The study contains generalized information on bioecological specifics of antarctic extremophile lime grass (Deschampsia antarctica Desv. (Poaceae)), as well as on its natural habitat and distribution factors. Peculiarities of adaptation to antarctic extreme conditions, including high heavy metal concentrations and specifics of cadmium effect on the plants’ growth, have been considered.
Specifics and conditions of D. antarctica seeds in vitro germination have been found out, and germination periodicity, as well as dependence on various factors have been researched. Common characteristics for the germination of D. antarctica from different vegetation areas have been found, such as reasonability for the use of hydrogen peroxide as a sterilizer, 98–100 % of aseptic seeds; efficacy of disturbing seeds by low temperatures (2–4ºС) and by gibberellic acid; germination under lighting. A method of producing original aseptic material for D. antarctica, specifically sterilization and germination of stratified seeds in vitro, has been developed. The method makes possible to produce morphologically normal and viable plantlets throughout the year.
Agaric nutrient medium B5, supplemented by 0.2 mg/l kinetine has been found optimal for D. antarctica microclonal reproduction. Sod fragmentation proved to be an effective way of microcloning.
Preconditions for callus formation of root and caulescent explants and lasting growth of D. antarctica tissue culture have been developed. Capacity for callus genesis depends on the mineral composition of the nutrient medium, as well as on the growth regulator concentrations’ combination, site of donor plant growth and explant type. Nutrient medium B5, supplemented by 0.9–1 mg/l 2.4-D and 0.09–0.1 mg/l BAP have been found optimal for producing callus tissue. Callus genesis activity of root explants was found to be 1.5 – 2 times as much as the one of caulescent explants. Sprouts have been produced through spontaneous indirect organogenesis. The relation between the composition of nutrient medium and callus origin on the regeneration efficiency has been established. Regenerated sprouts have been implanted and conditions for the growth of regenerant plants in vitro have been selected.
To establish the aptitude of the new methods of microclonal reproduction, a clonal breed of plants, differing in molecular-genetic markers and cytogenetic characteristics has been studied. Comparative analysis of plants at the initial stages of reproduction (passages 1–6) and under lasting cultivation in vitro (passages 24–26 and more) found no genetic differences in ISSR-markers between the clones of common origin and original genotype.
On the whole, our findings indicate that newly-developed methods can be used for the production of genetically homogenous vegetable material.
The effect of various cadmium ion concentrations on physiologic and molecular-genetic characteristics of D. antarctіca was studied with the use of genetically homogenous plants which had been grown through microclonal reproduction.
The study of the effect of various concentrations of Cd2+ (0.1–20 мМ) on in vitro cultivated D. аntarctica plants established 1 мМ as an ultimate possible concentration for the plants’ growth and development. Higher Cd2+ concentrations lead to the death of vegetation in 3 (5–20 мМ Cd2+) or 4 weeks (1.5–5 мМ Cd2+).
Inhibition of root and stem growth, decreased biomass increment, body chlorosis, rolling up, as well as slimy roots along with their blackening and fading away, formation of nontransparent liquid at the sites of plantlets bordering on the medium of high Cd ions content have been found to be the typical aftermath of Cd ions.
Effect on in vitro cultivated D. аntarctica vegetation. Cd2+ ions absorption by D. аntarctica plants from Galindez and Great Yalour islands throughout 7, 14, 21, 28 and 35 days of cultivation in vitro in the nutrient medium with different Cd2+ ions concentration has been studied. No significant difference as to cadmium accumulation by in vitro cultivated plants from these localities has been found. In either case, under effect of various cadmium ions concentrations the most of it is accumulated within first 7 days of cultivation on the metal medium.
Research of cadmium ions effect on genetic parameters of in vitro cultivated D. аntarctica plants has shown that 0.1 and 0.2 мМ concentrations would not cause changes in PCR-products’ specters. When cultivated throughout 17 days at 0.2–1 мМ CdCl2 concentration, changes in PCR-products’ specters were observed at the toxicant concentration above 0.4 мМ. Long-lasting (140–265 days) effect of cadmium ions at comparatively low concentrations (0.1 мМ and 0.4 мМ) would not cause appreciable genome changes.
Our findings are indicative of D. antarctica resistance to cadmium ions as compared to the other vascular plants, cited in scientific sources.
Thus, on the basis of our research we have developed efficient techniques of D. antarсtica
