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Abstract

The development of megasporocytes and the functional megaspore formation in Deschampsia antarctica were analyzed with the use of microscopic methods. A single archesporial cell was formed directly under the epidermis in the micropylar region of the ovule without producing a parietal cell. In successive stages of development, the meiocyte was transformed into a megaspore tetrad after meiosis. Most megaspores were arranged in a linear fashion, but some tetrads were T-shaped. Only one of the 60 analyzed ovules contained a cell in the direct proximity of the megasporocyte, which could be an aposporous initial. Most of the evaluated D. antarctica ovules featured monosporic embryo sacs of the Polygonum type. Approximately 30% of ovules contained numerous megaspores that were enlarged. The megaspores were located at chalazal and micropylar poles, and some ovules featured two megaspores - terminal and medial - in the chalazal region, or even three megaspores at the chalazal pole. In those cases, the micropylar megaspore was significantly smaller than the remaining megaspores, and it did not have the characteristic features of functional megaspores. Meiocytes and megaspores of D. antarctica contained polysaccharides that were detectable by PAS-reaction and aniline blue staining. Starch granules and cell walls of megasporocytes, megaspores and nucellar cells were PAS-positive. Fluorescent callose deposits were identified in the micropylar end of the megasporocytes. During meiosis and after its completion, thick callose deposits were also visible in the periclinal walls and in a small amount in the anticlinal walls of megaspores forming linear and T-shaped tetrads. Callose deposits fluorescence was not observed in the walls of the nucellar cells.
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Authors and Affiliations

Marcin Domaciuk
Irena Giełwanowska
Agata Leszczuk
Ewa Szczuka
Wioleta Kellmann-Sopyła
Justyna Koc
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Abstract

Populations of Antarctic hairgrass Deschampsia antarctica Desv. from King George Island exhibit variation in many traits. The reason for that is not evident and could be addressed to variable environmental conditions. Obviously, phenotypic variation could be due to stable or temporal changes in expression pattern as the result of adaptation. Stable changes could be due to mutations or site DNA methylation variation that modified expression pattern. Recently, metAFLP approach was proposed to study such effects. A variant of methylation sensitive AFLP (Amplified Fragment Length Polymorphism), based on the isoschizomeric combinations Acc65 I/ Mse I and Kpn I/ Mse I was applied to analyze the sequence and site DNA methylation differences between two D. antarctica populations exhibiting morphological dissimilarities. Both DNA sequence mutations and site methylation pattern alternations were detected among and within analyzed populations. It is assumed that such changes might have originated as the response to environmental conditions that induced site methylation alternations leading to phenotypic variation of D. antarctica populations from South Shetland Islands.
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Authors and Affiliations

Katarzyna J. Chwedorzewska
Piotr B. Bednarek
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Abstract

Different chromosomal forms of Deschampsia antarctica Desv. (Poaceae), including diploids (2n=26), hypotriploid (2n=36–38) and a genotype with an occasional occurrence of B chromosome (2n=26+0-1B) that originated from southern marginal populations (Argentine Islands region, maritime Antarctic) were studied using molecular cytogenetic, morphometric and biochemical methods. FISH analysis revealed variations in the number of rDNA sites between the diploid and hypotriploid plants. The genome size varied among plants with a different chromosome number and was on average 10.88 pg/2C for diploids and 16.46 pg/2C for hypotriploid. The mean values of leaf length of plants grown in vitro varied within a range of 5.23–9.56 cm. The total phenolic content ranged from 51.10 to 105.40 mg/g, and the total flavonoid content ranged from 1.22 to 4.67 mg/g. The amount of phenolic compounds did not differ significantly between the genotypes, while a variation in the flavonoid content was observed for L59 and DAR12. The diploids did not differ significantly among each other in terms of the number of rDNA loci, but differed slightly in their genome size. The individuals of DAR12 carrying B chromosome were similar to other diploids in terms of their genome size, but statistically differed in leaf length. The hypotriploid had both a greater number of rDNA sites and a larger genome size. No statistical correlations were observed between the genome size and leaf length or genome size and accumulation of phenolic and flavonoid compounds. The results of this study suggest that D. antarctica plants from the southern edge of the range are characterised by the heterogeneity of the studied parameters.

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Authors and Affiliations

Daria Navrotska
Igor Andreev
Alexander Betekhtin
Magdalena Rojek
Ivan Parnikoza
Ganna Myryuta
Oksana Poronnik
Natalia Miryuta
Joanna Szymanowska-Pułka
Volodymyr Grakhov
Roman Ivannikov
Robert Hasterok
Viktor Kunakh
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Abstract

This paper presents a comparative study on the anatomy of the Antarctic hairgrass (Deschampsia antarctica É. Desv.) from natural populations of two distant maritime Antarctic regions: the Argentine Islands (Antarctic Peninsula region) and the Point Thomas oasis (King George Island, South Shetland Islands). Comparison of D. antarctica plants from natural populations of Argentine Islands region and plants originated from seeds of these populations cultivated in vitro also was made. Additionally anatomical features of Deschampsia antarctica were compared with ones for D. caespitosa. The results of our study do not provide enough evidence to assert more pronounced xerophytic anatomical features in D. antarctica plants from more harsh conditions of Argentine Islands region. Such features (both qualitative and quantitative) of D. antarctica mainly depend on local conditions, and not on the latitudinal or climatic gradient. In both regions it is possible to find individuals that represent different ecotypes which are adopted to open arid or more humid habitats. It has been shown that Antarctic hairgrass plants germinated from seeds and cultivated in vitro retain the qualitative anatomy features that are typical to plants from the initial natural populations. This is especially noticeable in the case of plants from Berthelot Island (BE1 study plots), which might indicate a genetic fixation and a manifested differentiation similar to DNA haplotypes or chromosomal forms. However, quantitative characteristics, in particular the epidermis parameters, are subject to changes due to the transfer to more favourable conditions. Also qualitative and quantitative difference of D. antarctica in contrast with D. caespitosa have been described. These differences could be useful for identifying these two species. Additionally the quantitative differences (such as the area of the epidermal cells and the number and size of stomata on the adaxial surface) of Alaskan D. caespitosa grown from seeds were detected in contrast to the naturally grown plants of the same species from Ushuaia.

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Authors and Affiliations

Nataliia Nuzhyna
ORCID: ORCID
Ivan Parnikoza
ORCID: ORCID
Oksana Poronnik
ORCID: ORCID
Iryna Kozeretska
Viktor Kunakh
ORCID: ORCID
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Abstract

The paper presents data on the total phenolic and flavonoid content in Deschampsia antarctica È. Desv. plants collected from natural habitats, plants cultured in vitro, regenerated plants, and plants cultivated in a growth chamber. It was found that the shoots (aerial parts) had higher phenolic and flavonoid contents compared to the roots. The largest amount of these substances was found in wild plants from Great Yalour Island. The content of phenolics and flavonoids in plants cultured in vitro was generally comparable to that in plants collected from natural habitats except for some clones. HPLC analysis revealed five main metabolites present in similar ratios in the studied samples of wild and in vitro plants. Minor substances varied slightly in different extracts, however their presence did not depend on plant growth conditions. No significant qualitative differences in HPLC profiles were found between the wild and in vitro plants. The studied samples did not contain quercetin, kaempferol and luteolin, whereas orientin was found in all studied samples of D. antarctica.
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Authors and Affiliations

Maryana Twardovska
1
ORCID: ORCID
Iryna Konvalyuk
1
ORCID: ORCID
Kateryna Lystvan
2
Igor Andreev
1
ORCID: ORCID
Ivan Parnikoza
1 3
ORCID: ORCID
Viktor Kunakh
1
ORCID: ORCID

  1. Department of Cell Population Genetics, Institute of Molecular Biology and Genetics of the National Academy of Sciences of Ukraine,150 Acad. Zabolotnogo Str., 03143, Kyiv, Ukraine
  2. Department of Genetic Engineering, Institute of Cell Biology and Genetic, Engineering of the National Academy of Sciences of Ukraine, 148 Acad. Zabolotnogo Str., 03143, Kyiv, Ukraine
  3. State Institution National Antarctic Scientific Center, Ministry of Education and Science of Ukraine, 16 Shevchenko Ave., 01601, Kyiv, Ukraine

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