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Relationships between fungal uptake of ammonium, fungal growth and nitrogen availability in ectomycorrhizal Pinus sylvestris seedlings

Wallander, Håkan LU ; Arnebrant, Kristina LU and Anders, Dahlberg (1999) In Mycorrhiza 8(4). p.215-223
Abstract
Nitrogen deposition and intentional forest fertilisation with nitrogen are known to affect the species composition of ectomycorrhizal fungal communities. To learn more about the mechanisms responsible for these effects, the relations between fungal growth, nitrogen uptake and nitrogen availability were studied in ectomycorrhizal fungi in axenic cultures and in symbiosis with pine seedlings. Effects of different levels of inorganic nitrogen (NH4) on the mycelial growth of four isolates of Paxillus involutus and two isolates of Suillus bovinus were assessed. With pine seedlings, fungal uptake of N-15-labelled NH4 was studied in shortterm incubation experiments (72 h) in microcosms and in long-term incubation experiments (3 months) in pot... (More)
Nitrogen deposition and intentional forest fertilisation with nitrogen are known to affect the species composition of ectomycorrhizal fungal communities. To learn more about the mechanisms responsible for these effects, the relations between fungal growth, nitrogen uptake and nitrogen availability were studied in ectomycorrhizal fungi in axenic cultures and in symbiosis with pine seedlings. Effects of different levels of inorganic nitrogen (NH4) on the mycelial growth of four isolates of Paxillus involutus and two isolates of Suillus bovinus were assessed. With pine seedlings, fungal uptake of N-15-labelled NH4 was studied in shortterm incubation experiments (72 h) in microcosms and in long-term incubation experiments (3 months) in pot cultures. For P. involutus growing in symbiosis with pine seedlings, isolates with higher NH4 uptake were affected more negatively at high levels of nitrogen availability than isolates with lower uptake. More NH4 was allocated to shoots of seedlings colonised by a high-uptake isolate, indicating transfer of a larger fraction of assimilated NH4 to the host than with isolates showing lower NH4 uptake rates. Thus low rates of N uptake and N transfer to the host may enable EM fungi avoid stress induced by elevated levels of nitrogen. Seedlings colonised by S. bovinus transferred a larger fraction of the N-15 label to the shoots than seedlings colonised by P. involutus. Seedling shoot growth probably constituted a greater carbon sink in pot cultures than in microcosms, since the mycelial growth of P. involutus was more sensitive to high NH4 in pots. There was no homology in mycelial growth rate between pare culture and growth in symbiosis, but N uptake in pure culture corresponded to that during growth in symbiosis. No relationship was found between deposition of antropogenic nitrogen at the sites of origin of the P. involutus isolates and their mycelial growth or uptake of inorganic nitrogen (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
ammonium, ergosterol, extramatrical mycelium, Paxillus, Suillus
in
Mycorrhiza
volume
8
issue
4
pages
215 - 223
publisher
Springer
external identifiers
  • scopus:0032903368
ISSN
1432-1890
DOI
10.1007/s005720050237
language
English
LU publication?
yes
id
3dce0867-2dd2-4a5e-a946-1cfefe0dcc52 (old id 3560918)
date added to LUP
2013-03-08 11:43:29
date last changed
2017-01-01 04:19:53
@article{3dce0867-2dd2-4a5e-a946-1cfefe0dcc52,
  abstract     = {Nitrogen deposition and intentional forest fertilisation with nitrogen are known to affect the species composition of ectomycorrhizal fungal communities. To learn more about the mechanisms responsible for these effects, the relations between fungal growth, nitrogen uptake and nitrogen availability were studied in ectomycorrhizal fungi in axenic cultures and in symbiosis with pine seedlings. Effects of different levels of inorganic nitrogen (NH4) on the mycelial growth of four isolates of Paxillus involutus and two isolates of Suillus bovinus were assessed. With pine seedlings, fungal uptake of N-15-labelled NH4 was studied in shortterm incubation experiments (72 h) in microcosms and in long-term incubation experiments (3 months) in pot cultures. For P. involutus growing in symbiosis with pine seedlings, isolates with higher NH4 uptake were affected more negatively at high levels of nitrogen availability than isolates with lower uptake. More NH4 was allocated to shoots of seedlings colonised by a high-uptake isolate, indicating transfer of a larger fraction of assimilated NH4 to the host than with isolates showing lower NH4 uptake rates. Thus low rates of N uptake and N transfer to the host may enable EM fungi avoid stress induced by elevated levels of nitrogen. Seedlings colonised by S. bovinus transferred a larger fraction of the N-15 label to the shoots than seedlings colonised by P. involutus. Seedling shoot growth probably constituted a greater carbon sink in pot cultures than in microcosms, since the mycelial growth of P. involutus was more sensitive to high NH4 in pots. There was no homology in mycelial growth rate between pare culture and growth in symbiosis, but N uptake in pure culture corresponded to that during growth in symbiosis. No relationship was found between deposition of antropogenic nitrogen at the sites of origin of the P. involutus isolates and their mycelial growth or uptake of inorganic nitrogen},
  author       = {Wallander, Håkan and Arnebrant, Kristina and Anders, Dahlberg},
  issn         = {1432-1890},
  keyword      = {ammonium,ergosterol,extramatrical mycelium,Paxillus,Suillus},
  language     = {eng},
  number       = {4},
  pages        = {215--223},
  publisher    = {Springer},
  series       = {Mycorrhiza},
  title        = {Relationships between fungal uptake of ammonium, fungal growth and nitrogen availability in ectomycorrhizal Pinus sylvestris seedlings},
  url          = {http://dx.doi.org/10.1007/s005720050237},
  volume       = {8},
  year         = {1999},
}