A cytological study of four Sicilian Serapias (Orchidaceae)

Cytological analysis of four Serapias L. (Orchidaceae), of which two are Sicilian endemics, is carried out. In particular, the endemic S. intermedia subsp. hyblaea shows a triploid chromosome complement with 2n = 3x = 54, representing natural nothotaxa arising from a hybridization process between supposed parental S. vomeracea (2n = 2x = 36) and Serapias lingua (2n = 4x = 72). For each of them the C-heterochromatin distribution, using Giemsa C-banding and karyotypes, was examined. The other endemic taxon (S. orientalis subsp. siciliensis) is characterized by a diploid chromosome number 2n = 2x = 36, of which the C-heterochromatin distribution is examined as well. The taxonomical relationships among these taxa are discussed in relation to the literature data

Advances in chromosomal studies in Neottieae (Orchidaceae): constitutive heterochromatin, chromosomal rearrangements and speciation.

Abstract — In this work, we describe a karyomorphological study on three taxa of the tribe Neottieae (Orchidaceae). Epipactis aspromontana and E. schubertiorum are characterized by a chromosome complement of 2n = 2× = 38. Significant differences in heterochromatin distribution were found between them. Similarities in the karyotype structure and C-banding of E. schubertiorum and E. helleborine group have been observed. A specimen of E. aspromontana showed a triploid chromosome number. The meiosis are characterized by univalent, bivalent and trivalent forms and in some somatic metaphase cells has been possible to observe a series of aneuploid numbers with 46, 47, 48, 49, 50, 51, 52 and 53 chromosomes. The largest differences can be emphasized between the Epipactis species and Neottia nidusavis, mainly in the the karyomorphology and heterochromatin distributions. In Neottia nidusavis the evolution process seems to be determined by reversing Robertsonian mutations

Cytotaxonomical considerations on Epipactis robatschiana (Orchidaceae), new species from Calabria (S Italy)

Abstract Epipactis robatschiana is a new species, described from Calabria (S Italy), where it grows in underwood of acidophilous pine-forests and beech-forests. This species is diploid with chromosome number 2n=2x=38. The karyotype is asymmetrical and consists of 4 large and 15 small chromosome pairs. C-banding patterns of this new species is quite similar to those of the other species of E. muelleri group, but it differs in the distribution of some heterochromatin bands. Its ecology and relationships with allied species are discussed too

Karyotype differentiation of four Cestrum species (Solanaceae) revealed by fluorescent chromosome banding and FISH

The karyotypes of four South American species of Cestrum (C. capsulare,C. corymbosum,C. laevigatum and C. megalophylum) were studied using conventional staining, C-CMA/DAPI chromosome banding and FISH with 45S and 5S rDNA probes. The karyotypes showed a chromosome number of 2n = 2x = 16, with metacentric chromosomes, except for the eighth submeta- to acrocentric pair. Several types of heterochromatin were detected, which varied in size, number, distribution and base composition. The C-CMA+ bands and 45S rDNA were located predominantly in terminal regions. The C-CMA + /DAPI + bands appeared in interstitial and terminal regions, and the C-DAPI + bands were found in all chromosome regions. The 5S rDNA sites were observed on the long arm of pair 8 in all species except C. capsulare, where they were found in the paracentromeric region of the long arm of pair 4. The differences in band patterns among the species studied here, along with data from other nine species reported in the literature, suggest that the bands are dispersed in an equilocal and non-equilocal manner and that structural rearrangements can be responsible for internal karyotype diversification. However, it is important to point out that the structural changes involving repetitive segments did not culminate in substantial changes in the general karyotype structure concerning chromosome size and morphology

Contribution to Karyomorphology of some species of the genus Quercus

In order to contribute to the knowledge of the taxonomic relationships between some species of the Quercus genus, the karyomorphology of 4 species (Quercus ilex L., Q, suber L., Q. robur L, and Q. pubescens WILLD.) was carried out. The somatic chromosome number 2n=24 was found in all taxa examined. An evident differentiation in karyotype structure of Q. ilex compared to other previous studied species has been found. Quercus suber, Q. robur and Q. pubescens possess moderately asymmetrical karyotypes. Q. suber differs from other species of the subgenus Cerris on the basis of karyological data showing similarities with Q, robur and Q. pubescens