scholarly journals Development of the pollen in the antarctic flowering plant Colobanthus quitensis (Kunth) Bartl.

2012 ◽  
Vol 60 (2) ◽  
pp. 3-8 ◽  
Author(s):  
Irena Giełwanowska ◽  
Anna Bochenek ◽  
Ewa Szczuka
Keyword(s):  
Osmotic Stress ◽  
Flowering Plant ◽  
Natural Conditions ◽  
Callose Wall ◽  
Colobanthus Quitensis ◽  
Mother Cells ◽  
The Antarctic

<i>Colobanthus quitensis</i> (Kunth) Bartl. produced two types very small bisexual fl owers. In the Antarctic natural conditions chasmogamic and cleistogamic fl owers most often form fi ve stamina with short fi laments. 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 <i>Colobanthus quitensis</i> 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.

scholarly journals Biology of generative reproduction of Colobanthus quitensis (Kunth) Bartl. from King George Island, South Shetland Islands

2011 ◽  
Vol 32 (2) ◽  
pp. 139-155 ◽  
Author(s):  
Irena Giełwanowska ◽  
Anna Bochenek ◽  
Ewa Gojło ◽  
Ryszard Görecki ◽  
Wioleta Kellmann ◽  
...  
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
South Shetland Islands ◽  
Egg Cell ◽  
Strong Wind ◽  
King George Island ◽  
Natural Conditions ◽  
Shetland Islands ◽  
Colobanthus Quitensis ◽  
The Antarctic

Biology of generative reproduction of Colobanthus quitensis (Kunth) Bartl. from King George Island, South Shetland Islands Our macroscopic observations and microscopic studies conducted by means of a light microscope (LM) and transmission electron microscope (TEM) concerning the re-production biology of Colobanthus quitensis (Caryophyllaceae) growing in natural conditions in the Antarctic and in a greenhouse in Olsztyn (northern Poland) showed that this plant develops two types of bisexual flowers: opening, chasmogamous flowers and closed, cleistogamous ones. Cleistogamy was caused by a low temperature, high air humidity and strong wind. A small number of microspores differentiated in the microsporangia of C. quitensis, which is typical of cleistogamous species. Microsporocytes, and later microspores, formed very thick callose walls. More than twenty spheroidal, polypantoporate pollen grains differentiated in the microsporangium. They germinated on the surface of receptive cells on the dry stigma of the gynoecium or inside the microsporangium. A monosporic embryo sac of the Polygonum type differentiated in the crassinucellar ovule. During this differentiation the nucellus tissue formed and stored reserve materials. In the development of generative cells, a male germ unit (MGU) with differentiated sperm cells was observed. The smaller cell contained mainly mitochondria, and the bigger one plastids. In the process of fertilization in C. quitensis only one nucleus of the sperm cell, without cytoplasm fragments, entered the egg cell, and the proembryo developed according to the Caryophyllad type. Almost all C. quitensis ovules developed and formed perispermic seeds with a completely differentiated embryo both under natural conditions in the Antarctic and in a green-house in Olsztyn.

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

2012 ◽  
Vol 59 (1) ◽  
pp. 123-131
Author(s):  
Irena Giełwanowska ◽  
Ewa Szczuka ◽  
Anna Bochenek
Keyword(s):  
Abiotic Factors ◽  
Pollen Grains ◽  
Flowering Plant ◽  
Strong Wind ◽  
Air Humidity ◽  
Colobanthus Quitensis ◽  
Cross Pollination ◽  
Stigma Surface ◽  
Favorable Conditions ◽  
The Antarctic

<i>Colobanthus quitensis</i> 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.

scholarly journals Asymmetric responses to simulated global warming by populations of Colobanthus quitensis along a latitudinal gradient

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3718 ◽  
Author(s):  
Ian S. Acuña-Rodríguez ◽  
Cristian Torres-Díaz ◽  
Rasme Hereme ◽  
Marco A. Molina-Montenegro
Keyword(s):  
Global Warming ◽  
Latitudinal Gradient ◽  
Biomass Accumulation ◽  
South Shetland Islands ◽  
Plant Populations ◽  
Colobanthus Quitensis ◽  
Growing Seasons ◽  
Long Term Experiment ◽  
Foliar Traits ◽  
The Antarctic

The increase in temperature as consequence of the recent global warming has been reported to generate new ice-free areas in the Antarctic continent, facilitating the colonization and spread of plant populations. Consequently, Antarctic vascular plants have been observed extending their southern distribution. But as the environmental conditions toward southern localities become progressively more departed from the species’ physiological optimum, the ecophysiological responses and survival to the expected global warming could be reduced. However, if processes of local adaptation are the main cause of the observed southern expansion, those populations could appear constrained to respond positively to the expected global warming. Using individuals from the southern tip of South America, the South Shetland Islands and the Antarctic Peninsula, we assess with a long term experiment (three years) under controlled conditions if the responsiveness of Colobanthus quitensis populations to the expected global warming, is related with their different foliar traits and photoprotective mechanisms along the latitudinal gradient. In addition, we tested if the release of the stress condition by the global warming in these cold environments increases the ecophysiological performance. For this, we describe the latitudinal pattern of net photosynthetic capacity, biomass accumulation, and number of flowers under current and future temperatures respective to each site of origin after three growing seasons. Overall, was found a clinal trend was found in the foliar traits and photoprotective mechanisms in the evaluated C. quitensis populations. On the other hand, an asymmetric response to warming was observed for southern populations in all ecophysiological traits evaluated, suggesting that low temperature is limiting the performance of C. quitensis populations. Our results suggest that under a global warming scenario, plant populations that inhabiting cold zones at high latitudes could increase in their ecophysiological performance, enhancing the size of populations or their spread.

Autoradiography of Soluble [2-14C]Thymidine Derivatives During Meiosis And Microsporogenesis in Lilium Anthers

1967 ◽  
Vol 2 (3) ◽  
pp. 387-400 ◽  
Author(s):  
J. HESLOP-HARRISON ◽  
A. MACKENZIE
Keyword(s):  
Meiotic Prophase ◽  
Trichloroacetic Acid ◽  
Thymidine Incorporation ◽  
Callose Wall ◽  
Autoradiographic Method ◽  
Tapetal Cells ◽  
Mother Cells

A dry autoradiographic method suitable for locating soluble tracers has been used to follow the fate of [2-14C]thymidine supplied to detached buds and inflorescences of Lilium henryi and a related cultivar. During the interval from the archesporial phase until pachytene, the derivative (or derivatives) reaching the anther loculi moved freely into the meiocytes. Subsequently, the tracer was excluded from the mother cells until the dissolution of the tetrads. The young spores readily took up tracer in the thecal fluid upon their release, and yielded strongly localized autoradiographs. These observations are interpreted as indicating that access of materials to the meiocytes is related to the formation of cytoplasmic links between mother cells in the early meiotic prophase, and the later severance of these links through the growth of the isolating callose wall which comes to invest the tetrads. Judged from the tracer retained in preparations extracted with trichloroacetic acid, thymidine incorporation occurs mostly in the premeiotic and early leptotene period, although there is some slight evidence of incorporation later in prophase. In the tapetal cells, incorporation occurred in most of the stages tested, but there was no indication of a transfer of labelled materials from tapetum to spores in the post-meiotic period.

scholarly journals Decomposition of Calcium Oxalate Crystals in Colobanthus quitensis under CO2 Limiting Conditions

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1307
Author(s):  
Olman Gómez-Espinoza ◽  
Daniel González-Ramírez ◽  
Panagiota Bresta ◽  
George Karabourniotis ◽  
León A. Bravo
Keyword(s):  
Calcium Oxalate ◽  
Electron Transport Rate ◽  
Relative Size ◽  
Oxalate Oxidase ◽  
Stress Factors ◽  
Calcium Oxalate Crystals ◽  
Colobanthus Quitensis ◽  
Diffusion Limitations ◽  
Co2 Diffusion ◽  
The Antarctic

Calcium oxalate (CaOx) crystals are widespread among plant species. Their functions are not yet completely understood; however, they can provide tolerance against multiple environmental stress factors. Recent evidence suggested that CaOx crystals function as carbon reservoirs since its decomposition provides CO2 that may be used as carbon source for photosynthesis. This might be advantageous in plants with reduced mesophyll conductance, such as the Antarctic plant Colobanthus quitensis, which have shown CO2 diffusion limitations. In this study, we evaluate the effect of two CO2 concentrations in the CaOx crystals decomposition and chlorophyll fluorescence of C. quitensis. Plants were exposed to airflows with 400 ppm and 11.5 ppm CO2 and the number and relative size of crystals, electron transport rate (ETR), and oxalate oxidase (OxO) activity were monitored along time (10 h). Here we showed that leaf crystal area decreases over time in plants with 11.5 ppm CO2, which was accompanied by increased OxO activity and only a slight decrease in the ETR. These results suggested a relation between CO2 limiting conditions and the CaOx crystals decomposition in C. quitensis. Hence, crystal decomposition could be a complementary endogenous mechanism for CO2 supply in plants facing the Antarctic stressful habitat.

Leishmanicidal and antitumoral activities of endophytic fungi associated with the Antarctic angiosperms Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl.

Extremophiles ◽  
2011 ◽  
Vol 16 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Iara F. Santiago ◽  
Tânia M. A. Alves ◽  
Ana Rabello ◽  
Policarpo A. Sales Junior ◽  
Alvaro J. Romanha ◽  
...  
Keyword(s):  
Endophytic Fungi ◽  
Deschampsia Antarctica ◽  
Colobanthus Quitensis ◽  
The Antarctic
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