Procedures for the direct regeneration of entire plants from a shoot and root protoplasts of Arabidopsis thaliana have been optimized. The culture media for protoplast donor-plant cultivation and protoplast culture have been adjusted for optimal plant growth, plating efficiency, and promotion of shoot regeneration. Protocols have been established for the detection of all three steps in plant regeneration: (i) chromatin relaxation and activation of auxin biosynthesis, (ii) cell cycle progression, and (iii) conversion of cell-cycle active cells to totipotent ones. The competence for cell division was detected by DNA replication events and required high cell density and high concentrations of the auxinic compound 2,4-D. Cell cycle activity and globular structure formation, with subsequent shoot induction, were detected microscopically and by labeling with fluorescent dye Rhodamine123. The qPCR results demonstrated significantly upregulated expression of the genes responsible for nuclear reorganization, auxin responses, and auxin biosynthesis during the early stage of cell reprogramming. We further optimized cell reprogramming with this protocol by applying glutathione (GSH), which increases the sensitivity of isolated mesophyll protoplasts to cell cycle activation by auxin. The developed protocol allows us to investigate the molecular mechanism of the de-differentiation of somatic plant cells.

The work is aimed at the selection of linear samples of zucchini (Cucurbita pepo L. var. Giromontia Duch.) with increased complex resistance to abiotic factors of cultivation – zucchini yellow mosaic virus (ZYMV), powdery mildew, bacteriosis and other viral pathogens. Selection studies on choosing virus-resistant zucchini lines from the United Kingdom, Italy, the United States and Spain have identified a number of important correlations levels of resistance to ZYMV and to harmful microorganisms and viruses, belonging to other genera. The assessment of the resistance of the selected zucchini lines to the complex of studied diseases was performed on a 9-point scale of the classifier of the Council for Mutual Economic Assistance (CMEA). In total, during 2017–2019, 20 lines of zucchini were studied in the field. According to the complex resistance to all pathogens (zucchini yellow mosaic virus, green speckled mosaic, white mosaic and cucumber mosaic, bacteriosis and fusarium wilt), four lines have been identified – LZ 17-11, RVL-19, LZ 17-45 and LZ 17-49, which were resistant at the level of points 7 and 9 on the scale of CMEA. The possibility of selecting potentially resistant linear zucchini genotypes for ZYMV based on correlations with the manifestation of other diseases that occurred in the field has been confirmed. The highest level of correlation 0.59<rp<1.0) is observed when comparing the degree of powdery mildew development and symptoms of ZYMV (17 statistically confirmed values of the pairwise correlation coefficient or 80.95 %). A similar indicator for the pair “bacteriosis/ZYMV” is 14 statistically confirmed values of the pairwise correlation coefficient or 66.67 % (–1.0<rp<0.99), and for the pair “field viruses of other origin/ZYMV” – 11 values, which is 52.38 % (–1.0<rp<0.93). Zucchini samples were identified, in which statistically significant correlations were observed for all pairs of comparative traits. Among them, the variety-standard Chaklun and 4 more lines – LZ 17-1, LZ 17-8, LZ 17-50 and LZ 17-44 (–1.0<rp<0.92). The analysis of correlations shows a complex genetic organization of signs of resistance in zucchini lines to the studied pathogens and a high dependence of the manifestation of these signs on the response of the genotype of the line. One of the proofs of this experimental fact is that in all comparative pairs of indicators of the degree of development of certain diseases there are linear genotypes with both positive and negative values of Pearson correlation coefficients (rp). The high level of statistically significant correlations revealed gives grounds for wide use of correlation analysis in selection work for choosing lines potentially resistant to the complex of the most common diseases in vegetable agrocenoses

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Мета. Оцінити адаптивний потенціал гібридів F1 кабачка зарубіжної селекції за комплексом кількісних цінних ознак. Методи. Об’єкт досліджень – 19 гібридів F1 походженням з США, Великобританії, Іспанії і Італії. Стандарт – вітчизняний гібрид Атілла F1. Для оцінки параметрів адаптивної здатності і екологічної пластичності гібридів F1 використовували наступні показники: загальна і специфічна адаптивна здатність генотипу (ЗАЗi і САЗi); відносна стабільність (Sgi); коефіцієнт екологічної пластичності (bi); селекційна цінність генотипу (СЦГi). Результати. За результатами досліджень 2017–2019 років для агрокліматичної зони Лівобережного Лісостепу України виділено перспективні гібриди F1 як цінні генетичні джерела для адаптивної селекції кабачка. Серед проаналізованих гібридів F1 виділилося два зразки Alexander F1 (К-2128) і Mikinos F1 (К-2129), які мали, у порівнянні зі стандартом, кращі показники адаптивного потенціалу та вищі показники загальної урожайності (Xmed = 72,28…79,05 т/га, СЦГ і = 39,60…68,12) та вмісту вітаміну С у плодах (Xmed = 11,92…12,01 мг/100 г, СЦГi = 4,82…10,55). Ще один гібрид, Paychek F1 (К-2132), мав високий адаптивний потенціал та рівень прояву за трьома кількісними ознаками – загальною урожайністю (Xmed = 78,16 т/га, СЦГi = 53,87), вмістом загального цукру (Xmed = 2,81 %; СЦГi = 1,54) та вітаміну С у плодах (Xmed = 19,64 мг/100 г, СЦГi = 8,15). Висновки. Виділено три перспективних, високоврожайних гібридів F1 кабачка (Mikinos F1 (К-2129), Paychek F1 (К-2132) Alexander F1 (К-2128)), які за рівнем прояву ознаки “Загальна урожайність” належать до інтенсивного типу вирощування (bi > 1). Виділено чотири гібриди F1 (Gold Rush F1 (К-2125), Afrodite F1 (К-2126), Celeste F1 (К-2127) та Cronos F1 (К-2131)), які за проявом ознаки “Вміст загального цукру у плодах” та чотири гібридні зразки (Best of British F1 (К-2116), Defender F1 (К-2117), Eight Ball F1, Cronos F1 (К-2131)), які за проявом ознаки “Вміст вітаміну С у плодах” продемонстрували низьку залежність від умов вирощування (bi < 1) і є цінними генетичними джерелами для адаптивної селекції. Виділено 2 гібриди F1 (Mikinos F1 (К-2129), Paychek F1 (К-2132)), у яких був більш подовжений період плодоношення майже на 7–12 діб у порівнянні з стандартом. За період 2017–2019 рр. до комплексу основних збудників хвороб (вірусів, бактеріозу і фузаріозу) та шкідника попелиці виділено один гібридний зразок – Celeste F1 (К-2127), у якого спостерігався рівень стійкості на рівні 7 і 9 балів за шкалою РЕВ.

The Major Histocompatability Complex (MHC) determines the immune response to pathogens, and its genes are promising candidates for the search of associations with diseases. A special role is played by BoLA-DRB3 gene, the product of which directly participates in the binding of alien antigens and conditions the specificity of the immune response. The second exon of this gene codes β1-domain of class II antigens, which is necessary for binding a broad spectrum of alien antigens. Exon 2 of BoLA-DRB3 gene is extremely polymorphic, giving the possibility to search the associations of its alleles with various diseases. The article provides the results of the study on polymorphism of alleles of BoLA-DRB3.2 gene for detection of its associations with sensitivity to fusobacteriosis (necrobacteriosis) of cows. The survey was performed using PCR-RFLP method with DNA of blood from 176 cows of two herds of Ukrainian black-and-white dairy breed. As a result of the studies, in the first herd, 25 BoLA-DRB3.2 alleles were found. In the selections of nectobacteriosis susceptible and resistant cows, we found 22 and 21 variants respectively. In the second herd, in the general selection and group of healthy animals, 27 alleles were typed, and 22 in the group of susceptible cows. BoLA-DRB3.2*22 allele was the commonest in both herds in both general selections and groups of nectobacteriosis-resistant cows. In the selection of susceptible animals, the commonest was the variant BoLA-DRB3.2*16. We determined statistically significant associations of BoLA-DRB3.2 alleles with sensitivity to nectobacteriosis of cattle. BoLA-DRB3.2*03 and *22 alleles associate with nectobacteriosis-resistant, while *16 and *23 – with nectobacteriosis-susceptible cows of the both studied groups. Also, in the first herd, another allele was found – *24, indicating close relationship with the disease. The studies of polymorphism of BoLA-DRB3 gene expand the knowledge about genetic peculiarities of the Ukrainian black-and-white dairy breed. The identified molecular-genetic markers could be useful for breeders whose work is oriented towards the formation of herds which are resistant to diseases of the limbs in cattle.