Lingonberry exobasidium (Exobasidium vaccinii)Systematics:
- Department: Basidiomycota (Basidiomycetes)
- Subdivision: Ustilaginomycotina ()
- Class: Exobasidiomycetes (Exobasidiomycetes)
- Subclass: Exobasidiomycetidae
- Order: Exobasidiales (Exobasidial)
- Family: Exobasidiaceae (Exobasidiaceae)
- Genus: Exobasidium (Exobasidium)
- Species: Exobasidium vaccinii (Lingonberry Exobasidium)
Lingonberry exobasidium (Exobasidium vaccinii) grows from July to autumn in coniferous forests on lingonberry leaves and its young shoots, on a stem, less often on flowers.
Lingonberry exobasidium (Exobasidium vaccinii) is found very often in almost all taiga forests to the northern border of the forest in the Arctic. At the beginning or middle of summer, the leaves, and sometimes young stems of lingonberry, are deformed: the infected areas of the leaves grow, the surface of the area on the upper side of the leaves becomes concave and becomes red in color. On the underside of the leaves, the affected areas are convex, snow-white. The deformed area becomes thicker (3-10 times in comparison with normal leaves). Sometimes the stems are deformed: they thicken, bend and turn white. Flowers are occasionally affected. Under a microscope, it is easy to detect large changes in the structure of leaf tissue. The cells are noticeably larger than normal size (hypertrophy), they are larger than normal. There is no chlorophyll in the cells of the affected areas,but in the cell sap a red pigment appears - anthocyanin. It gives the affected leaves a red color.
Between the cells of the lingonberry, fungal hyphae are visible, there are more of them near the lower surface of the leaf. Thicker hyphae grow between epidermal cells; young basidia develop on them, under the cuticle. The cuticle is torn, discarded in pieces, and on each mature basidium 2-6 spindle-shaped basidiospores are formed. From them, a delicate frost-like white coating appears on the underside of the affected leaf. Basidiospores, falling into a drop of water, soon become 3-5-cell. From both ends, the spores grow along a thin hypha, from the ends of which small conidia are lacerated. They can, in turn, form blastospores. Otherwise, those basidiospores germinate, which fall on young lingonberry leaves. The hyphae that appear during germination penetrate through the leaf stomata into the plant, and mycelium is formed there.After 4-5 days, yellowish spots appear on the leaves, and after another week, the disease of lingonberry has a typical picture. Basidium is formed, new spores are released.
The full development cycle of Exobasidium vaccinii takes less than two weeks. Lingonberry exobasidium (Exobasidium vaccinii) is an object and cause of controversy for many generations of mycologists. Some scientists see in exobasidiomycetes a primitive group, which confirms the hypothesis of the origin of hymenomycetes from parasitic fungi; therefore, these fungi are presented in their systems in an independent order ahead of all other hymenomycetes. Others, like the author of these lines, consider exobasidial fungi as a highly specialized group of fungi, as a lateral branch of the development of saprotrophic primitive hymenomycetes.
Thus, a large theoretical question about the origin of many thousands of species of higher fungi is connected with the solution of a particular question about the taxonomy of exobasidials. Another question, also connected with major theoretical problems, remained controversial. It has long been known that Lingonberry Exobasidium (Exobasidium vaccinii) grows on blueberries, cranberries, bearberry, andromeda and other heathers. This is all one species or a whole complex, albeit closely related, but independent highly specialized species.
The fruit body of Exobasidium vaccinii is absent. First, 5-7 days after infection, yellow-brownish spots appear on top of the leaves, which turn red after a week. The spot occupies part of the leaf or almost the entire leaf, from above it is pressed into a deformed leaf 0.2-0.3 cm deep and 0.5-0.8 cm in size, raspberry-red (anthocyanin). Below the leaf is a thickened bulge, a tumor-like outgrowth 0.4-0.5 cm in size, with an uneven surface and with a bloom of white (basidiospores).
Dense, fleshy, with a faint powdery odor, white, light.
With other specialized species of Exobasidium: blueberries (Exobasidium myrtilli), cranberries, bearberry and other heathers.
Refers to inedible parasitic fungi.