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Effect of P availability on temporal dynamics of carbon allocation and Glomus intraradices high-affinity P transporter gene induction in arbuscular mycorrhiza

Publiceringsår: 2006
Språk: Engelska
Sidor: 4115-4120
Publikation/Tidskrift/Serie: Applied and environmental microbiology
Volym: 72
Nummer: 6
Dokumenttyp: Artikel
Förlag: American Society for Microbiology

Sammanfattning

Arbuscular mycorrhizal (AM) fungi depend on a C supply from the plant host and simultaneously provide phosphorus to the colonized plant. We therefore evaluated the influence of external P on C allocation in monoxenic Daucus carota-Glomus intraradices cultures in an AM symbiosis. Fungal hyphae proliferated from a solid minimal medium containing colonized roots into a C-free liquid minimal medium with high or low P availability. Roots and hyphae were harvested periodically, and the flow of C from roots to fungus was measured by isotope labeling. We also measured induction of a G. intraradices high-affinity P transporter to estimate fungal P demand. The prevailing hypothesis is that high P availability reduces mycorrhizal fungal growth, but we found that C How to the fungus was initially highest at the high P level. Only at later harvests, after 100 days of in vitro. culture, were C flow and fungal growth limited at high P availability. Thus, AM fungi can benefit initially from P-enriched environments in terms of plant C allocation. As expected, the P transporter induction was significantly greater at low P availability and greatest in very young mycelia. We found no direct link between C How to the fungus and the P transporter transcription level, which indicates that a good C supply is not essential for induction of the high-affinity P transporter. We describe a mechanism by which P regulates symbiotic C allocation, and we discuss how this mechanism may have evolved in a competitive environment.

Disputation

Nyckelord

  • Biology and Life Sciences

Övrigt

Published
Yes
  • Microbial Ecology
  • ISSN: 0099-2240

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