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Introduction. The article is devoted to the reconstruction of the events that took place in the city of Mariinsk on May 25, 1918. On this day, the Czechoslovak Corps, which was located at the railway station, rebelled. In historiography it is believed that the uprising of the Czechs and Slovaks provoked a large-scale civil war in Russia. Methods and materials. The main sources for the study were the materials of the periodical press of that time. The newspapers “Siberian Life” and “Voice of the People” published articles by correspondents who directly observed the events taking place in the city or received information from direct participants in the uprising. In addition, archival materials were used, in particular, a telegram from a member of the executive committee of the Mariinsky Soviet of Deputies, Kolesnikov. Analysis. It was established that at the end of May 1918, there were three military and political forces in the city of Mariinsk: a local Red Guard detachment; a Red Guard outsider (the so-called partisans) that arrived from the cities of Western Siberia; and a Czechoslovak Corps. During the conflict that occurred between the two Red Guard units the local Red Guards were disarmed. After that the partisans began to rob local residents and apartments of railway workers. To calm them down, the troops of the Czechoslovak Corps intervened. They quickly disarmed the partisans and took control of the city. Analysis of the telegram of Kolesnikov, a member of the executive committee of the Mariinsky Council of Deputies, showed that it is a copy of the original and contains several significant errors. In particular, the uprising of the Czechoslovak Corps took place on the evening of May 25, and not in the morning, as indicated in the telegram. The Mariinsky events became known in Moscow on the same day. The Chairman of the Supreme Military Council, L. D. Trotsky, took advantage of this to issue a brutal order for the disarmament of the Czechoslovak Corps and the physical destruction of those Czechs who would not surrender to Soviet power. Results. To some extent, the uprising of the Czechoslovak Corps was forced. It was a response to the unrest that arose in the city after the conflict between two Red Guard detachments. The central Soviet authorities in Moscow took advantage of this and ordered the actual extermination of the Czechs. This was the impetus for the emergence of large-scale military operations and Civil War in Russia. Authors' contribution. A. N. Ermolaev identified historical sources, deciphered the text of the telegram, designed the text of the article. I. Yu. Uskov participated in the deciphering of the text of the telegram and the preparation of the text of the article.

The great economic importance of sugar beet determines the ongoing biotechnological studies conducted worldwide to improve the technology of obtaining doubled haploids (DHs) using the method of unpollinated ovule culture in vitro. To improve the induction of gynogenesis, we tested the effect of thidiazuron (TDZ), temperature bud pretreatment, different concentrations of sucrose, and culturing on liquid or solid medium. Three genotypes were tested in this study. The use of TDZ at a concentration of 0.4 mg/L in solid IMB (induction medium for Beta vulgaris) induction nutrient medium with 3 g/L phytagel, 50 g/L sucrose, 200 mg/L ampicillin and cultivation at 28◦C in the dark produced up to 16.7% induced ovules. The liquid nutrient medium of the same composition induced up to 8% ovules. Increasing TDZ concentration to 0.8 mg/L resulted in reduction or total inhibition of gynogenesis, depending on the genotype. Reducing the sucrose concentration to 20 g/L or increasing it to 80 g/L was not effective. In all three genotypes, the absence of temperature pretreatment of buds (5–6 °C) showed the best results. The plant regeneration with MS nutrient medium of 20 g/L sucrose, 3 g/L phytagel, 1 mg/L 6-benzylaminopurine (BAP) and 0.1 mg/L gibberellic acid (GA3) resulted in up to seven shoots from one induced ovule in the most responsive genotype. We showed by flow cytometry, chromosome counting and chloroplast number assessment that all regenerant plants were haploid (2n = x = 9).

An important stage in doubled haploid (DH) production is to evaluate and to differentiate the ploidy level of regenerant plants at least two–three times during the technology. Therefore, rapid and reliable methods are necessary for particular species taken into the technology. In this study, Cucurbita pepo regenerants obtained through unpollinated ovule culture in vitro were evaluated including three different methods: direct chromosome counting in apical meristems, flow cytometry of the cell nucleus, and estimation of morphological parameters of the abaxial epidermis. Methods were optimized for each of three evaluations, and main criteria were determined for ploidy level differentiation. As a result, four ploidy levels, namely, 2n, 3n, 4n, and 8n, were defined among regenerant plants adapted to ex vitro conditions, while true haploids were only found among plants that remained in the in vitro culture. In total, 32.35%, 26.47%, 33.82%, 4.41%, and 2.94% of regenerant plants of courgette and patisson were diploid, triploid, tetraploid, octaploid, and aneuploid, respectively. According to results of flow cytometry of the cell nucleus, two cytotypes in diploid samples with DNA content of 2C = 1.07 ± 0.03 pg for courgette belonging to subsp. pepo and 2C = 0.95 ± 0.03 pg for patisson samples belonging to subsp. ovifera were revealed. The images of metaphase chromosomes of haploid, triploid, and tetraploid C. pepo specimens obtained using the propion–lacmoid chromosome staining method were presented for the first time. Parameters of abaxial epidermis in diploid samples of courgette and patisson grown in open-field and greenhouse conditions were described and compared. It was shown that the most robust parameter not depending on external factors was the number of chloroplasts in stomatal guard cells, which contained 9.41 to 11.31, 14.84 to 16.3, and up to 17.58 chloroplasts in diploid, triploid, and tetraploid samples, respectively. The application of several methods for estimation enables avoiding the misidentification of ploidy levels in adapted regenerant plants produced with the use of DH technology.

The centromere is a unique part of the chromosome combining a conserved function with an extreme variability in its DNA sequence. Most of our knowledge about the functional centromere organization is obtained from species with small and medium genome/chromosome sizes while the progress in plants with big genomes and large chromosomes is lagging behind. Here, we studied the genomic organization of the functional centromere in Allium fistulosum and A. cepa, both species with a large genome (13 Gb and 16 Gb/1C, 2n = 2x = 16) and large-sized chromosomes. Using low-depth DNA sequencing for these two species and previously obtained CENH3 immunoprecipitation data we identified two long (1.2 Kb) and high-copy repeats, AfCen1K and AcCen1K. FISH experiments showed that AfCen1K is located in all centromeres of A. fistulosum chromosomes while no AcCen1K FISH signals were identified on A. cepa chromosomes. Our molecular cytogenetic and bioinformatics survey demonstrated that these repeats are partially similar but differ in chromosomal location, sequence structure and genomic organization. In addition, we could conclude that the repeats are transcribed and their RNAs are not polyadenylated. We also observed that these repeats are associated with insertions of retrotransposons and plastidic DNA and the landscape of A. cepa and A. fistulosum centromeric regions possess insertions of plastidic DNA. Finally, we carried out detailed comparative satellitome analysis of A. cepa and A. fistulosum genomes and identified a new chromosome- and A. cepa-specific tandem repeat, TR2CL137, located in the centromeric region. Our results shed light on the Allium centromere organization and provide unique data for future application in Allium genome annotation.