Record ID No. |
546 |
Author(s) |
Olsson P.A., van Aarle I.M., Allaway W.G ., Ashford A.E ., Rouhier H. , 2002 |
Affiliation |
Lund University, Department of Microbial Ecology, Ecol Bldg,SE-22362 Lund, Sweden |
Title |
Phosphorus effects on metabolic processes in monoxenic arbuscular mycorrhiza cultures |
Source. Vol.(no):Page |
Plant Physiology. 130(3):162-1171p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Biochemistry |
Sub-subjects |
Phosphorus metabolism |
Host |
Daucus carota, Carrot |
Organism |
Glomus intraradices |
Country |
Sweden, Europe |
Abstracts |
The influence of external phosphorus (P) on carbon (C)
allocation and metabolism as well as processes related to P
metabolism was studied in monoxenic arbuscular mycorrhiza
cultures of carrot (Daucus carota). Fungal hyphae of Glomus
intraradices proliferated from the solid minimal medium
containing the colonized roots into C-free liquid minimal medium
with different P treatments. The fungus formed around three
times higher biomass in P-free liquid medium than in medium with
2.5 mM inorganic P (high-P). Mycelium in the second experiment
was harvested at an earlier growth stag to study metabolic
processes when the mycelium was actively growing. P treatment
influenced the root P content and [C-13]glucose administered to
the roots 7 d before harvest gave a negative correlation between
root P content and C-13 enrichment in arbuscular mycorrhiza
fungal storage lipids in the extraradical hyphae. Eighteen
percent of the enriched C-13 in extraradical hyphae was
recovered in the fatty acid 16:1omega5 from neutral lipids.
Polyphosphate accumulated in hyphae even in P-free medium. No
influence of P treatment on fungal acid phosphatase activity was
observed, whereas the proportion of alkaline-phosphatase-active
hyphae was highest in high-P medium. We demonstrated the
presence of a motile tubular vacuolar system in G. Intraradices.
This system was rarely seen in hyphae subjected to the highest P
treatment. We concluded that the direct responses of the
extraradical hyphae to the P concentration in the medium are
limited. The effects found in hyphae seemed instead to be
related to increased availability of P to the host root.
|