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The taxonomic diversity of epiphytic myxomycetes depending on the height of the trunk on living woody plants in the arboretum of the Central Siberian Botanical Garden, Siberian Branch, Russian Academy of Sciences (CSBG SB RAS), has been studied. All samples of myxomycetes are obtained by cultivation by the method of moist chambers in the laboratory in Petri dishes. Sampling of bark from living woody plants is carried out at a height of trunks from 0 to 15 m from the soil level. The experiment involves nine species of introduced deciduous woody plants Fraxinus pennsylvanica, Prunus maackii, Populus alba, Salix alba, S. pentandra, S. triandra, Sorbus aucuparia, Tilia cordata, and Jungles mandshurica. As a result of data analysis, 51 species of myxomycetes are revealed. It is noted that the species composition of myxomycetes on the studied woody plants differs significantly from that on native tree species growing on the territory of the botanical garden. Two species of the genus Arcyria and Trichia new for science, 3 species new to Russia (Didymium clavodecus, D. ovoideum, and D. synsporon), and 18 species new for Novosibirsk Region have been identified. A description of species new to science is given; photographs of sporocarps, spores, and capillitium studied using light and scanning electron microscopy are provided; and a comparison with morphologically similar species is made. A change in the taxonomic composition of myxomycete communities depending on the height of the trunk is established. On the bark collected at the roots of trees, 25 species of myxomycetes have been identified; at a height of 1.5 m, 18; at a height of 5 m, 32; at a height of 10 m, 14; and, at a height of 15 m, 17. Representatives of the genus Perichaena are found at all heights, but the greatest species diversity is noted in the basal part, where seven species are noted, while species of the genus Didymium have the maximum species diversity (six species) at a height of 5 m, including three species new to Russia, noted only at this height. The distribution of the number of samples by height showed that the bark of living woody plants is most abundantly populated at a height of 5 m (72 samples) and at the root (50 samples). [ABSTRACT FROM AUTHOR]

Urban green spaces are known to be subjected to additional anthropogenic stress. Using native plants in monoculture, i.e., planting trees of the same species, may favour disease outbreaks and plant death. Non-native plants to be used in large cities for creating sustainable plantations are being searched for worldwide. Meanwhile, it is necessary to control plant pathogens in the variable conditions of the region and natural habitat. In Siberian cities, non-native European trees are used, and non-native Siberian plants are introduced in Belarus. This article reports long-term observations of foliar fungal pathogens attacking 21 woody plants (19 European, 2 Siberian) in Siberian and Belarusian cities. In both regions, 48 leaf fungal pathogens were detected, with powdery mildew fungi predominating in Belarus and leaf spotting fungi prevailing in Siberia. In both research regions, the greatest number of fungal species was found on Syringa vulgaris L. In Siberia, many pathogens were found on the non-native European plant Berberis vulgaris (9 species) and native plant Caragana arborescens Lam. (8 species). We have not detected the pathogens on European plants: Acer campestre L., Acer platanoides L., Euonymus europaeus L., Lonicera caprifolium L. in urban green areas in Siberia, while we have identified one to four foliar fungal pathogens on these plants in Belarus. To sum up: more pathogens were found on native plants in Siberia and Belarus; some leaf pathogen species (Sawadaea tulasnei (Fuckel) Homma, Erysiphe alphitoides (Griffon & Maubl.) U. Braun & S. Takam., Cladosporium syringae (Oudem.) Montem., Erysiphe syringae Schwein., Erysiphe palczewskii (Jacz.) U. Braun & S. Takam.) followed their host plants (Acer tataricum L., Syringa vulgaris L., Caragana arborescens Lam.) when introduced into new areas; and some local pathogens were also observed to spread to the non-native plants of closely related species. [ABSTRACT FROM AUTHOR]

The authors have investigated the diversity of Nitraria sibirica by the ISSR-PCR method in 22 natural populations of Altai krai, the Republic of Altai, and the Republic of Kazakhstan. When primer UBC-807 is used, the number of amplified DNA fragments is 16 and their sizes vary from 200 to more than 1000 bp. The number of polymorphic loci is 14 and their proportion is 87.5%. A high level of interpopulation differentiation is revealed for N. sibirica. The interpopulation component accounts for 68% of all variability. The Nei genetic distance (D) between samples within populations does not exceed D = 0.14. Interpopulation distances vary within D—0.11–0.50. In total, 14 variants of the genotype have been found which are divided into 2 groups: Siberian and Kazakhstan. The maximum genetic differences are recorded in Kazakhstan samples Nitraria from the Koktal population, which may be a consequence of the ecological and geographical differentiation of N. sibirica in the extra-arid conditions of the Ili Basin. [ABSTRACT FROM AUTHOR]

This article presents the results of 15-year observations of alien and native foliar fungal pathogens and woody plants in Siberian arboreta and urban ecosystems and discusses the possibility of using these data to determine how the pathogenic mycobiota of woody species was formed under Siberian conditions. In total, 121 species of pathogenic micromycetes affecting the leaves of woody plants in botanical gardens and city and belonging to 2 divisions, 14 orders, and 46 genera have been revealed. Most of these species belong to the Ascomycota division (86.8%). The Basidiomycota division is represented by fungi from the order Pucciniales. Among all observed pathogens, 21 species belong to powdery mildew fungi, 15 species belong to rust fungi, and 84 species represent anamorphic fungi. A study of 108 woody plant species growing in Siberian cities has revealed 101 species of leaf pathogens, while 158 woody plant species growing in arboreta have been inhabited by 105 pathogen species. All fungal species revealed during this study, except for three species (Mycopappus alni, Venturia acerina, and Phyllosticta westendorpii), have been observed in Siberia earlier. However, some fungus–host plant associations are apparently new to science, suggesting that complexes of cryptic species differing in their host range and geographic range may occur. The main sources for tree mycobiota formation in Siberia include the invasion of pathogens together with alien plant species, the transition of pathogens from native to alien plant species, the enhancement of a pathogenicity of saprotrophic fungi, and the expansion of fungi onto new hosts. The majority of pathogens (65−75% of the total number of revealed fungi) locate on native plants. Alien plants are infected mainly by (native) pathogens. Only eight pathogen species have been introduced in Siberia with alien plants; three of them originate from the Far East (Cercospora gotoana, Phyllosticta phellodendricola, and Erysiphe palczewskii), while five are of European origin (Cladosporium syringae, Phyllosticta vincae-minoris, Erysiphe syringae, Erysiphe alphitoides, and Erysiphe berberidis). In Siberia, the lateness of phenological phases of plants originating from mild climatic zones, may be favorable for the development of fungal pathogens, such as Erysiphe alphitoides, causing the powdery mildew of oak trees. [ABSTRACT FROM AUTHOR]

In this article, we report observations made during thirteen years on foliar fungal pathogens attacking European and Eurasian woody broadleaved species in Siberian arboreta and cities and discuss the possibility of using such data for detecting exotic pathogens that may represent a danger for European tree and shrub species, should these pathogens be introduced into Europe. A total of 102 cases of symptomatic infections (fungus-host plant associations) involving 67 fungal species were recorded on 50 of the 52 European and Eurasian woody plant species. All but four of the fungi found during the surveys were previously reported in Europe. However, 29 fungus-host plant associations are apparently new to science, suggesting that complexes of cryptic species differing in their host range and geographic range may occur. Seventeen percentage of associations were given a high damage score, that is, more than 50% of plant area was attacked, for at least some localities. In nearly half of the cases, fungus-host plant associations were found to be very frequent, that is, occurring every year and at all locations where the plant was inspected. A list of pathogen-host associations in Siberia deserving further investigation is provided, either because the pathogen is not yet recorded in Europe or because the pathogen-host association has not yet been reported, and the damage is high or, finally, because the damage and infestation level is unusually high in known associations. Further studies should involve molecular characterization of these foliar pathogens and their host range testing. [ABSTRACT FROM AUTHOR]

Pathogenic micromycetes developing on leaves of woody plants from urban ecosystems in the south of Western Siberia have been analyzed in the article. In all, 101 pathogenic species have been found. General regularities in the structure of micromycete complexes have been obtained for five cities in Siberia and various landscaped areas. [ABSTRACT FROM AUTHOR]