Vol 109, No 1 (2024)

The paper analyzes data on the processes occurring before and during fertilization in flowering plants. At the gametophyte stage, the gametes are formed from haploid microspores and megaspores. They are sperms, egg and central cell. The fusion of male and female gametes occurs after the pollen tube enters any synergid. One sperm fuses with the egg cell, and another from the same pollen tube joins with the central cell.

The angiosperms are likely to have four types of fertilization. These types differ in the degree of completion of syngamy. Premitotic and postmitotic types are characterized by complete syngamy, and androgamic and gynandrogamic types are inherent in incomplete syngamy. In this case, the behavior of the sperm nuclei is of great significance. They, as a rule, combine with the nuclei of female gametes (premitotic and postmitotic types), but the sperm nuclei can remain independent (gynandrogamic type) or a female nucleus is replaced by a male one (androgamic type). The premitotic type of fertilization follows the way in which the gamete protoplasts and nuclei are united before the mitosis in the zygote nucleus. As for the postmitotic type, it is carried out on a completely different basis. It is possible that in angiosperms the chromosomes of sperm and egg cell do not unite during mitosis. They further divide independently, and a diploid set of chromosomes arises in a 2-celled embryo.

Evergreen species of temperate zone acclimate to seasonal climates by reorganizations of mesophyll cell structure including chloroplast movement as a photoprotective reaction. However the exact factor inducing structural changes is still unexplored. To reveal the specific pattern of chloroplast arrangement during the annual cycle and the effect of temperature on their movement, the mesophyll cell structure in Pinus sylvestris grown out- and indoors was studied. The serial block-face scanning electron microscopy (SBF SEM) was used for the 3D imaging of mesophyll cells to show the spatial position and shape modification of chloroplasts. It has been shown that during the growing season, chloroplasts have a well-developed thylakoid system, they are located along the cell wall and occupy predominantly the part of the cell wall faced the intercellular airspace. Chloroplast movement starts in October-November, and during the winter they aggregate in the cell lobes clumping together. At that time, the thylakoid system is reorganised and consists mainly of long doubled thylakoids and small grana. The 3D reconstruction shows that the chloroplasts are irregularly oriented, swollen, and develop multiple protrusions filled by stroma that can be recognized as stromules. In indoor plants, seasonal reorganization of the mesophyll ultrastructure does not occur suggesting low temperatures but not photoperiod and light quality induce seasonal chloroplast movement in P. sylvestris mesophyll. Finally, we indicate 3D reconstruction is a powerful tool in study of low temperature-induced change of chloroplast positioning.

Magadania olaënsis (Gorovoi et N.S. Pavlova) Pimenov et Lavrova is a species of the oligotypic genus Magadania, endemic to North-Eastern Asian Russia, included in the Red Data Book of the Russian Federation. Information on its distribution in the Magadan Region, phytocenotic confinement and some features of biology is given.

The herbarium specimens of M. olaënsis are kept in 4 herbaria: MAG – 38, VLA – 8, MHA – 5, MW – 1. The type specimen (holotypus) is deposited in VLA, the paratypes are probably lost. There are 39 specimens in digital Herbaria (MAG – 38, MW – 1).

The main part of the range of M. olaënsis is located in the Magadan Region. An isolated locality on the Dzhugdzhur Ridge in the Khabarovsk Territory is also known, 730 km away from the nearest localities in the Magadan Region (Island Spafaryev). The identified area of the range of M. olaënsis in the Magadan Region is about 390 km². The largest part of the range (about 380 km²) is located on the Okhotsk–Kolyma watershed on the Ola Plateau, where the area of habitats with the highest population density (2500–3000 per km²) is about 1.5 km². Habitats on the coast of the Sea of Okhotsk take 4–5 km², and on the islands – 0.1–0.5 km². The total number of populations is approximately 4000–8500: 3500–7500 on the Okhotsk–Kolyma watershed, 600–900 on the coast, and about 50 plants on the islands.

18. olaënsis is a perennial monocarpic plant. The formation of generative shoots occurs at the age of 5–10 years. The number of generative plants in the populations is approximately the same in different years. However, there was the season when generative plants were missing in the populations on the coast. In a plant at the generative stage, in addition to the central inflorescence, 2 lateral inflorescences are usually formed (somewhat less often none or one, rarely 3–5 lateral inflorescences), but the seeds on them, even if formed, rarely reach full maturity. Real seed productivity varies significantly from year to year from 0 to 694, and averages from 146 to 326 mature seeds per plant. Seeds do not germinate at temperature +18...+22°С. The total germination percentage after two periods of stratification was 84±3.7%. Seeds of M. olaënsis are in dormancy of different depths and probably only partially germinate in the next growing season, while the rest germinate over the next few years.
19. olaënsis grows mainly in herb-shrub or shrub tundra, less often on open gravel screes at altitudes from over 700 to 1300 m a. s. l. (Okhotsk–Kolyma watershed, Zavyalov Island), or in communities with a large participation of forbs at 50–350 m a. s. l. (Atargan-Kharbiz coast, Spafaryev Island).

The main limiting factors are a strict ecological confinement of the species to basic rocks (mostly basalts), as well as exclusively seed reproduction and irregular seed renewal in different years.

Magadania olaënsis is a rare species (category 3), with III priority of conservation measures. According to the categories and criteria of the IUCN Red List the species is vulnerable (Vu). It is assigned to this category on the base of criterion B2a: a species with a limited range less than 2000 km² with a highly fragmented habitat area. Existing local protected areas in the Magadan Region do not provide protection of the species. Current data on its presence at the territory of the Dzhugdzhur Nature Reserve are contradictory and need to be clarified.

This article presents the results of the first study of the morphological and genetic diversity of 6 populations of Corydalis bracteata Pers. s. l., growing in plant communities of the Krasnoyarsk forest-steppe, Western Sayan, Kuznetsk Alatau, Altai. The morphological analysis shows the division of the populations into two groups. A large elongated tuber near basal scales, large bracts and flowers, a large height of the plants unites the from the Krasnoyarsk and Western Sayan populations with a recently described species C. talpina Stepanov. These results are also confirmed by the ISSR-PCR analysis of the genetic variability of Corydalis populations. A high subdivision coefficient (Gst = 37.58%) indicates the presence of different species in the total sample. The division into two groups is also demonstrated when clustering the genotypes using the Bayesian approach implemented in the STRUCTURE 2.3.4 software. Phylogenetic analysis based on comparison of the nucleotide polymorphism of the matK chloroplast gene sequences and the rpoB-trnC intergenic spacer also has revealed differences in three nucleotides in the plant with an additional tuber. These substitutions are absent in the sequenced plants without nodules and in sequences of other species with tufts of tubers published in GenBank. Similar results of morphological and genetic analyzes prove the differentiation of populations of yellow-flowered Corydalis in South Siberia, originally assigned to the species C. bracteata, and indicate the morphological and genetic isolation of C. talpina.

For the first time, a new invasive species Artemisia verlotiorum Lamotte has been identified in the flora of Azerbaijan (western Greater Caucasus, Lankaran Lowland, Absheron and northern Lesser Caucasus). Information is provided regarding discovered populations of the species, their number, occupied area, as well as a brief description of the phytocenoses in the places where they occur.