W artykule przedstawiono zwięźle historię badań systematycznych nad taksonami zaliczanymi do sekcji Phleum w rodzaju Phleum. Omówiono wyniki dotychczasowych badań cytotaksonomicznych w obrębie sekcji i ich znaczenie w badaniach nad filogenezą poszczególnych gatunków. Zaproponowano podział sekcji na 5 gatunków w oparciu o kryteria kariosystematyczne, uwzględniające strukturę kariotypu oraz ilość i lokalizację heterochromatyny w genomie. Przedyskutowano także kwestię pochodzenia gatunków poliploidalnych (P. commutation Gaud, i P. pratense L.).
Infraspecific variability of Avena fatua has been known from many results. In this paper were found differences in size and amount of stomata in 6 varieties of wild oat (fatua, alcaliphila, altissima, gravis, alta, vilis), among 9 studied. Var. fatua has the biggest stomata and their lowest amount, when var. vilis has the smallest ones and their highest amount. For 6 varieties (fatua, alcaliphila, levis, gravis, alta, vilis) has been found reversal dependence between size and amount of stomata.
Karyotype of conventionally stained and C-banded mitotic chromosomes of Rhoeo spathacea was analyzed. Chromosomes of this diploid species (2n = 12) were classified according to their meiotic sequence described by earlier authors. The chromosome complex of Rhoeo is comparatively rich in heterochromatin (~ 18% of karyotype length), and the main differences between C-banded chromosomes concern the amount of pericentromeric heterochromatin and the presence of distally located segments. It is suggested that the karyotype of R. spathacea presented here fulfills the criteria of Bennett’s "natural karyotype." C-banding of somatic interphase nuclei and mitotic prophases revealed a highly polarized arrangement of chromosomes (Rabl orientation). The centromeres have a distinct tendency to form rings within nuclei, and to gather into 1-3 large collective chromocenters. The presumptive role of non-random distribution of chromosomes at interphase is discussed.
The article presents a concise history of systematic studies on taxa included in the section Phleum of the genus Phleum. The authors discuss the results of cytotaxonomic studies within the section which have been conducted so far and their importance for studies of phylogeny of particular species. It is suggested that the section should be divided into five species on the basis of karyosystematic criteria considering the karyotype structure as well as localization of heterochromatin in the genome. The question of origin of two polyploid species (P. commutatum Gaud. and P. pratense L.) is also discussed.
Stomatal cell length was examined in four closely related taxa of sect. Phleum in the genus Phleum (P. nodosum, P. pratense and in two cytotypes of P. commutatum). It was found that the polyploid taxa (P. pratense, 2n = 6x = 42 and P. commutatum, 2n = 4x = 28) have longer stomatal cells than their diploid relatives (P. nodosum, 2n = 2x = 14 and P. commutatum, 2n = 2x = 14). In these two pairs of taxa, stomatal cell length can be a rapid and useful indirect ploidy level indicator and can assist in their identification. Material taken from live and dried specimens of a given taxon did not differ in stomatal cell length, meaning that different cytotypes can be identified from herbarium material as well.
The morphology of cell nuclei in callus obtained from root-tip meristems of Allium fistulosum L. (Monocotyledoneae, Alliaceae) was analysed. The most interesting phenomena observed in long-term callus culture were the different mechanisms of cell polyploidization, enlargement of telomeric segments of heterochromatin, and extensive chromatin elimination, associated with instability of nuclei size and DNA content. Protruding heterochromatin "spikes" were observed on the surface of some di- and polyploid nuclei. The presence of these spikes was connected with the formation of small heterochromatic micronuclei frequently found in the cytoplasm. It is suggested that these micronuclei are produced by direct elimination of heterochromatin from the interphase nuclei. Polyploid cells accumulated with each successive cell collection. The ploidy level attained by highly polyploid cells was 15C-220C. The shape of the nuclei and heterochromatin distribution suggest that polyploid nuclei in A. fistulosum tissue culture are produced by endoreduplication and by restitution cycles.