The article contains the data on creating and maintaining the collections in vitro of some ornamental plants – lilac, roses, tree peonies. The analysis of morphogenetic processes during microclonal propagation of lilac cultivars demonstrates well-defined correlation between susceptibility of this culture to mineral mixture of nutrient medium and plant genotype. Rose cultivars from different garden groups keep high growth capacity during 12 subculturing cycles on Murashige Skoog medium (MS) supplemented with 0.5 mg/l BAP. For all culturing tree-peonies cultivars Woody Plant Medium (WPM) with double content of Ca2+ ions and total exception of Cl- ions turns out to be more suitable. The opportunity of 10 lilac cultivars and 4 rose cultivars preservation in slow growth cultures was appreciated. The correlation between long-term cultivation in low temperature and genotype of ornamental plants cultivars was shown. Thus, 18 ºС turns out to be suitable for creation of slow-growth collection of all studied rose cultivars, and 14 ºС – only for 'Nina Weibull'. Maintaining of lilac microshoots at 10 ºС during 5 months practically did not act negatively on their viability.

Comparative transcriptome analysis of vegetative apices of Syringa vulgaris L. during physiological rest or in phase of active growth in vivo and in vitro were carried out.For transcriptome analysis the two type of lilac's shoots were used: (1) the aseptic culture of Syringa vulgaris L. shoots cultivated in the lab since 2008, (2) the adult plants growing in the open ground of MSU Botanical Garden.For experiment the aseptic microshoots were precultivated under slow-growth culture condition during 270 days after then apexes of one half of shoots were cutted and fixed in RNA-later.The remaining shoots were transferred to normal condition and growing for 28 days.Likewise the vegetative apices of adult S. vulgaris shrubs were collected under physiological rest (in winter) and from active growth (in springtime).The total RNA was purified with RNeasy Plant Mini Kit (Qiagen) from 20 mg of each fixed samples.The libraries were prepared using NEBNext ® Poly(A) mRNA Magnetic Isolation Module and NEBNext ® Ultra RNA Library Prep Kit for Illumina (NEB) and sequenced using HiSeq 2500 System.Reference transcriptome was assembled by Trinity, transcript quantification were made by Salmon and differential expression analysis were conducted using edgeR.A pairwise comparison of samples showed different level transcripts of two β-glucosidase isoforms, five superoxide dismutase isoforms, four peroxidase isoforms and three xyloglucan xylo glucosyltransferase isoforms in slow-growth condition in vitro vs. physiological rest lilac's plant apices in vivo.And different level transcripts of seven superoxide dismutase isoforms, three β-glucosidase isoforms and cytochrome p450 isoforms in lilac's shoot apices of active growth plants in vivo vs. in vitro.

Long-term conservation of plants in vitro means setting up conditions in which plants slow down their growth, which reduces the frequency of subculture needed to keep the material alive.Fall of cultivation temperature is frequently used for preservation of ornamental plants' cultures and of lilac's cultivars as well.For a better understanding of processes in in vitro culture, a comparative transcriptome analysis of vegetative apices of Syringa vulgaris L. during dormancy or in the phase of active growth in vivo and in vitro was carried out.A pairwise comparison of samples showed that a decrease in the temperature of lilac's microshoot cultivation down to +10 °C leads to the formation of a response similar to the response to oxidative stress.The changes in gene expression similar to such stress response persist within active shoots growth in sterile culture after their transfer to standard cultivation conditions (+22 °C).

In the article the results of studies on adventitious roots formation in microshoots of 2 lilac varieties are presented. The conditions for the induction of rhizogenesis in microshoots in sterile culture were worked out; advantage of indolebutyric acid was showed.