Ectendomycorrhiza

Ectendomycorrhiza , ectoendomycorrhiza ( EEM ) - one of the types of mycorrhiza , combines the signs of ectomycorrhiza and endomycorrhiza .

In many ways, it is similar to ectomycorrhiza: in the process of the emergence of symbiotic relations, a hyphal mantle (cover) and the Gartig network are formed . However, after the formation of the Gartig network, fungal hyphae penetrate the cells of the epidermis and peel of the plant.

This type of mycorrhiza is characteristic only for two genera of gymnosperms - pine and larch . Before the advent of molecular genetic methods, all imperfect fungi entering into ectendomycorrhiza were grouped under the name “strain E”. Subsequently, it was determined that most of them are species of the Ascomycetes genus Wilcoxina CSYang & Korf , 1985 : Wilcoxina mikolae and Wilcoxina rehmii . With twisted pine ( Pinus contorta ), ectendomycorrhiza forms Sphaerosporella brunnea . Wilcoxina and Sphaerosporella are representatives of the Pezizales order.

The ability to form similar mycorrhiza with conifers was found in two species from other orders - Cadophora finlandica and Chloridium paucisporum (known only by type specimen, should be assigned to another genus).

Many of the species that form ectendomycorrhiza are capable of forming ectomycorrhiza with plants of other gymnosperms and angiosperms.

Fungi that form ectendomycorrhiza cause dichotomous branching of short lateral roots (also observed with ectomycorrhiza), as well as the formation of clusters of short dichotomously branched roots in a plant. In studies of the Banks pine and Wilcoxina species, the formation of a thin hyphal mantle on short lateral roots was shown (at the early stages, hyphae also braid root hairs), then the formation of a single-layer Gartig network between epidermal cells and crust cells. Hyphae that penetrate the plant’s cells form a complex with the cell surrounding the cell nucleus. Hyphae are separated from the contents of the cytoplasm of cells due to the growth of the cell membrane. In the hyphae of the Gartig network and intracellular hyphae, there are numerous mitochondria and vacuoles with deposits (presumably of a polyphosphate nature), often Voronin's corpuscle .

Little is currently known about the benefits brought by fungi entering ectendomycorrhiza to plants. In pine and larch seedlings, ectendomycorrhiza is often found in disturbed areas. Perhaps the sugars supplied by the carbohydrate- destroying fungus are used by seedlings in the early stages of development, until they have the ability to get enough energy through photosynthesis . Species Wilcoxina produce siderophore ferricrocin , mycorrhiza with them can contribute to the survival of conifers with an increased concentration of heavy metals.