Egerton-Warburton, L , BassiriRad, H , Sehtiya, H , Lussenhop, J .
Uptake kinetics of organic and inorganic nitrogen in ectomycorrhizal Quercus seedlings.
Ectomycorrhizal (EM) tree species predominate in temperate forests where nitrogen (N) is generally considered to be the main growth- limiting factor. One dimension of EM functioning is the ability to access different soil N pools. Although there is evidence to suggest that EM fungi can gain direct access to organic N, only a small proportion of EM fungi have been tested to date. Such EM fungi were able to acquire amino acids and peptides, but some species appear to have a limited ability. These differences suggest that any change in N resources- including the physiological differences among EM fungi for N uptake and source, and those projected under the scenarios of anthropogenic N deposition- could feedback to influence plant growth and forest structure. We examined the uptake of organic (glycine) and inorganic (ammonium, nitrate) N in seedlings of Quercus alba and Q. rubra. Seedlings were each inoculated with one of six EM-forming species from the Basidiomycetes (Laccaria, Tricholoma, Cortinarius subg. Telamonia, Clavulina, Amanita) or Ascomycetes (Pezizales); these taxa included early (Laccaria, Pezizales) and late-successional EM fungi (Cortinarius, Tricholoma, Amanita). Nitrogen uptake kinetics were measured in hydroponic cultures. Depletion curves showed that in symbiosis, all EM fungi readily acquired glycine. Ammonium was acquired by certain EM, but nitrate uptake was higher in non-mycorrhizal than EM plants, suggesting that EM fungi may have a limited capacity to metabolize nitrate. Any increases in soil nitrate through atmospheric N deposition could therefore be detrimental to EM fungi and their host plants. We also detected differences in N uptake with EM colonization, and that Q. alba was more dependent on EM than Q. rubra. These factors could feedback to influence oak establishment and function by altering the efficiency of N uptake with changing N supply from the environment.
Log in to add this item to your schedule
1 - Chicago Botanic Garden, Institute for Plant Biology and Conservation, 1000 Lake Cook Rd, Glencoe, IL, 60022, USA
2 - University of Illinois, Biological Sciences, 845 W Taylor St, Chicago, IL, 60607, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Boulevard A/Hilton
Date: Tuesday, July 10th, 2007
Time: 3:30 PM