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 application of chromosome banding methods for plant karyosystematic studies is analyzed. The authors discuss ways of constructing C-band idiograms and interpretating the results of C-banding studies with respect to the polymorphism of heterochromatin and its histochemical differentiation. The role of quantitative changes of heterochromatin in evolution, its functional effect, and the division into dispensable and indispensable heterochromatin are presented. An overview of the recent literature on this subject is also given.
We analysed chromosome lengths, karyotype structure, and nuclear DNA content (flow cytometry) in diploid (2n=20) and triploid (2n=30) European H. lupulus var. lupulus, American H. lupulus var. neomexicanus (2n=20) and Japanese ornamental hop, H. japonicus (F/2n=16; M/2n=17). Diploid female representatives of H. lupulus var. lupulus and H. l. var. neomexicanus differed in total length of the basal chromosome set (23.16 µm and 25.99 µm, respectively) and nuclear 2C DNA amount (5.598 pg and 6.064 pg) but showed similar karyotype structure. No deviation from the additivity, both in chromosome length and 2C DNA amount was evidenced in triploid monoecious H. lupulus (2n=30, XXY). H. japonicus showed different karyotype structure, smaller basal chromosome set (F/18.04 µm, M/20.66 µm) and lower nuclear DNA amount (F/3.208 pg and M/3.522 pg). There are first evaluations of nuclear genome size in diploid, not commercial representative of European H. lupulus var. lupulus and American H. lupulus var. neomexicanus and first attempt to determine the absolute male and female genome size in two Humulus species.
Chromosome numbers are given for the following species of Taraxacum sect. Palustria from Poland: T. paucilobum Hudziok (2n = 24, 25), T. belorussicum Val. N. Tikhom. (2n = 24), T. subdolum Kirschner & Štěpánek (2n = 24), T. udum Jordan (2n = 24), T. trilobifolium Hudziok (2n = 24), T. bavaricum Soest (2n = 24), T. portentosum Kirschner & Štěpánek (2n = 32), T. vindobonense Soest (2n = 32), and T. brandenburgicum Hudziok (2n = 32). The chromosome numbers of T. belorussicum and T. portentosum are published for the first time, and for T. subdolum, T. bavaricum and T. brandenburgicum for the first time from Poland. The analyzed group of taxa is heterogenous in respect of stomatal size, and after pooling of data the tetraploids show bigger stomata than the triploids.
The male-specific DNA markers are very useful in molecular sexing of non-flowering plants and seeds of dioecious species. In this paper we identified ten Y chromosome-specific RAPD primers suitable for identification of male plants in three Cannabaceae species with sex chromosomes (Humulus lupulus, XX/XY; H. japonicus, XX/ XY1Y2; Cannabis sativa, XX/XY). Basing on the nucleotide sequence of the OPJ-09 RAPD product we developed the HJY09 SCAR marker, which is very efficient in sexing of Japanese hop.
The morphology, karyotype structure and nuclear DNA amount of European and American representatives of alpine cat's-tail Phleum commutatum Gaud. were analysed. The evolutionary relationships within this group of taxa are discussed. It was shown that the American and European tetraploids are both morphologically and karyologically similar to each other and to the diploid race of this species from the Polish Carpathians. Diploid relatives of tetraploid P. commutatum i.e., P. commutatum (2x) and P. rhaeticum (Humphries) Rauschert, showed intra- and interspecific differences in nuclear 2C DNA values, whereas tetraploids (of both European and American origin) showed highly uniform nuclear DNA amounts. The 2C DNA uniformity and the greater mean size of the basal chromosome set in tetraploid P. commutatum as compared with its diploid relatives suggest that the change in genome size occurred during early evolution of the tetraploid race of P. commutatum, before its migration to America.
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