Rozwoj pylku u antarktycznej rosliny naczyniowej Colobanthus quitensis [Kurth] Bartl.

Colobanthus quitensis (Kunth) Bartl, produced two types very small bisexual flowers. In the Antarctic natural conditions chasmogamic and cleistogamic flowers most often form five stamina with short filaments. Two microsporangia with a three-layer wall form in the anther. Microspore mother cells, which develop into microspores after meiosis, form inside the microsporangium. Microsporocytes of Colobanthus quitensis are surrounded with a thick callose layer, the special wall. After meiosis, the callose wall is dissolved and microspores are released from the tetrad. The production of proorbicules, orbicules and peritapetal membrane, and the construction of a complex sporoderm with numerous apertural sites were observed. When microspore and pollen protoplasts underwent necrosis, probably as a result of temperature and osmotic stress, sporoderm layers formed around microspores, and the cell tapetum did not disintegrate. However, woody wall layers did not accumulate in endothecium cells.Colobanthus quitensis, jedyna dwuliścienna roślina kwiatowa rosnąca w ekstremalnie niesprzyjających warunkach antarktycznej strefy geobotanicznej, wykształca zróżnicowane, obupłciowe kwiaty; chasmogamiczne i kleistogamiczne. Kleistogamia jest tu indukowana niską temperaturą dużą wilgotnością powietrza i silnym wiatrem. W mikrosporangiach Colobanthus quitensis różnicowała się mała liczba mikrospor, co jest cechą typową dla gatunków z kleistogamią. Mikrosporocyty tworzyły bardzo grube kalozowe ściany specjalne. Nie było jednak kalozy w ścianie oddzielającej komórkę generatywną od wegetatywnej. W rozwoju pyłku Colobanthus quitensis zaobserwowano męską jednostkę rozrodczą ze zróżnicowanymi komórkami plemnikowymi. Mniejsza komórka zawierała przede wszystkim mitochondria, a większa głównie piastydy. Dojrzały pyłek wysypywał się z mikrosporangium lub kiełkował na miejscu. Obserwowano trójkomórkowe ziarna pyłku z łagiewkami wewnątrz otwartych pylników

Pollination in the Antarctic flowering plant Colobanthus quitensis (Kunth) Bartl.

Colobanthus quitensis forms chasmogamic and cleistogamic flowers. Their structure signals the possibility of both cross-pollination and self-pollination. In favorable conditions (natural or laboratory), flowers open creating a possibility for cross-pollination. The occurrence of cleistogamy in the investigated species may be conditioned by abiotic factors: low temperature, high air humidity, and strong wind. In closed flowers, a part of pollen grains reaches the stigma surface, and the rest remains inside the microsporangium. Pollen grains germinate on the stigma surface or inside the microsporangium. Often, two or more pollen tubes grow from a single pollen grain. Closed flowers and the direct contact between the style stigma and anther prove the preference for autogamy. Autogamy ensures the reproductive success of the investigated plant in the exceptionally harsh Antarctic environment.Colobanthus quitensis wytwarza kwiaty chasmogamiczne i kleistogamicz- ne. Ich budowa wskazuje na możliwość zarówno obcopylności, jak i samopylności. W sprzyjających warunkach (naturalnych lub laboratoryjnych) kwiaty otwierają się i wtedy istnieje możliwość krzyżowego zapylenia. Występowanie kleistogamii u ba- danego gatunku może być uwarunkowane czynnikami abiotycznymi: niską tempe- raturą, wysoką wilgotnoścą powietrza oraz silnym wiatrem. W zamkniętych kwia- tach część pyłku dostaje się na powierzchnię znamienia a część pozostaje wewnątrz mikrosporangium. Ziarna pyłku kiełkują na powierzchni znamienia lub wewnątrz mikrosporangium. Z pojedynczego ziarna pyłku wyrasta często dwie albo więcej ła- giewek. Zamknięte kwiaty i bezpośredni kontakt znamion słupków z pylnikami prę- cików dowodzą preferencji autogamii. Autogamia zapewnia sukces reprodukcyjny badanej rośliny w wyjątkowo surowym środowisku Antarktyki

Influence of environmental factors on reproduction of polar vascular plants

In the last few decades, changes of reproductive pattern of polar vascular plants have been observed, for the benefit of generative propagation. The reasons for this phenomenon are attributed to intensively following climate change, whose effects may be various. Warming causes the production of the greater number of generative structures, with higher quality. Our macroscopic observations conducted on specimens of polar vascular plants, cultivated in University of Warmia and Mazury greenhouse, indicate that the effect of temperature increase on flower development and seed formation is inconsistent. On the other hand enhanced levels of UV-B radiation can negatively affect seedlings. The complexity of the climate change causes tremendous difficulties in defining a clear and unquestioned way of modifications during the reproductive phase of the described plants

Influence of environmental changes on physiology and development of polar vascular plant

Polar vascular plants native to the Arctic and the Antarctic geobotanical zone have been growing and reproducing effectively under difficult environmental conditions, colonizing frozen ground areas formerly covered by ice. Our macroscopic observations and microscopic studies conducted by means of a light microscope (LM) and transmission electron microscope (TEM) concerning the anatomical and ultrastructural observations of vegetative and generative tissue in Cerastium arcticum, Colobanthus quitensis, Silene involucrata, plants from Caryophyllaceae and Deschampsia antarctica, Poa annua and Poa arctica, from Poaceae family. In the studies, special attention was paid to plants coming from diversity habitats where stress factors operated with clearly different intensity. In all examinations plants, differences in anatomy were considerable. In Deschampsia antarctica the adaxial epidermis of hairgrass leaves from a humid microhabitat, bulliform cells differentiated. Mesophyll was composed of cells of irregular shapes and resembled aerenchyma. The ultrastructural observations of mesophyll in all plants showed tight adherence of chloroplasts, mitochondria and peroxisomes, surface deformations of these organelles and formation of characteristic outgrowths and pocket concavities filled with cytoplasm with vesicles and organelles by chloroplasts. In reproduction biology of examined Caryophyllaceae and Poaceae plants growing in natural conditions, in the Arctic and in the Antarctic, and in a greenhouse in Olsztyn showed that this plant develops two types of bisexual flowers. Almost all ovules developed and formed seeds with a completely differentiated embryo both under natural conditions in the Arctic and the Antarctic and in a greenhouse in Olsztyn

Carbohydrates in Colobanthus quitensis and Deschampsia antarctica

Eight to nineteen ethanol-soluble carbohydrate components were identified in vegetative tissues of Colobanthus quitensis and Deschampsia antarctica. The analysed carbohydrates included: monosaccharides, cyclitols, galactosyl cyclitols, raffinose family oligosaccharides, lichnose family oligosaccharides, kestose family oligosaccharides. The analysed vegetative tissues accumulated from 447 to 139 mg/g d.m. soluble carbohydrates in Colobanthus quitensis, Deschampsia antarctica respectively. The raffinose family oligosaccharides constituted 53.3% in Colobanthus quitensis of the identified soluble carbohydrate component pool. Vegetative tissues accumulated starch in Colobanthus quitensis 20.6 mg/g d.m. and 261.6 mg/g d.m. in Deschampsia antarctica. Anatomical and ultrastructural observations of vegetative part of Colobanthus quitensis and Deschmpsia antarctica revealed the presence of various ergastic materials in intercellular spaces, cell walls and protoplasts. Various parts of these plants contain insoluble, PAS positive polysaccharides in intercellular spaces and in cell walls. Chloroplasts of analysed tissues contained starch. Less starch was visible in young, growing parts of shoots of Colobanthus quitensis and Deschmpsia antarctica, more starch appears in mature, differentiated parts