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The embryology of three polar flowering plants of the family Caryophyllaceae was studied using the methods and techniques of the light, normal and fluorescence microscopes, and the electron microscopes, scanning and transmission. The analyzed species were Colobanthus quitensis of West Antarctic (King George Island, South Shetlands Islands) as well as Cerastium alpinum and Silene involucrata of the Arctic (Spitsbergen, Svalbard). In all evaluated species, flowering responses were adapted to the short Arctic and Australian summer, and adaptations to autogamy and anemogamy were also observed. The microsporangia of the analyzed plants produced small numbers of microspore mother cells that were differentiated into a dozen or dozens of trinucleate pollen grains. The majority of mature pollen grains remained inside microsporangia and germinated in the thecae. The monosporous Polygonum type (the most common type in angiosperms) of embryo sac development was observed in the studied species. The egg apparatus had an egg cell and two synergids with typical polarization. A well-developed filiform apparatus was differentiated in the micropylar end of the synergids. In mature diaspores of the analyzed plants of the family Caryophyllaceae, a large and peripherally located embryo was, in most part, adjacent to perisperm cells filled with reserve substances, whereas the radicle was surrounded by micropylar endosperm composed of a single layer of cells with thick, intensely stained cytoplasm, organelles and reserve substances. The testae of the analyzed plants were characterized by species-specific primary and secondary sculpture, and they contained large amounts of osmophilic material with varied density. Seeds of C. quitensis, C. alpinum and S. involucrata are very small, light and compact shaped.

Common buckwheat (Fagopyrum esculentum Moench) is the only crop that contains D-chiro-inositol (DCI) in significant contents in vegetative tissues and its a-D-galactosyl derivatives in seeds. Besides DCI, buckwheat tissues contain small contents of D-pinitol (PIN) and myo-inositol (MIN) and their a-D-galactosyl derivatives. D-chiro-inositol is a health-promoting cyclitol of increasing importance in the treatment of some human diseases. However, changes in DCI content in stems, leaves and maturing buckwheat seeds during plant vegetation and under desiccation were not known. The present study analyzed the concentration of cyclitols and their galactosides in the stems, leaves and seeds of plants harvested on 79th, 94th and 123th days after sowing (DAS) and after desiccation at ambient temperature (23° ±2°C). D-chiro-inositol content in stems and leaves increased with vegetation, while the opposite trend was found in developing and maturing seeds. In the seeds, the accumulation of mono-galactosyl DCI derivatives increased, but at the same time, the content of mono-galactosyl PIN and MIN derivatives decreased. The desiccation process drastically increased the content of di-galactosyl derivatives of DCI and MIN in the seeds. The obtained results suggest a protective role of DCI and MIN di-galactosides against desiccation stress in buckwheat tissues. [ABSTRACT FROM AUTHOR]