Dark septate endophytes: a review of facultative biotrophic root‐colonizing fungi

Abstract

Dark septate root endophytes (DSE) are conidial or sterile fungi (Deuteromycotina, Fungi Imperfecti) likely to be ascomycetous and colonizing plant roots. They have been reported for nearly 600 plant species representing about 320 genera and 100 families. DSE fungi occur from the tropics to arctic and alpine habitats and comprise a heterogeneous group that functionally and ecologically overlaps with soil fungi, saprotrophic rhizoplaneinhabiting fungi, obligately and facultatively pathogenic fungi and mycorrhizal fungi. Numerous species of undescribed sterile and anamorphic taxa may also await discovery. Although DSE are abundant in washed root and soil samples from various habitats, and are easily isolated from surface-sterilized roots of ecto-, ectendo-, endo-and non-mycorrhizal host species, their ecological functions are little understood. Studies of DSE thus far have yielded inconsistent results and only poorly illustrate the role of DSE in their natural habitats. These inconsistencies are largely due to the uncertain taxonomic affinities of the strains of DSE used. In addition, because different strains of a single anamorph taxon seem to vary greatly in function, no clear generalizations on their ecological role have been drawn. This paper reviews the current literature on DSE and the ecology and discusses the need for and direction of future research.

Fungal Assemblages Associated with Roots of Halophytic and Non-halophytic Plant Species Vary Differentially Along a Salinity Gradient

“…A great component of the fungal diversity could be somewhat ascribed to dark-septate fungi (DSF), either by mycelial morphology or phylogenetic affiliation [43,45]. Most of them could be classified within the Pleosporales, as found in previous surveys in Mediterranean [43,44] or semiarid areas [9,[46][47][48][49].…”

Diversity and classification of mycorrhizal associations

“…Root endophytes with dark septate hyphae (called dark septate endophytes or DSE) are common in many habitats, and may provide benefits to their hosts ( Jumpponen & Trappe, 1998). These widespread root inhabitants are closely related to some ECM and ericoid fungi (Vrålstad, Schumacker & Taylor, 2002), but do not form mycorrhizal associations as defined by morphological criteria (Section IV).…”

Properties of the halophyte microbiome and their implications for plant salt tolerance

“…In addition to arbuscular mycorrhiza, some papers report the occurrence of so-called dark septate endophytes (DSEs). These root colonisers can be found in diverse habitats (Jumpponen and Trappe 1998) and have been detected in saline environments (Barrow and Aaltonen 2001;Sonjak et al 2009). These associations can be obligate: it is, for example, impossible to remove DSEs from the fourwing salt bush even if the plants have been grown from calli (Barrow et al 2004).…”