) at the intraspecific level, chromosomal distribution of 5S and 18S-5.8S-26S rDNA loci revealed by fluorescent in situ hybridisation (FISH) and fluorochrome banding with chromomycin A(3) and DAPI were analysed among allopatric populations belonging to different subspecies. Despite prevalent opinion on predominantly conserved and homogenous conifer karyotypes, several patterns were observed. Surprisingly, interstitial 18S rDNA loci and DAPI heterochromatin staining after FISH showed variations in distribution and localisation. Three subspecies shared a pattern with nine 18S rDNA loci (ssp. nigra, pallasiana and laricio) while ssp. dalmatica and salzmannii had eight rDNA loci. DAPI banding displayed two patterns, one with a high number of signals (ssp. nigra, pallasiana and dalmatica) and the other with a lower number of signals (ssp. salzmannii and laricio). We conclude that our results cannot provide proof for either classification scheme for the P. nigra complex, but rather demonstrate the variability of different heterochromatin fractions at the intraspecific level.

Molecular cytogenetic studies in western Mediterranean Juniperus (Cupressaceae): a constant model of GC-rich chromosomal regions and rDNA loci with evidences for paleopolyploidy

“…Regarding symmetry, the present results agree not only with the aforementioned previous ones on Juniperus, but with the general pattern in gymnosperms, which exhibit symmetrical karyotypes with mostly metacentric and some submetacentric chromosomes (Bogunić et al 2011, and references therein).…”

“…These signals are colocalised with CMA+ bands, indicating that 35S rRNA genes are located in GC-rich regions, as stated for many other gymnosperm genera (Bogunić et al 2011, and references therein). This rDNA model almost absolutely agrees with the one of previously studied Asian Juniperus taxa (Nagano et al 2007).…”

“…This pattern differs from those described in other gymnosperm genera both by the constancy and the scarcity of CMA+ bands. From four to 26 bands have been reported in several genera, such as Abies, Cedrus, Larix, Picea and Pinus, the number varying among taxa (Hizume et al 1994;Bou Dagher-Kharrat et al 2001;Siljak-Yakovlev et al 2002;Puizina et al 2008;Bogunić et al 2011). GC-rich regions have also been reported in SC, though not only there, in Picea (Siljak-Yakovlev et al 2002).…”

Intra- and interspecific karyotypic variations of the genus Senna Mill. (Fabaceae, Caesalpinioideae)

“…Among the 10 species analyzed, only three (S. alata, S. obtusifolia, and S. siamea) had previously been examined in terms of their CMA/DAPI banding patterns (Souza & BenkoIseppon 2004 (Dematteis et al 2006), Capsicum (Scaldaferro et al 2012), Allium pulchellum (Vosa 1996), and Pinus nigra (Bogunić et al 2011). Variations in heterochromatin bands between individuals of the same species appear to be an intraspecific cytological characteristic of the genus Senna that is worthy of further investigation, calling for the analysis of distinct populations from different ecosystems and different geographic regions.…”

A Comparative Analysis of Multi-Probe Fluorescence <i>In Situ</i> Hybridisation (FISH) Karyotypes in 26 <i>Pinus</i> Species (Pinaceae)

“…Data on banding patterns can be used for comparative karyotyping in some species, and they detect inter-and intraspecific variation patterns (Hizume et al 1983(Hizume et al , 1989(Hizume et al , 1990; however, fluorescent banding does not provide sufficient information for the discrimination of all homologous chromosome pairs. Not all homologous pairs in Pinus species were identified by probe signals in studies of karyotypes by FISH that used 35S rDNA and 5S rDNA probes (Doudrick et al 1995, Liu et al 2003, Cai et al 2006, Bogunić et al 2011, telomere sequences (Fuchs et al 1995, Shibata et al 2005, Islam-Faridi et al 2007, or simple sequence repeats (SSR) (Pavia et al 2014). Combined fluorescent banding and FISH investigations have identified interstitial and proximal CMA bands that are consistent with 35S rDNA and/or the short repetitive sequence proximal CMA band-specific repeat (PCSR) loci, and interstitial DAPI bands that are consistent with signals of repetitive sequences containing the Arabidopsis-type telomere sequence (Hizume et al 2001, Shibata et al 2005.…”