Regulation of genes involved in nitrogen utilization on different C/N ratios and nitrogen sources in the model ectomycorrhizal fungus Hebeloma cylindrosporum.
Nitrogen (N) utilization by ectomycorrhizal fungi is an essential aspect of their ecosystem function. N deposition changes both the N pools and the carbon/nitrogen (C/N) ratio of the substrates where ectomycorrhizal fungi are found, and it is important to understand how these changes affect the N forms used by ectomycorrhizal fungi. To overcome the difficulties of studying ectomycorrhizal fungi in situ, we investigated all known N genes in the model fungus, Hebeloma cylindrosporum in a culture study. In addition to studying the regulation of all known N utilization genes, we aimed to understand whether there are gene clusters that undergo similar regulation. Lastly we studied how C/N ratio, N transporter type, and N source affected relative gene expression levels. We grew the D2 strain of H. cylindrosporum on a range of inorganic and organic N sources under low, medium, and high C/N ratios. We found three gene clusters that were regulated in a similar pattern. Lastly, we found C/N ratio, N source and N transporter type all affected gene expression levels. Relative expression levels were highest on the high C/N ratio, BSA and diLeucine N sources, and inorganic N transporters were always expressed at higher levels than organic N transporters. These results suggest that inorganic N sources may always the default preference for H. cylindrosporum, regardless of both the N sources and the C/N ratio of the substrate.
University Bonn, IZMB, Transport in Ectomycorrhiza, Kirschallee 1, 53115 Bonn, Germany. meghan.avolio@yale.edu
Meghan
M
Avolio
Tobias
T
Müller
Anja
A
Mpangara
Michael
M
Fitz
Ben
B
Becker
Alexander
A
Pauck
Anja
A
Kirsch
Daniel
D
Wipf
D000596:Amino Acids / Q000378:metabolism; D001692:Biological Transport; D002244:Carbon / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D055364:Hebeloma / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008828:Microbiological Techniques; D005810:Multigene Family; D038821:Mycorrhizae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*
D000596:Amino Acids; D003470:Culture Media; D005656:Fungal Proteins; D002244:Carbon; D009584:Nitrogen