Antarctic pearlwort ( Colobanthus quitensis ) is one of the flowering plant species considered native to maritime Antarctica. Although the species was intensively analyzed towards its morphological, anatomical and physiological adaptation to local environment, its genetic variability is still poorly studied. In the presented study, a recently developed retrotransposon−based DNA marker system (inter Primer Binding Site – iPBS) was applied to assess the genetic diversity and differentiation of C. quitensis populations from King George Island (South Shetland Islands, West Antarctic). A total of 143 scoreable bands were detected using 7 iPBS primers among 122 plant specimens representing 8 populations. 55 (38.5%) bands were found polymorphic, with an average of 14.3% polymorphic fragments per primer. Nine of all observed fragments were represented as a private bands deployed unevenly among populations. Low genetic diversity (on average H e = 0.040 and I = 0.061) and moderate population differentiation (F ST = 0.164) characterize the analyzed material. Clustering based on PCoA revealed, that the populations located on the edges of the study area diverge from the central populations. The pattern of population differentiation corresponds well with their geographic location and the characteristics of the sampling sites. Due to the character of iPBS markers, the observed genetic variability of populations may be explained by the genome rearrangements caused by mobilization of mobile genetic elements in the response to various stress factors. Additionally, this study demonstrates the usefulness of iPBS markers for genetic diversity studies in wild species.

This study investigated the details of the morphological and anatomical structure of the generative organs of the Subantarctic flowering plant, belonging to the family Caryophyllaceae - Colobanthus apetalus (Labill.) Druce. The research material was collected in hostile natural conditions in Subantarctic regions, and also was grown in the incubators and the greenhouse of the University of Warmia and Mazury in Olsztyn (Poland). C. apetalus forms tufts with soft and grassy leaves and small greenish flowers that are more obvious than in other Colobanthus species. C. apetalus forms open (chasmogamic) flowers in greenhouse cultivation. The flowers most often form five stamens with two microsporangia. Over a dozen pollen grains are formed in each microsporangium. Studies of the plant material originated from natural conditions conducted by means of a light microscope, have shown that the ovules of the analyzed representative of the genus Colobanthus are anatropous, crassinucellar, and the monosporic embryo sac develops according to the Polygonum type (the most common type in angiosperms). C. apetalus plants underwent a full development cycle in greenhouse cultivation and produced fertile, perispermic seeds. During the C. apetalus growth in conditions at increased air humidity, the vivipary was also observed.

The phytotoxic effects of fluoride and its derivatives on the seeds and seedlings of the Colobanthus apetalus and Colobanthus quitensis were studied. This is a first study to evaluate the influence of sodium fluoride (NaF) on the morphophysiological and biochemical processes on two Colobanthus species. The influence of various concentrations of NaF (9 mM, 19 mM, 29 mM) on the germination capacity and germination rate of seeds, seedlings growth and the proline content of plant tissues was analyzed under laboratory conditions (20/10°C, 12/12 h). The seeds of C. apetalus were collected from a greenhouse, whereas the seeds of C. quitensis were collected in Antarctica and in a greenhouse (Olsztyn, Poland). The tested concentrations of NaF did not suppress the germination of C. apetalus seeds, but the germination of C. quitensis seeds was inhibited. Sodium fluoride mainly inhibited root growth of C. apetalus and C. quitensis. In both analyzed species, the free proline content of seedlings increased significantly under exposure to NaF. The results of this study clearly indicate that C. apetalus and C. quitensis are highly resistant to NaF stress.