Nitrogen transfer in the arbuscular mycorrhizal symbiosis.
Nature
; 435(7043): 819-23, 2005 Jun 09.
Article
en En
| MEDLINE
| ID: mdl-15944705
ABSTRACT
Most land plants are symbiotic with arbuscular mycorrhizal fungi (AMF), which take up mineral nutrients from the soil and exchange them with plants for photosynthetically fixed carbon. This exchange is a significant factor in global nutrient cycles as well as in the ecology, evolution and physiology of plants. Despite its importance as a nutrient, very little is known about how AMF take up nitrogen and transfer it to their host plants. Here we report the results of stable isotope labelling experiments showing that inorganic nitrogen taken up by the fungus outside the roots is incorporated into amino acids, translocated from the extraradical to the intraradical mycelium as arginine, but transferred to the plant without carbon. Consistent with this mechanism, the genes of primary nitrogen assimilation are preferentially expressed in the extraradical tissues, whereas genes associated with arginine breakdown are more highly expressed in the intraradical mycelium. Strong changes in the expression of these genes in response to nitrogen availability and form also support the operation of this novel metabolic pathway in the arbuscular mycorrhizal symbiosis.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Simbiosis
/
Micorrizas
/
Nitrógeno
Idioma:
En
Revista:
Nature
Año:
2005
Tipo del documento:
Article
País de afiliación:
Estados Unidos