engleski

Genome size and chromosome number in some Centaurea (Asteraceae) from Croatia

Croatian Adriatic coast and islands are unique and distinctive area, thanks to its general features, unusual relief features, climate, complicated geological history and the relatively good preservation. Five world areas characterized by a Mediterranean climate, makes 2% of the world area which manages 20% of all known plant species, European Mediterranean with 10% of all known species in only 1.6% of the world surface. The genus Centaurea is one of the largest in the Asteraceae family, containing at least 400 species (even 700). East Anatolia and Transcaucasia are the primary center of the origin and diversification of the genus Centaurea, while the Mediterranean area, including the Balkan Peninsula, is the second one. In Croatia 79 Centaurea taxa have been listed, comprising 27 endemic species. Our preliminary chemical and biological observations, of extracts and volatiles isolated from few endemic species from Centaurea taxa, from Adriatic region showed that there are differences in chemical composition of volatile as well as differences of biological activities between the same species found on different localities. In order to determine whether these differences were generated from different ecological conditions or because of different structure on genetic level, cytogenetic analysis of selected plant species of Centaurea taxa from Croatia were made. Cytogenetic analysis was performed on a sampling covering 28 populations of 9 different Centaurea species among which 4 endemic for Croatia or Croatia and Italy. These species belong to 7 different sections and present four different basic chromosome numbers, x=8, 9, 10 and 11. Two ploidy levels, diploid and tetraploid, were also detected. The nuclear DNA amounts (2C DNA), assessed by flow cytometry, range from 1.63 to 3.61 pg for diploid and to 6.86 pg when including tetraploid species. Intraspecific genome size polymorphism was observed among populations of five out of nine studied species: C. dalmatica, C. ragusina, C. rupestris, C. spinosociliata and C. salonitana. The genome of a tetraploid C. salonitana population was nearly twice that of the diploids. Dysploidy (changement of basic chromosome number) and polyploidy are observed as the main evolutionary mechanisms among studied representatives of the genus Centaurea in Croatia.

Centaurea ; flow cytometry ; genome size ; polyploidy

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