Nitrogen form influences the response of Deschampsia antarctica to dark septate root endophytes

Upson, Rebecca; Read, David J.; Newsham, Kevin K. ORCID: 2009 Nitrogen form influences the response of Deschampsia antarctica to dark septate root endophytes. Mycorrhiza, 20 (1). 1-11.

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Fungi with dematiaceous septate hyphae, termed dark septate endophytes (DSE), are common in plant roots, particularly in cold-stressed habitats, but their effects on their host plants remain obscure. Here, we report a study that assessed the effects of six DSE on the growth and nutrient balance of Deschampsia antarctica when plants were supplied with the same amount of nitrogen in organic (casein hydrolysate) or inorganic (ammonium sulphate) form under controlled conditions. After 60 days, the DSE, that had each been isolated from D. antarctica and which analyses of internal transcribed spacer and large subunit regions indicated were similar to members of the Helotiales (Oculimacula yallundae, Mollisia and Tapesia spp.) and unassigned anamorphic ascomycetes, typically had no effect on, or reduced by 33-71%, shoot and root dry weights relative to uninoculated controls when plants had been supplied with nitrogen in inorganic form. In contrast, the DSE usually enhanced shoot and root dry weights by 51-247% when plants had been supplied with organic nitrogen. In the presence of inorganic nitrogen, only sporadic effects of DSE were recorded on shoot and root nitrogen or phosphorus concentrations, whereas in the presence of organic nitrogen, three to six of the DSE isolates increased shoot and root nitrogen and phosphorus contents. Most of the isolates decreased the phosphorus concentrations of shoots and roots when plants had been supplied with nitrogen in organic form. Our data suggest that DSE are able to mineralise peptides and amino acids in the rhizosphere, making nitrogen more freely available to roots.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: BAS Programmes > Antarctic Funding Initiative Projects
ISSN: 0940-6360
Additional Keywords: Amino acids; Dark septate fungal endophytes (DSE); DS fungi; Helotiales; Inorganic and organic nitrogen; Peptides
NORA Subject Terms: Botany
Biology and Microbiology
Ecology and Environment
Date made live: 15 Nov 2010 13:40 +0 (UTC)

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