The Dark Side Is Not Fastidious – Dark Septate Endophytic Fungi of Native and Invasive Plants of Semiarid Sandy Areas

Abstract

Dark septate endophytic (DSE) fungi represent a frequent root-colonizing fungal group common in environments with strong abiotic stress, such as (semi)arid ecosystems. This work aimed to study the DSE fungi colonizing the plants of semiarid sandy grasslands with wood steppe patches on the Great Hungarian Plain. As we may assume that fungi colonizing both invasive and native species are generalists, root associated fungi (RAF) were isolated from eight native and three invasive plant species. The nrDNA sequences of the isolates were used for identification. To confirm that the fungi were endophytes an artificial inoculation system was used to test the isolates: we considered a fungus as DSE if it colonized the roots without causing a negative effect on the plant and formed microsclerotia in the roots. According to the analyses of the ITS sequence of nrDNA the 296 isolates clustered into 41 groups. We found that 14 of these 41 groups were DSE, representing approximately 60% of the isolates. The main DSE groups were generalist and showed no specificity to area or season and colonized both native and invasive species, demonstrating that exotic plants are capable of using the root endophytic fungi of the invaded areas. The DSE community of the region shows high similarity to those found in arid grasslands of North America. Taking into account a previous hypothesis about the common root colonizers of those grasslands and our results reported here, we hypothesize that plants of (semi)arid grasslands share common dominant members of the DSE fungal community on a global scale.

Arabidopsis thaliana model system reveals a continuum of responses to root endophyte colonization

“…In contrast, Microdochium isolates colonized the accessions extensively, although these conclusions were based on fewer strains. As expected based on our (Mandyam et al 2010) and other (Knapp et al 2012) previous studies, the microscopic observations confirmed that Periconia forms melanized microsclerotia in the host cortex, and that Microdochium invariably produces chlamydospores. This supports the utility of the A. thaliana model for DSE symbioses.…”

“…Although many DSE fungi form similar morphological structures in the host roots (Jumpponen & Trappe 1998, Rodriguez et al 2009), they are taxonomically unrelated, vary in ecological or physiological functions and lead to variable host responses (Addy, Piercey & Currah 2005, Alberton, Kuyper & Summerbell 2010, Newsham 2011, Tellenbach, Grünig & Sieber 2011, Knapp, Pintye & Kovacs 2012. Our earlier studies in the tallgrass prairie concluded that while grasses overall tend to be colonized to a greater extent and respond more positively to DSE colonization, forbs also range from increased to no response to decreased biomass accumulation in their response to DSE fungi (Mandyam, Fox & Jumpponen 2012).…”

“…Our earlier studies in the tallgrass prairie concluded that while grasses overall tend to be colonized to a greater extent and respond more positively to DSE colonization, forbs also range from increased to no response to decreased biomass accumulation in their response to DSE fungi (Mandyam, Fox & Jumpponen 2012). DSE fungi are globally distributed and have been observed in more than 600 plant species across well over 100 plant families from diverse habitats, and the list of susceptible hosts increases as more studies survey plants for DSE (Jumpponen & Trappe 1998, Mandyam & Jumpponen 2005, Zhang et al 2011, Knapp et al 2012. However, thus far the model plant, Arabidopsis thaliana (L.) Heynhold., native to Europe and central Asia but now naturalized worldwide (Al-Shehbaz & O'Kane 2002), has not been surveyed or tested for its ability to form these common symbioses.…”

Invasive plants affect arbuscular mycorrhizal fungi abundance and species richness as well as the performance of native plants grown in invaded soils

“…This pattern reflects the general fungal abundance in soils under study as revealed by PLFA analysis (Stefanowicz et al 2016). Knapp et al (2012) found that the same dark septate endophyte isolates were detected from the roots of both alien and native plants in Hungary, supporting the hypothesis that this group of fungi has a wide host range. However, their effect on alien plants and potential role in their invasions remain to be investigated.…”

Diversidad, ecología e importancia potencial de los hongos endófitos septados obscuros en México

“…El término endófi to se utiliza para defi nir aquel microorganismo que habita dentro del tejido vegetal sin causar ningún daño aparente Knapp et al, 2012); este es el caso de los DSE que han sido encontrados dentro de raíces de diversas especies vegetales pertenecientes tanto a gimnospermas como a angiospermas . Algunos DSE se han identifi cado como los anamorfos de hongos ascomicetos, que en dicho estado producen conidios o son estériles y colonizan las raíces vivas de algunas plantas sin causarles un daño aparente o un desorden tisular Jumpponen, 2001).…”