Open Ground Collections of Saint Petersburg Botanic Garden for the Benefit of Botanic and Environmental Education

Botanic gardens with their rich collections and scientific resources have a unique potential that attracts the attention of the society to the problems of preserving biodiversity, ensuring environmental education, conserving nature, providing leisure, serving the place for relaxation and entertainment. One of the oldest Botanic gardens of Russia is the Saint Petersburg Botanic Garden of the Komarov Botanic Institute of the Russian Academy of Sciences demonstrates the experience of utilizing the open ground collections for Botanic and environmental education. The experts share various aspects of interaction between a Botanic garden and its visitors. The paper provides examples of excursions and other forms of work on the open ground. The paper analyzes the experience of foreign colleagues related to the motivation for visiting Botanic gardens by different age and social groups. The authors provide data of sociological surveys of visitors and the analysis of their motives to visit the Saint Petersburg Botanic Garden in particular. It also shows the growth of interest in the open ground collections

Seed quality of Aristolochia macrophylla Lam. and A. manshuriensis Kom. in St. Petersburg

Background. The study and mobilization of natural flora species in botanical gardens allow the curators to save biological resources of useful plant species, and recommend them for urban landscaping. In the flora of Russia, one species of a woody vine from the genus Aristolochia L. is A. manshuriensis Kom.; it is included in the Red Data Book of Russia.Methods The material for the study was A. macrophylla Lam. and A. manshuriensis from the collection of the Peter the Great Botanical Garden maintained by the Komarov Botanical Institute of the RAS. Winter hardiness was assessed; plant height, stem diameter, and crown diameter were measured. The sizes and age are given according to the state of the plants in the fall of 2017. Seed quality was assessed with due regard to the approved guidelines. X-ray analysis of fruits and seeds was carried out using the methods developed for the use of microfocus radiography for seeds and fruits.Results. A. manshuriensis has been grown in the Peter the Great Botanical Garden since 1909. The first flowering was observed in 1918 and 1919, the first fruiting in 1924. Currently, plants of the third or fourth generation are present in the collection. A. macrophylla has been known in St. Petersburg since 1816. Over a 200-year period of introduction, only flowering was observed. For the first time, fruiting in this species was registered in 2007; since 2014, second-generation plants have been grown. Analysis of the seeds collected in 2016 and 2017 showed that they are viable and of high quality in both species of Aristolochia. These species are winter-hardy, demonstrate rapid growth, and may somewhat vary in the timeframe of the passage of main phenological phases in their seasonal rhythm of development.Conclusion. For laying out plantations, it is better to use seeds. A. macrophylla and A. manshuriensis are promising for wider cultivation and use in vertical landscaping

Pollen of <i>Pterocarya</i> (Juglandaceae) representatives from natural habitats and St. Petersburg environments

Background. Comparative palynomorphological studies of naturally occurring and introduced Pterocarya Kunth representatives reveal the taxonomic significance of pollen morphological features and pollen characters of cultivated plants. The quality of pollen material and the potential of the plants from the Botanical Garden of BIN RAS for introduction are characterized.Materials and methods. Pollen grains were investigated using light, confocal laser scanning and scanning electron microscopes. Fertility was assessed using the standard acetocarmine method.Results. Comparison of pollen morphology in cultivated and naturally growing plants of this genus was made for the first time. Pollen fertility of two cultivated species (Pterocarya rhoifolia Siebold et Zucc., and P. stenoptera DC.) was very high, generally over 90%. Fertility of P. fraxinifolia (Lam.) Spach grains varied from 28 to 73% in different years, which is a low or medium level of pollen quality. Morphologically, pollen grains of all 12 specimens from five taxa are flattened, medium sized, 21–45 μm in diameter, with 4–8 pores; pores are located mainly at or near the equator. The pores are round or oval, with a limbus. Exine is three-layered, thickened near the pore. The sculpture is microechinate. The low-fertile P. fraxinifolia specimen contains small pollen grains, as well as grains in tetrads and dyads. The data on the introduction of the genus in St. Petersburg are presented.Conclusion. The palynonomophological description is diagnostic for the genus Pterocarya. The Pterocarya pollen is well distinguishable from other wind-pollinated taxa; however, species identification by pollen for spore-pollen analysis is not practicable. Morphologically, the most diverse are the grains of the low fertile specimen P. fraxinifolia. The limited possibility of seed propagation of P. fraxinifolia is probably explained by low pollen fertility. The pollen quality of the introduced P. rhoifolia and P. stenoptera is high

PYRUS ZANGEZURA (ROSACEAE) AT SAINT PETERSBURG

Pyrus zangezura Maleev (Rosaceae) is a rare species representing the native vegetation of Armenia (Southern Transcaucasus). It was first described in 1936. P. zangezura has been cultivated at the Peter the Great Botanical Garden of the Komarov Botanical Institute (St. Petersburg, Russia) since 1949, where it has reached the height of 8,0 m. For many years, it was in its vegetative state. The first flowering was observed in 2016 (the plant entered the reproductive state). The first progeny from seed was obtained in April 2019. Fruit size was assessed for P. zangezura plants in the dynamics of their development. The studied plants of P. zangezura in the environments of St. Petersburg have demonstrated a high fruiting potential – on average, 109 flowers per 1 m of a shoot. Observations have shown that not all ovules in the opened flowers of P. zangezura are fertilized and produce fruits and seeds. A significant part of the opened flowers, a few days after the onset of flowering, dry up and fall off. On average, 7 fruits are set on 1 m of the shoot in P. zangezura. The reasons for the low flower setting may be variable: impaired pollination processes and insufficient fertility of pollen, underdevelopment of the flower morphological structures, or lack of pollinating insects due to adverse weather conditions. An X-ray analysis of the seeds from the harvests of 2016, 2017 and 2018 showed that the number of plump and fully developed seeds (grades IV and V) in fruits has been growing year by year. As an ornamental plant, P. zangezura may adorn any botanical garden, but it is also promising for urban landscaping, for example, in St. Petersburg. Even in the vegetative state, its elongated lanceolate glossy leaves make it appreciably different from the common P. communis L., and it is especially ornamental during flowering and fruiting. It is as winter-hardy as the common pear-tree, demonstrates resistance to diseases and pests, and may be of importance for breeding programs aimed at the development of resistant cultivars for the Northwest of Russia

Phage T4 SegB protein is a homing endonuclease required for the preferred inheritance of T4 tRNA gene region occurring in co-infection with a related phage

Homing endonucleases initiate nonreciprocal transfer of DNA segments containing their own genes and the flanking sequences by cleaving the recipient DNA. Bacteriophage T4 segB gene, which is located in a cluster of tRNA genes, encodes a protein of unknown function, homologous to homing endonucleases of the GIY-YIG family. We demonstrate that SegB protein is a site-specific endonuclease, which produces mostly 3′ 2-nt protruding ends at its DNA cleavage site. Analysis of SegB cleavage sites suggests that SegB recognizes a 27-bp sequence. It contains 11-bp conserved sequence, which corresponds to a conserved motif of tRNA TψC stem-loop, whereas the remainder of the recognition site is rather degenerate. T4-related phages T2L, RB1 and RB3 contain tRNA gene regions that are homologous to that of phage T4 but lack segB gene and several tRNA genes. In co-infections of phages T4 and T2L, segB gene is inherited with nearly 100% of efficiency. The preferred inheritance depends absolutely on the segB gene integrity and is accompanied by the loss of the T2L tRNA gene region markers. We suggest that SegB is a homing endonuclease that functions to ensure spreading of its own gene and the surrounding tRNA genes among T4-related phages

Learning to live together: mutualism between self-splicing introns and their hosts

Group I and II introns can be considered as molecular parasites that interrupt protein-coding and structural RNA genes in all domains of life. They function as self-splicing ribozymes and thereby limit the phenotypic costs associated with disruption of a host gene while they act as mobile DNA elements to promote their spread within and between genomes. Once considered purely selfish DNA elements, they now seem, in the light of recent work on the molecular mechanisms regulating bacterial and phage group I and II intron dynamics, to show evidence of co-evolution with their hosts. These previously underappreciated relationships serve the co-evolving entities particularly well in times of environmental stress

Mobile DNA elements in T4 and related phages

Mobile genetic elements are common inhabitants of virtually every genome where they can exert profound influences on genome structure and function in addition to promoting their own spread within and between genomes. Phage T4 and related phage have long served as a model system for understanding the molecular mechanisms by which a certain class of mobile DNA, homing endonucleases, promote their spread. Homing endonucleases are site-specific DNA endonucleases that initiate mobility by introducing double-strand breaks at defined positions in genomes lacking the endonuclease gene, stimulating repair and recombination pathways that mobilize the endonuclease coding region. In phage T4, homing endonucleases were first discovered as encoded within the self-splicing td, nrdB and nrdD introns of T4. Genomic data has revealed that homing endonucleases are extremely widespread in T-even-like phage, as evidenced by the astounding fact that ~11% of the T4 genome encodes homing endonuclease genes, with most of them located outside of self-splicing introns. Detailed studies of the mobile td intron and its encoded endonuclease, I-TevI, have laid the foundation for genetic, biochemical and structural aspects that regulate the mobility process, and more recently have provided insights into regulation of homing endonuclease function. Here, we summarize the current state of knowledge regarding T4-encoded homing endonucleases, with particular emphasis on the td/I-TevI model system. We also discuss recent progress in the biology of free-standing endonucleases, and present areas of future research for this fascinating class of mobile genetic elements

Introduction of Sorbocotoneaster pozdnjakovii Pojark. in the Peter the Great botanical garden

Pozdnyakov’s mountain ash Sorbocotoneaster pozdnjakovii Pojark. is a hybrid genus with a single species that arose from spontaneous hybridization of Cotoneaster melanocarpa Lodd. × rowan Sorbus sibirica Hedl. (Rosaceae), endemic to the flora of Russia. In the Peter the Great Botanical Garden Botanical Institute of the Russian Academy of Sciences it is known since 1953, from locus classicus of the natural provenance. The seed reproduction of the second generation was obtained for the first time in 2010. The germination ability was low 4–14 %. In natural conditions the species grows in sharply continental climate. There are cases of the rotting of plants soaking and destruction of plants from Phytophthora in the Saint-Petersburg’s the Peter the Great Botanical Garden at the end of the 1980’s. Under conditions of noticeable climate warming, it is necessary to do uninterrupted phenological observations, monitor the disease resistance, to develop agrotechnical cultivation maps

<i>CYDONIA OBLONGA </i> MILL. (ROSACEAE) AT THE PETER THE GREAT BOTANICAL GARDEN

20th century, common quince was considered not winter-hardy enough for the environments of the North-West of Russia. Cydonia oblonga Mill. was for the first time mentioned in the Catalogues of the Peter the Great Botanical Garden in 1793. It has been always present in the Garden's modern collection since 1949. The first flowering of common quince was noted in the late 1970s (after 20 years of cultivation), and in 2014 the first fruiting was recorded (65-year-old plants). The study of the quality of seeds has shown that in St. Petersburg's conditions they develop and almost ripen. However, for the time being the quality of seeds is insufficient to obtain seed reproduction. To increase seed quality cross-pollination is necessary. In North-Western Russia, quince has never been regarded as promising even for amateur cultivation, but it may become promising in case of further warming of the climate. Common quince is highly ornamental during its flowering period. It blossoms from late April to early May

Chamaecyparis obtusa in Peter the Great botanical garden

Species of the genus Cypress trees (Chamaecyparis Spach), family Cupressaceae – monoecious evergreen trees with a cone-shaped dense crown and aromatic resinous needles. In nature, they grow in East Asia (China, Japan, Taiwan) and North America; ornamental plants suitable for urban gardening and modern urban floristry. These plants look good in single, group and avenue plantings, especially in places with a suitable climate. They give valuable light, fine-grained, fragrant, hard and durable wood. The varietal wealth is so great – only 4 species have produced over 1500 modern cultivars. In culture, many varieties of Japanese selection are known, which have already proven themselves well in other countries. In most cases, cypress trees are suitable in areas with a maritime climate, mild winters and high humidity. Comparison with literature and archival data shows that in recent years and decades, against the background of climate warming, there has been a significant increase in the size of plants. Blunt cypress (Chamaecyparis obtusa (Siebold et Zucc.) Endl.), in the Peter the Great Botanical Garden of V. L. Komarov Botanical Institute, Russian Academy of Sciences has been known since 1870, it grown in the collection in different periods –the first mention from 1870 to 1898, then in the period from 1949 to 1977. It has been included in the modern collection of the arboretum since 2009. At the age of 14, it is a double-trunked tree 1.94 m high, with a trunk of 0.20 m. In 2018, seed production was observed for the first time. In 2021, seed offspring were obtained. Given the ongoing warming of the climate in St. Petersburg and increasingly favorable wintering conditions, blunt cypress has prospects for wider cultivation in the North-West of Russia and introduction into the modern range of gardens and parks in St. Petersburg as a new ornamental plant. For planting blunt cypress, one should choose a place protected from cold winds, without stagnant moisture, near groundwater, but a slightly shaded place is possible. In the summer, plants should be watered, this is especially important for young plants, preventing their earthen coma from drying out. In winter, during heavy snowfalls, it is useful to shake off the plants to avoid snow breakage