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Gewählte Publikation:

Jentschke, G; Godbold, DL; Brandes, B.
(2001): Nitrogen limitation in mycorrhizal Norway spruce (Picea abies) seedlings induced mycelial foraging for ammonium: implications for Ca and Mg uptake
PLANT SOIL. 2001; 234(1): 109-117. FullText FullText_BOKU

Abstract:
Although many studies support the importance of the external mycelium for nutrient acquisition of ectomycorrhizal plants, direct evidence for a significant contribution to host nitrogen nutrition is still scarce. We grew nonmycorrhizal seedlings and seedlings mycorrhizal with Paxillus involutus (Batsch) Fr. in a sand culture system with two compartments separated by a 45-mum Nylon mesh. Hyphae, but not roots, can penetrate this net. Nutrient solutions were designed to limit seedling growth by nitrogen. Hyphal density in the hyphal compartment, host N status and shoot growth of mycorrhizal seedlings significantly increased in response to NH4+ addition to the hyphal compartment. Labeling the compartment only accessible to hyphae with (NH4+)-N-15 showed that the increase in N uptake in the mycorrhizal seedlings was a result of hyphal N acquisition from the hyphal compartment. These results indicate that hyphae of P. involutus may actively forage into N-rich patches and improve host N status and growth. In the mycorrhizal seedlings, which received additional NH4+ via their external mycelium, the increase in NH4+ supply less negatively affected Ca and Mg uptake than in nonmycorrhizal seedlings, where the additional NH4+ was directly supplied to the roots. This was most likely due to the close link of NH4+ uptake and H+ extrusion, which, in the nonmycorrhizal seedlings, lead to a strong acidification in the root compartment, and subsequently reduced Ca and Mg uptake, whereas in the mycorrhizal seedlings the site of intensive NH4+ uptake and acidification was in the hyphal and not in the root compartment. Our data support the idea that the ectomycorrhizal mycelium connected to an N-deficient host may actively forage for N. The mycelium may also be important as a biological buffer system ameliorating negative influence of high NH4+ supply on cation uptake.
Autor*innen der BOKU Wien:
Godbold Douglas L.
BOKU Gendermonitor:


Find related publications in this database (Keywords)
calcium
ectomycorrhiza
hyphal transport
magnesium
nitrogen nutrition
Paxillus involutus
Picea abies


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