Forster, B.; Knizek, M.; Grodzki, W. (eds.) 1999: Methodology of Forest Insect and Disease Survey in Central Europe.
Proceedings ofthe Second Workshop ofthe IUFRO WP 7.03.10, April20-23, 1999, Sion-Chateauneuf, Switzerland.
Birmensdorf, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) 211-214.
DISTRIBUTION OF HETEROBASIDION ANNOSUM IN UKRAINE M.M. Sukhomlyn
Donetsk State University, 46 Shchorsa st., Donetsk 340050, Ukraine
The total area of wood fund of Ukraine makes 9,94 mln ga and is the least in Europe, following Moldavia (Hensiruk, 1994). Territory of Forest lands is 14,3 % (in majority of steppe regions does not exceed 1,9-4,8 % ), though an optimum level of forest lands is considered by experts as 19%. The woods are situated in the territory of Ukraine very nonuniformly. The greatest concentration of them is in the Ukrainian Carpathians ( 40,5 % of areae of all region), Crimean mountains (32 %) and in Polesie (26, 1 % ).
Now degree of forest lands and nonuniformity of location of wood resources in the territory of Ukraine is a result of various natural environments and influence of economic activity of people for a long historical period. So, from 1814 to 1914 the areas of woods of Ukraine has decreased by 30,5% due to elimination. In some industrial places annually from the polluted atmosphere up to 450-500 t/KM2 of soot and dust are accumulated in the air. On 1 ga of a fur- tree wood the needles accumulate 32 t of a dust, pine - 36, and beech - 68 (Hensiruk, 1994 ).
The significant part of woods has become inaccessible as a result of Chemobyl tragedy. 3,5 mln ga of woods are polluted with radionuclides after Chemobyl catastrophe that is 70 % of all polluted territory of Ukraine. 1,6 mln ga, from inspected 4 m1n ga of woods of State wood fund have a density of contamination of a ground by a cesium 13 7 more than 1 Ki/KM2 (Kaleinyk, 1996).
In recent years the deterioration of a condition of woods in Ukraine is noted.
Wood protection from the diseases caused by wood-attacking fungi is one of the effective measures on saving wood systems.
The main reason of sharp weakening and dying off of the trees of coniferous breeds is effect of Heterobasidion annosum (Fr.) Bref.
H. annosum is a constant component of all coniferous woods in Ukraine. At natural conditions its harmfullness is insignificant, together with other saprothrophic fungi the fungus destroys wood of stumps and promotes it mineralization. However under certain ecological conditions the fungus strikes mainly pure coniferous plantings, causes their pathological defection, considerably exceeding the natural one and resulting in mass loss.
In Carpathians and Pricarpatian regions the Heterobasidion annosum strikes mainly fur-tree · cultures, but can be found and in natural plantings. Most of hotbeds occur in humid and fresh types of growing locations conditions in pure thick forest over 20 years old, in natural plantings from 40-60 years. The centers of a strong degree of effect more often occur in Pricarpatian region, and the intensity of a effect decreases with height. In the highlands of Carpathians the hotbeds are usually formed both in wood cultures, and in natural plantings, located near the places of running and pasturing of cattle.
All the region of Western Polesie is subject to epiphytotia of illness. Practically all the cultures, in which the sharing of a fur-tree over 20 years old is more than 50 % created in fresh oak forests are the acting hotbeds of H. annosum with a strong degree of effect.
The hotbeds of H. annosum in pine plantings are most widespread in flat regions of West of Ukraine. Pathogen, as a rule, strikes wood cultures, which by 15th -20th year have not acquired natural resistance in connection with a discordance of conditions of location with biological- ecological properties of breeds, excessive density of growing, delayed performance of cutting of a leaving, which result
in
poor development of root systems of trees. The factors mentioned show more in too dense monocultures on the old-arable lands.211
In most cases direct reason of a pine-tree drying in the hotbed of H. annosum were the stems wreckers . Xylophages occupy, as a rule, physiological by weak trees, frequently even without external indications of weakening, and cause their drying off.
One from mandatory directions among phytopathologist of all the world in the research of the dangerous pathogen of coniferous breeds of the fungus H. annosum is discovery of availability of the intersterility groups in its population (Capretti et al., 1994). Long ago mycologists came across the problems of species, which do not differ by morphological features and which do not cross between each other. They are called that twin species or groups of intersterility.
The simple and rapid methods for the identification of the intersterility groups are yet unknown now. Therefore their distribution at H. annosum has not been well studied even in Europe and in Northern America, and almost nothing is known about intersterility groups of H. annosum outside those continents: Central Asia, Caucasus, Central Asia, Siberia, Far East and other parts of Northern Hemisphere. However already now there is a· general picture of distribution of intersterility groups of H.annosum in Europe and America (Korhonen et al., 1998).
Found in woods of Finland, Sweden, USA, Germany, Italy and other countries intersterility groups designated as S, P and F (Korhonen, 1978) are of interest to us for carrying out experiments on identification of intersterility groups of fungus found in the territory of Ukraine comparing to foreign isolates. The importance of such experiments, on the one hand, is explained by interest of the scientists for geography of pathogen distribution on eastern boundaries of Europe, which will enable to have an idea about a availability of the species. On the other hand, it will allow to make contact between the separate strains and groups in quite significant territory. Besides such researches are capable define allelic heterogeneity of the species. In addition to existence of the third intersterility group, which was found on the silver tree (Mitchelson, Korhonen, 1998) and also a certain attachment of the pathogen to a plant - host suggest a possibility of existence of new intersterility groups of H. nnosum. Moreover silver fir woods in Ukraine are not separated from the European ones and are an east boundary with silver fir woods in Central Europe.
The fruit bodies of pathogen were collected for studying of incompatibility. The prints of basidiospores from the fruit bodies were received. Hereinafter monosporous isolates from these basidiospores were received in culture. Crossing monosporous isolates from one fruit body in all possible combinations between each other on Petri dishes has allowed to divide them into two groups, which had the various factors of incompatibility as the fungus has a bipolar system of incompatibility. Distribution of alleles of the incompatibility factor among all collected fruit bodies was determined as a result of the crossing testers ( by 2 testers from each fruit body with opposite alleles of incompatibility). The formation of clamp connections on the mycelium in culture testified to the compatibility of cultures.
In our studies we used testers of Donetsk State University , testers of Plant Protection Laboratory ofUkrainian State University of Forestry and Wood Technology and homocarions from a collection of cultures of Research Institute of a Wood of Finland which Dr. K.Korhonen kindly give us.
As a result of studies carried out in 1985-1991 in the territory of Ukraine and Byelorussia it was possible to select two non-crossable groups of H. annosum, which were designated, as I and 11 groups. Due to crossing testers of the designated groups with testers of S and P of groups received from Finland the identity I and P of group and also 11 and S of group has been determined, as testers of I intersterility group formed clamp connections on mycelium with testers of P group and on the contrary the groups were not crossed with testers of S. In their turn testers of 11 intersterility group were crossed with monocarions of S, but did not form dycarion with testers of P group.
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Karpophores of the Ist intersterility group of the fungus are widely spread on a pine in purely pine and mixed pine-fur-trees plantings of Ukraine and Byelorussia, the single specimens were found on a fur-tree in the mixed pine-fur-tree plantings of the Minsk province (Byelorussia). Absolute absence of clamp connections in matting of cultures of groups I and S of and cultures of groups II and P testifies to full incompatibility between these groups.
Hereinafter two intersterility groups found in Ukraine named, as S and P of group, that would enable to compare them with those spread in Europe and in other parts of the world. Besides it was possible to identify founded hereinafter groups on the basis of founded in Ukraine testers and has enabled to characterize of distribution of intersterility groups of the fungus in the forests of Ukraine.
So, when matting testers of H.annosum distinguished finally from the fruit bodies from a pine, the fur-trees and one specimen with silver fir, have allowed to establish a relationship of these strains to appropriate intersterility group's on the basis of crossing them with a number of domestic testers. Geography of distribution of various intersterility groups of H. annosum in the territory of Ukraine is represented in Fig.1. The P group was found, both in Western, Central and in Eastern regions on pine. Representatives of S group can be found in Western regions on a fur-tree and silver fir.
Especially interesting, to our opinion are experiments on determination of the status of isolate collected from silver fir since F intersterility group was on silver fir early. In Ukraine isolates of the fungus from silver fir were not subjected to the genetic analysis concerning compatibility with isolates collected from a pine and fur-tree. However strain with silver fir has shown a membership to S to group and in our experiments the representatives ofF group were not found. Probably extreme east boundary of the silver firs plantings in Europe is emergency for F group, however only complete studies in this area can give a more exact answer, as interest concerning a attack on silver fir in Ukraine by groups H. annosum exists (Korhonen et al., 1998).
H. annosum is a polymorphic species, the process of species formation of which has not been finished, which attracts attention on the part of a taxonomy, as theoretical problems of intersterility acquire the increasing interest in recent years.
Though intersterility groups of H. annosum have been studied enough for a long time (Korhonen, 1978), until now they are not distinguished as separate biological species. It can be explained by the fact that they are not totally intersterile. Under laboratory conditions the intersterility groups with the greater or smaller frequency are crossed between each other (Stenlid, Karlsson, 1991 ). However under natural conditions intersterility is preserved completely (Otrosina et al., 1992), and formation of hybrids between them is rare event. From the taxonomic point of view such a situation is rather confusing, especially between European S and F groups, which demonstrate partial compatibility. In our studies partial crossmg between groups was not observed which can be explained by absence ofF group.
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