[Adaptation of the Seed Reproduction System to Conditions of Maritime Antarctic in Deschampsia antarctica E. Desv.].

Deschampsia antarctica E. Desv. is one of the two flowering plants that, along with Colobanthus quitensis (Kunth) Bartl., was able to settle the ice-free areas of Antarctica. In order to identify the possible adaptations of the D. antarctica reproductive system to adverse environmental conditions, comparative cytoembryological analysis of plants of this species growing on the Antarctic Peninsula with plants of the closely related species D. beringensis Hult. from the Kamchatka Peninsula was conducted. It was found that both species are characterized by sexual mode of reproduction, equal size of pollen grains (25.5 ± 2.2 and 26.2 ± 1.9 µm, respectively), same features of the embryo sac structure, and emryo- and endospermogenesis. Interspecies differences have been found in mature embryo sac size (326.8 ± 12.8 and 161.7 ± 10.4 µm), pollen sterility percentage (86.1 ± 8.9 and 35.3 ± 9.2%), and quantity of pollen in the anthers (140 ± 15.3 and 1578 ± 88.6). Possible causes and significance of these differences are discussed. No unique adaptations of seed reproduction system that are inherent exclusively to D. antarctica were found. The D. antarctica reproduction strategy is based on the combination of autogamy (and its extreme form cleistogamy) with production of excess pollen quantity for its mode of pollination.

[In planta transformation of maize through inoculation of Agrobacterium into the silks].

Integration of T-DNA into the maize genome as a result of treatment of silks with Agrobacterium cells, containing activated vir genes, was demonstrated. In planta treatment of maize (Zea mays L) was performed during flowering in field. Cell suspension of Agrobacterium tumefaiciens strain GV3101(pTd33), carrying activated vir genes, was applied onto the previously isolated silks, which were afterwards pollinated with the pollen of the same cultivar. Integration of T-DNA into maize genome was confirmed by PCR (the nptII and gus reporter genes) and hystochemical staining of the seedling tissues, obtained from the transformed seeds. Amplification of the nptII gene showed the presence of about 60.3% of PCR-positive plants out of the total number of kanamycin-resistant seedlings examined, or 6.8% of the total of number of seedlings.

[Genetic control of cytoplasmic male sterility in plants: state of the problem and current approaches]. / Geneticheskii kontrol' tsitoplazmaticheskoi myzhskoi steril'nosti rastenii: sostoianie problemy i sovremennye podkhody dlia ee issledovaniia.

The organization and functions of genetic systems controlling cytoplasmic male sterility (CMS) in plants are reviewed. Mitochondrial genes that code for specific proteins disturbing the functions of mitochondria have been found by comparisons between CMS lines and fertile F1 hybrids and between forms originating from in vitro cultures (fertile revertants, cybrids). Nuclear fertility-restorer genes abrogate expression of these mitochondrial genes at the transcriptional or posttranslational level and thereby prevent synthesis of their protein products. A high mutability of the mitochondrial genome in cells cultured in vitro results in the elimination or reorganization of CMS-associated mitochondrial genes or in new mutations causing CMS. Several biotechnological methods are considered with respect to their applicability in identifying and transferring CMS-associated genes and in constructing new CMS forms.

[Protein synthesis in maize haploids and diploids during cultivation under normal conditions and in the presence of phenol]. / Sintez bilka u haploïdiv ta dyploïdiv kukurudzy pry vyroshchuvanni ïkh za normal'nykh umov ta za prysutnosti fenolu.

14C-leucine incorporation in cytoplasmic protein was compared for three haploid forms, three derivative autodiploid lines and four hybrid forms of maize. It has been found that the precursor incorporation in the haploid forms was by 15-20% higher that in appropriate autodiploid lines. However, the level of protein synthesis wes practically the same for all investigated diploid forms. Thus, the increase of the ploidy level correlates with the decrease of the cytoplasmic protein synthesis. It was also shown that the protein content was practically equal in haploid and diploid forms. Proceeding from the authors' data one can conclude that the protein distraction may also have different intensity. The next step of the investigation was the study of the effects of the chemical factor of cytoplasmic protein synthesis in maize seedlings with different ploidy levels in vivo. It has been revealed, that the rate of 14C-leucine incorporation in the cytoplasmic proteins differ for the haploid forms which grew on the Knop media with the addition of phenol (0.05%) and without pollutant. Nevertheless, approximately equal level of 14C-leucine incorporation was observed for autodiploids. Recently it was demonstrated that the synthetic intensity of different RNA fractions is higher in the haploid maize forms than in the diploid ones and that the haploid and diploid forms of maize display the different reaction on phenol pollution. When comparing our data with the published results it is possible to conclude that the hypothesis about the low intensity of metabolism in haploid plants, existing in literature, is not true. The authors suppose that the high activity of synthesis of nuclear, transfer and ribosomal RNA and cytoplasmic proteins in the haploid plants may be connected with high mitotic activity. The authors' data are in agreement with the hypothesis that the ratio of nuclear volume and surface determines the metabolism rate.