Synopsis of the macrofungi (Basidiomycota) on wood of fruit trees in the Central Black Earth Region of Russia

Aim. To summarise and analyse data on the species diversity, distribution and substrate spectra of wood-inhabiting basidial macromycetes growing on fruit trees in the Belgorod, Voronezh, Kursk, Lipetsk, Oryol and Tambov Regions.Material and Methods. The work involved a critical examination of literature sources, LE, OHHI, and VU herbaria. We undertook field researches in 2019-2020, identified specimens collected based on light microscopy techniques and isolated the basidial fungi in a pure culture.Results. Data on 97 species of basidial macrofungi from 68 genera associated with Malus, Pyrus and Prunus wood in the Central Black Earth Region are summarised. Antrodia serpens and Ceriporia torpida are newly known to Russia. 65 new dikaryot-ic strains for 22 species of Agaricomycetes have been introduced into the LE-BIN. A total of 65 species are associated with Malus, 34 species with Pyrus and 29 species with Prunus. Five species (Lyomyces crustosus, Stereum hirsutum, Trametes hirsuta, T. ochracea and T. versicolor) grow on all three genera of host. These species specialise in fruit trees include Sarcodontia crocea and Phellinus pomaceus.Conclusion. Pathogenic activity has been clearly observed for 32 species of fungi found on trunks and branches of living trees, causing necrosis and trunk rot. Furthermore, it is recommended that regular phytopathological monitoring of orchards should be carried out, taking the group of xylotrophic fungi into account.


INTRODUCTION
Wood-decaying basidial fungi are crucial components in forest ecosystems. These organisms also play an important role in agricultural lands, as they induce necrosis and rotten plant diseases that lead to weakening, withering, suppression of flowering or death of trees. As a result, there is a decrease in yields, which has a negative impact on orchard productivity and in extreme cases may require the re-establishment of fruit plantations. Orchards, as monoculture stands, are particularly threatened by fungal phytopathogens: this situation is currently intensified by increasing global plant trade and the effects of climate change [1].
Russian phytopathological studies on agricultural plants generally focus on diseases caused by micromycetes [2; 3], while among polypores which cause trunk rot only common or particularly dangerous species are mentioned [4][5][6]. A similar situation also exists in the foreign literature where there are many investigations related to microfungi -endophytes and phytopathogens, for instance, [7][8][9]. At the same time, only a few publications are known which study the species diversity of Agaricomycetes associated with the wood of fruit trees [10][11][12]. The species of basidiomycete macrofungi that develop on fruit trees are often listed in more general studies [13; 14].
The total number of basidial fungi species growing on the wood of fruit trees can be estimated as approximately 200. In particular, the monograph "Poroid fungi of Europe" [15] contains data on findings of 110 species on Malus, Pyrus and Prunus wood. On the scale of the former USSR, the most comprehensive list of fungi on fruit cultures (78 species of higher basidiomycetes) can be obtained from the monograph of I. S. Popushoy [4]. Special studies of corticioid fungi on the wood of fruit trees in Belarus were undertaken by E. O. Yurchenko, who identified 58 species developing on Malus [16; 17].
In Russia, targeted researches to reveal the species diversity of macrofungi on fruit trees were undertaken in Krasnodar Territory [18; 19], Belgorod [20], Ryazan [21], Orenburg Regions [22]. However, similar investigations have not been done for most regions of European Russia.
The Central Black Earth Region (CBER), also known as the Central Chernozem Region or Chernozemie (the literal meaning of chernozem is a black-coloured soil containing a high percentage of humus) is one of the most important Russian agricultural regions. Belgorod, Kursk, Lipetsk, Oryol, Tambov, and Voronezh Regions are considered to be sectors of the CBER. Orchard agrocoenoses are widely represented here, including both large horticultural plantations and numerous private homestead plots of seed and stone fruit trees and shrubs.
In the 1990s, large areas of orchards lost proper horticultural and phytosanitary care, which led to a significant deterioration of fruit trees and the spread of a special group of phytopathogenic fungi -wood-decaying, or xylotrophic, Agaricomycetes. The focus of phytopathologists is often omitted in the study of wooddestroying fungi which also cause pathogenesis in fruit trees. The development of xylotrophic fungi is a definitely more prolonged process, resulting in chronic trunk rots [23], mainly associated with the pathogenic activity of certain species of aphyllophoroid fungi.
At the same time, there are no detailed summaries for the CBER regions on xylotrophic species of basidial macrofungi on fruit trees, including the principal ones -Malus domestica Borkh., Pyrus communis L., Prunus cerasus L. and P. domestica L.
Special investigations of poroid fungi, including polypores in orchards, were carried out in the CBER at the beginning of the 20 th century [24], which laid the basis for monitoring this group of phytopathogens. In subsequent years, data on the distribution of fungal pathogens in trunk and root rot of fruit trees have been extremely scattered in the literature, mainly as a result of studies of fungal species diversity in certain regions in different types of habitat [25][26][27].
The aim of this study was to summarise the available data and results of our own field research on basidial macrofungi on fruit trees in the CBER, to determine the species diversity and to reveal the key features of their distribution and ecology.
ecodag.elpub.ru/ugro/issue/current bacterial contamination. Dikaryotic strains were deposited in the Komarov Botanical Institute Basidiomycetes Culture Collection (LE-BIN, St. Petersburg, Russia) [47] and are stored using the subculture method, the disk method (in distilled water at 4°C) and the cryopreservation method at −80°C [48]. Identification of fungi, as well as macro-and micromorphological features of isolates were characterized by cultural and morphological parameters using common method and terminology [49]. Notes were made for every species on AW media: the color, general aspect, growth rate and growth mode of the hyphae, the presence/absence of asexual reproduction structures, particular smell. The growth of strains was characterized by the radius of the colony (mm) by 7, 14, 21 and 28 days, estimating the growth rate by the rate of cup overgrowth: fast growth (F) -1 week, medium (M) -2-3 weeks and slow (S) -4 weeks or more. Microscopic plates were analyzed with an Axio Imager A1 (Carl Zeiss, Germany) microscope.

RESULTS
An annotated list of basidial macrofungi species that develop on the wood of fruit trees in the CBER is presented below. The collection and identification of specimens was carried out by the authors, unless otherwise stated. Classification of taxa of above a genus level has been adopted in accordance with the current system of Basidiomycota [50].
ECOLOGY: the species is a saprotroph on deciduous wood causing a white rot, and it is extremely rare that the species can be found on living trees. We collected the specimens of C. calolepis on fallen branches and on a living trunk of Malus domestica. In the CBER there known findings of this species on Acer spp. and Populus tremula.  13.08.1912 [30]. The species is common and widely distributed in the CBER.
ECOLOGY: Ch. purpureum is a pathogen of deciduous trees, continuing to grow as a saprotroph after the death of the host. It rarely grows on coniferous wood. The species infects living trees damaged by frost and develops a characteristic change in the leaf epidermis called «silver leaf» [3; 51]. It was recorded on living branches and trees of Malus domestica and Prunus domestica. In the CBER this species also occurs on Acer negundo, Alnus glutinosa, Betula pendula, Populus tremula, Quercus robur, Salix sp. and Tilia cordata.  [41].
ECOLOGY: the species is a lichenicolous fungus, growing on the bark of a wide range of deciduous trees over the films of epiphytic algae and talli of different lichens. It was recorded on a fallen trunk of Prunus spinosa. In the CBER A. arachnoidea is also known only in Lipetsk Region on lichens on Acer negundo, Acer platanoides and Quercus robur [44].    -The central part of the colonies is coloured yellowish-brown; colony growth area remains white. Reverse dark brown but area under the centre of a colony's growth remains white. Growing colony edge is raised and is thick and dense, fringed, consisting of randomly growing hyphae. Outline colonies is wavy. Mycelial mat dense, tall, clear-zone, ragged, uneven, woolly, has a cotton-like texture. The colony has a crustose texture with age: hyphae forming a solid, hard dark brown crust. It has no special odour. Growth rate -S. Hyphal system monomitic. Aerial hyphae d 1.5-2.9 µm. Submerged hyphae up d 3.5 to 4.5 µm, sometimes with swellings.

BOLETALES
ECOLOGY: Ph. alni is a pathogen on deciduous trees. It causes a white rot. According to our data, this species ecodag.elpub.ru/ugro/issue/current occurs on living Malus domestica. In the CBER this species is recorded only on Alnus glutinosa. All specimens of Ph. pomaceus collected from Malus domestica were reidentified as Ph. alni according to Tomšovský et al. [52] and our data of molecular study (unpubl.).
Phellinus pomaceus (Pers.) Maire (=Ph. tuberculosus Niemelä) - Fig. 1  domestica. -The central part of the colonies is coloured yellowish-brown, colony growth area remains white. Reverse unchanged (in some strains reverse dark brown un-der the centre of the colonies). Growing edges of colonies range from flat, thin and transparent to raised, thick and dense, fringed, consisting of feathery hyphae. Mycelial mat dense, tall, unclear-zone, ragged, uneven, woolly, has a cotton-like or woolly texture. It has no special odour. Growth rate -M. Hyphal system monomitic. The mycelium consists of straight, smooth, sometimes tortuous, hyphae 2.6-6.1 μm in diameter with widely spaced septa, and thin hyphae d (1.2) 2.2-4.0 µm wide, straight and curved, occasionally anastomosing. Some hyphae are thickened with pigmented pale yellow to ochre rusty walls.
ECOLOGY: Ph. pomaceus is a common pathogen of Prunus trees, causing a white rot. According to our data this species occurs on living and dry standing Prunus armeniaca, P. cerasifera, P. cerasus, P. domestica, P. insititia and P. spinosa mostly at the base of branches. In CBER the species also occurs on Prunus padus [34].
Also, this species occurs on living trees of Malus domestica. According to Tomšovský et al. [52] these findings should be attributed to Ph. alni. Our investigations (this study, see above) confirm this idea.
Oxyporaceae Oxyporus corticola (Fr.) Ryvarden - Fig. 1   -The aerial mycelium is white or creamy (with age can become from dark-creamy to lemon-yellow and pink orange). Reverse unchanged (less often bleached). Growing colony edge pressed. Outline of colonies ranges from fringed (sometimes broken) to wavy and occasionally smooth. Mycelial mat most commonly has an approximately zonal (sometimes immersed) development. The colony most often has a floccose or floccose-cottony texture with small hyphal tufts, standing out from the agar (less often plumose texture). Odour is very intense; strong, sweetish-fruity. Growth rate -S (less often M). Hyphal system monomitic. The mycelium most commonly has thin-walled and branched hyphae (d -1.5 (4.0)-2.7 (6.0) μm) sometimes forming anastomosis. Branched generative hyphae, differentiated with septate and clamp connections, 3.5 (6.5)-4.5 (9.5) μm in diameter. Occasionally there were observed chlamydospores broadly ellipsoid (width Detailed descriptions of some strains are presented in Shakhova and Volobuev [53]. ECOLOGY: S. crocea is the most abundant pathogen of Malus trees. It was found on living and dry standing trees of Malus domestica. We also found it once on dry standing Pyrus communis [39]. In the CBER this species is also recorded only on Acer platanoides in Oryol Region [55]. Growing colony edge is appressed to raised, hyphae rather distant. Outline of colonies from smooth to wavy. The colony has a felty-farinaceous texture with cottony, which has become packed. Odour is very intense, mushroom-like (some strains are without any special odour). Growth rate -(M) F. Hyphal system dimitic. Generative hyphae (1.3) 1.5-3.5 (6.0) µm wide. Generative hyphae, differentiated with rare clamp connections, (4.5) 5.0-6.5 (9.5)  А.S. Bondartsev noted [24] that he had previously misidentified Aurantiporus fissilis from fruit trees in the Kursk Governorate as S. spumea. In our opinion, the above references of S. spumea actually refer to A. fissilis but unfortunately there was no possibility to study the specimens.  [45]. Oryol Region, Kolpnyansky District, Aleksandrovka, Pyrus sp., 05.10.2012, LE 292082 [37]. The species is common and widely distributed in the CBER.

RUSSULALES
STRAINS: LE-BIN 4337 (ex basidiospores), P. armeniaca. -The aerial mycelium is white becoming is orange or red to reddish-brown with age. Reverse unchanged. Growing colony edge is pressed. Mycelial mat is floccose: small hyphal tufts, standing out from the agar or from the aerial mycelium. It has no special odor. Growth rate -F. Hyphal system monomitic.

DISCUSSION
As a result of the analysis of available data, we obtained information on 97 species of basidial macrofungi from 68 genera associated with Malus, Pyrus and Prunus wood in the CBER. Thirty-two species were known before our own research started in 2008 [26]. Two species -Antrodia serpens and Ceriporia torpida -have been registered for the first time in Russia.
The first verifiable find of A. serpens from Oryol Region clarifies the eastern limits of the species distribution range in the European part of Russia. According to the recent research based on type material and using molecular tecnhiques [56], this species has for a long time been confused with close species of A. albida [15] -the latter is now synonymous with A. heteromorpha. The earlier records of A. serpens sensu Bondartsev [24] do not correspond to a modern understanding of the taxon and need to be revised for herbarium materials.
Ceriporia torpida is new to Russia and significantly extends the boundaries of the previously established range away to the south-east. Until the present study this species was only known from Finland (holotype, on dead Trametes sp. on Salix caprea) and the Czech Republic (fallen branch of Fagus sylvatica). The species has been described as a result of the taxonomic study of the Ceriporia purpurea group [57] and therefore the existing records of C. purpurea in the CBER need to be revised.
The maximum number of macrofungi species associated with the wood of fruit trees is known for Oryol Region -47 species, followed by Belgorod Region -40, Lipetsk Region -26, Kursk Region-24, Voronezh Region -7, and Tambov Region -2 species.
The largest number of fungal species (65)  Only two species were revealed in five regions (with the exception of Tambov Region) -Phellinus pomaceus and Sarcodontia crocea, the regularly occurring and the most important pathogens of Prunus spp. and Malus spp. respectively. Another four species were recorded in threefour regions: Phellinus alni, Schizophyllum commune and Stereum hirsutum -in four regions (except for Lipetsk and Tambov Regions), Peniophora cinerea and Trametes hirsuta -in three regions (except for Voronezh, Lipetsk and Tambov Regions). The proportion of species common to four of the most studied regions is shown in Fig. 2.
Five species of macrofungi grow on all three genera of fruit trees -Lyomyces crustosus, Stereum hirsutum, Trametes hirsuta, T. ochracea and T. versicolor. These are common, widespread species that are regularly found on the wood of different tree species in the CBER. The proportion of species common to the three discussed genera of fruit trees is shown in Fig. 3. ecodag.elpub.ru/ugro/issue/current Based on an analysis of the literature data that we could verify, among the fungi found during the studies Antrodia serpens, Candelabrochaete septocystidia, Ceriporia torpida, Hyphoderma mutatum, Phlebia rufa, Ph. tremellosa, Subulicystidium perlongisporum and Trichaptum biforme were noted for fruit trees for the first time in the European part of Russia. At the same time Candelabrochaete septocystidia and Subulicystidium perlongisporum are littleknown and rare species revealed in very few regions.
Most of the species registered are able to develop in a wide range of predominantly deciduous trees. The species that specialize in fruit trees include Sarcodontia crocea and Phellinus pomaceus.
Sarcodontia crocea is in most cases strictly associated with Malus, much less with Pyrus, and was only once recorded on Acer platanoides. The species was recorded in all the horticultural plantations we surveyed on live, drying and dry Malus trees, affecting up to 100% of all trees within an orchard: this makes it one of the highly dangerous pathogens causing significant yield losses to fruit trees due to drying and death.  . The share of macrofungi species associated with fruit trees, common to different plant genera Рисунок 3. Доля видов макромицетов, ассоциированных с древесиной плодовых пород, общих для различных родов плодовых пород Phellinus pomaceus is regularly recorded on living and dying plants of Prunus species, suggesting a narrow ecological niche. However, according to the literature, this spe-cies is also associated with other fruit trees from the genera Malus and Pyrus [58], or even a wider range of host plants -up to 20 genera [15]. Available results of molecu-I 93 lar studies [52] of the Phellinus igniarius s. l. species complex, to which this species belongs, also indicate the growth of Ph. alni and a single find of Ph. igniarius s. str. on Malus wood and the strict association of Ph. pomaceus with the genus Prunus. The results of the present study, which was carried out using molecular methods and ITS nrDNA analysis (unpublished data), confirm that in the CBER Ph. pomaceus develops exclusively on Prunus spp. trees, while Ph. alni grows on Malus spp.
The interesting finding published in the literature [33] is the discovery of Fistulina hepatica, which develops almost exclusively on Quercus robur, on Malus and Pyrus, although for this fungus it is known that in very rare cases it has also been found on other deciduous trees [15]. Unfortunately, we are not aware of the presence of specimens for this indication.
Pathogenic activity has been clearly marked for 32 species of fungi found on trunks and branches of living trees, causing necrosis and trunk rot. Five species were recorded on living branches and 31 species were registered on living trunks. Forty-two species were recorded on dry dead wood, including 29 species were recorded on dry branches in the crowns of living trees and 23 species on dry standing trunks. Only  A total of 48 species develop on dead wood (dead fallen branches, fallen trunks, stumps), of which 31 species develop exclusively on this type of substrate.
On fallen trunks and branches, species that are not saprotrophs have also been found by chance -the ecto-mycorrhizal Tomentellopsis echinospora (on Malus sp.) and Tomentellopsis pulchella (on Prunus spinosa) as well as the lichenicolous Athelia alnicola (on Prunus spinosa).