Ectomycorrhizal responses to organic and inorganic nitrogen sources when associating with two host species

Meghan L. Avolio, Amy Tuininga, J. D. Lewis, Michael Marchese

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

While it is established that increasing atmospheric inorganic nitrogen (N) deposition reduces ectomycorrhizal fungal biomass and shifts the relative abundances of fungal species, little is known about effects of organic N deposition. The effects of organic and inorganic N deposition on ectomycorrhizal fungi may differ because responses to inorganic N deposition may reflect C-limitation. To compare the effects of organic and inorganic N additions on ectomycorrhizal fungi, and to assess whether host species may influence the response of ectomycorrhizal fungi to N additions, we conducted an N addition experiment at a field site in the New Jersey pine barrens. Seedlings of two host species, Quercus velutina (black oak) and Pinus rigida (pitch pine), were planted at the base of randomly-selected mature pitch pine trees. Nitrogen was added as glutamic acid, ammonium, or nitrate at a rate equivalent to 227.5 kg ha-1 y-1 for eight weeks, to achieve a total application of 35 kg ha-1 during the 10-week study period. Organic and inorganic N additions differed in their effects on total ectomycorrhizal root tip abundance across hosts, and these effects differed for individual morphotypes between oak and pine seedlings. Mycorrhizal root tip abundance across hosts was 90 % higher on seedlings receiving organic N compared to seedlings in the control treatment, while abundances were similar among seedlings receiving the inorganic N treatments and seedlings in the control. On oak, 33-83 % of the most-common morphotypes exhibited increased root tip abundances in response to the three forms of N, relative to the control. On pine, 33-66 % of the most-common morphotypes exhibited decreased root tip abundance in response to inorganic N, while responses to organic N were mixed. Plant chemistry and regression analyses suggested that, on oak seedlings, mycorrhizal colonization increased in response to N limitation. In contrast, pine root and shoot N and C contents did not vary in response to any form of N added, and mycorrhizal root tip abundance was not associated with seedling N or C status, indicating that pine received sufficient N. These results suggest that in situ organic and inorganic N additions differentially affect ectomycorrhizal root tip abundance and that ectomycorrhizal fungal responses to N addition may be mediated by host tree species.

Original languageEnglish
Pages (from-to)897-907
Number of pages11
JournalMycological Research
Volume113
Issue number8
DOIs
StatePublished - 1 Jan 2009

Fingerprint

inorganic nitrogen
organic nitrogen
Seedlings
Meristem
Nitrogen
root tips
seedling
seedlings
Pinus
nitrogen
morphotype
Quercus velutina
Quercus
Fungi
fungus
fungi
pine barrens
Pinus rigida
phytochemistry
plant biochemistry

Keywords

  • Mycorrhiza
  • N deposition
  • Pine barrens
  • Pinus rigida
  • Quercus velutina

Cite this

Avolio, Meghan L. ; Tuininga, Amy ; Lewis, J. D. ; Marchese, Michael. / Ectomycorrhizal responses to organic and inorganic nitrogen sources when associating with two host species. In: Mycological Research. 2009 ; Vol. 113, No. 8. pp. 897-907.
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abstract = "While it is established that increasing atmospheric inorganic nitrogen (N) deposition reduces ectomycorrhizal fungal biomass and shifts the relative abundances of fungal species, little is known about effects of organic N deposition. The effects of organic and inorganic N deposition on ectomycorrhizal fungi may differ because responses to inorganic N deposition may reflect C-limitation. To compare the effects of organic and inorganic N additions on ectomycorrhizal fungi, and to assess whether host species may influence the response of ectomycorrhizal fungi to N additions, we conducted an N addition experiment at a field site in the New Jersey pine barrens. Seedlings of two host species, Quercus velutina (black oak) and Pinus rigida (pitch pine), were planted at the base of randomly-selected mature pitch pine trees. Nitrogen was added as glutamic acid, ammonium, or nitrate at a rate equivalent to 227.5 kg ha-1 y-1 for eight weeks, to achieve a total application of 35 kg ha-1 during the 10-week study period. Organic and inorganic N additions differed in their effects on total ectomycorrhizal root tip abundance across hosts, and these effects differed for individual morphotypes between oak and pine seedlings. Mycorrhizal root tip abundance across hosts was 90 {\%} higher on seedlings receiving organic N compared to seedlings in the control treatment, while abundances were similar among seedlings receiving the inorganic N treatments and seedlings in the control. On oak, 33-83 {\%} of the most-common morphotypes exhibited increased root tip abundances in response to the three forms of N, relative to the control. On pine, 33-66 {\%} of the most-common morphotypes exhibited decreased root tip abundance in response to inorganic N, while responses to organic N were mixed. Plant chemistry and regression analyses suggested that, on oak seedlings, mycorrhizal colonization increased in response to N limitation. In contrast, pine root and shoot N and C contents did not vary in response to any form of N added, and mycorrhizal root tip abundance was not associated with seedling N or C status, indicating that pine received sufficient N. These results suggest that in situ organic and inorganic N additions differentially affect ectomycorrhizal root tip abundance and that ectomycorrhizal fungal responses to N addition may be mediated by host tree species.",
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Ectomycorrhizal responses to organic and inorganic nitrogen sources when associating with two host species. / Avolio, Meghan L.; Tuininga, Amy; Lewis, J. D.; Marchese, Michael.

In: Mycological Research, Vol. 113, No. 8, 01.01.2009, p. 897-907.

Research output: Contribution to journalArticle

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