Genetic diversity of fungi closely associated with common reed

. Variation in endophytic fungal diversity closely associated with roots, s tems and leaves of common reed (Phragmites australis) is reported here at s ites with different oxygen conditions. . Fungi isolated from surface-sterilized reed tissue were identified and ch aracterized by morphological and molecular methods including internal trans cribed spacer (ITS) sequence analysis from two dry and two flooded sites at Lake Constance (Germany). . Most isolates were ascomycetes, some basidiomycetes. There were differenc es in distribution between dry and flooded sites. Trichoderma sp. and Cylin drocarpon sp. were almost exclusively recovered from roots of reed growing at dry sites, whereas Microdochium sp. and Cladosporum sp. were more freque ntly found at flooded sites. The preference of Trichoderma sp. for drier si tes was confirmed by a nested PCR assay targeting the variable ITS region. . A diverse assemblage of endophytic fungi that differ in distribution betw een aerated and nonaerated soils is found in reed habitats. The rich mycofl ora associated with roots in completely anaerobic soils might depend on dow nward oxygen transport via an aerenchyma-based ventilation system.