Dark septate endophytes - are they mycorrhizal?

Dark septate endophytes (DSE) are a miscellaneous group of ascomycetous ana morphic fungi that colonize root tissues intracellularly and intercellularl y. The limited selection of studies quoted here exemplifies the range of ho st responses to symbiotic DSE fungi. Like mycorrhizal associations, DSE ass ociations vary from negative to neutral and positive when measured by host performance or host tissue nutrient concentrations. This range of host resp onses is partially attributable to variation between different fungus taxa and strains. Similarly, hosts differ in their responses to a single DSE str ain. Experimental conditions may also govern the nature of the symbiotic as sociation. It is concluded that DSE are capable of forming mutualistic asso ciations functionally similar to mycorrhizas. If the variation in host resp onse to mycorrhizal fungi is considered to represent a continuum ranging fr om parasitism to mutualism, DSE symbiosis must be considered mycorrhizal, a t least under some conditions.Dark septate endophytes (DSE) are a miscellan eous group of ascomycetous anamorphic fungi that colonize root tissues intr acellularly and intercellularly. The limited selection of studies quoted he re exemplifies the range of host responses to symbiotic DSE fungi. Like myc orrhizal associations, DSE associations vary from negative to neutral and p ositive when measured by host performance or host tissue nutrient concentra tions. This range of host responses is partially attributable to variation between different fungus taxa and strains. Similarly, hosts differ in their responses to a single DSE strain. Experimental conditions may also govern the nature of the symbiotic association. It is concluded that DSE are capab le of forming mutualistic associations functionally similar to mycorrhizas. If the variation in host response to mycorrhizal fungi is considered to re present a continuum ranging from parasitism to mutualism, DSE symbiosis mus t be considered mycorrhizal, at least under some conditions.