DSE association
DSE association (as derived from Dark Septate Endophytes) is a form of coexistence between a special type of filamentous fungi (DSE, typical representative is Phialocephala fortinii Wang & Wilcox) and a wide spectrum of higher plants. It is studied mainly on conifers (species of Pinus) and ericoid plants. It is supposed that the distribution of DSE fungi is limited only by extreme environmental conditions, DSE fungi are not present in waterlogged environments but were present for example in soil samples from Antarctic peninsula.
DSE association is probably the less studied and understood type of the symbiosis between roots of higher plants and fungi. For long period of time it was distinguished only as an example of weak parazitism of DSE fungi on plants. Recent studies however confirmed its bilateral utility, thus its mycorrhizal character, which can be on the other hand turned back to neutralism or weak parasitism by changing of environmental conditions. The plasticity of plants' reactions to DSE colonization makes DSE association an excellent model for the studies on plant-fungus interactions.
DSE fungi have thick, dark brown septate hyphae, which often form a dense sheath around colonized root. Single hyphae can form appressoria, penetrate root tissues and form typical anatomical structures (microsclerotia) inside cells or simply grow along stele.