Chromosomal studies on the alpine genus Dolomiaea

Chromosomal characteristics are important for our understanding of the evolutionary history of species diversification. However, these characteristics are as yet unknown for some plant genera, especially those in alpine regions. In this study, our aim was to investigate the chromosome numbers and karyotypes of Dolomiaea, an alpine genus occurring in the Qinghai-Tibet Plateau and adjacent regions, for the first time. We report the chromosome numbers and karyotypes of 10 species originally assigned to Dolomiaea, one species which has been suggested should be transferred to this genus and one species from the closely related genus Himalaiella. Two chromosome numbers, i.e. 2n = 36 and 2n = 34, were found in these 12 species. One B chromosome was observed in two species. Karyotypes of all the species examined are relatively asymmetrical, and are classified as Stebbins' types 3B and 2B. These findings suggest that polyploidization events played a minor role in species diversification in this alpine genus. Aneuploidy and karyotypic differentiation at the diploid level, instead, contributed greatly to species diversification in this genus. However, many lines of evidence indicate that the ancestor of the genus originated from an ancient polyploidization event. In addition, our results provide cytological evidences of the transference of Frolovia frolovii and Saussurea costus to Dolomiaea, a recent proposal based on molecular phylogenetic context

Pollen morphology of the genus Cota

Pollen morphology of 22 Cota taxa naturally distributed in Turkey was investigated to describe their pollen features and to evaluate the diagnostic value of pollen characters for systematic purposes using light microscopy and scanning electron microscopy. Pollen grains of Cota are radially symmetrical and isopolar. Their shape is oblate-spheroidal with the polar axes 21.6-34.56 mu m and the equatorial axes 23.04-33.6 mu m. The pollens are trizonocolporate. The outline is elliptic in equatorial view and triangular in polar view; amb intersemiangular. Exine sculpturing is echinate. Inter-spinal region exhibits perforate and microreticulate-perforate ornamentations. Numerical analysis revealed that dimensions of the pollen grains and surface ornamentation are the most reliable characters for delimiting the taxa within the genus.Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TUBITAK, 105T353]This work was supported by the Scientific and Technological Research Council of Turkey [grant number TUBITAK, TBAG Project No 105T353]