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Nitrogen delivery to maize via mycorrhizal hyphae depends on the form of N supplied
Author(s) -
TANAKA YOKO,
YANO KATSUYA
Publication year - 2005
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2005.01360.x
Subject(s) - hypha , ammonium , fungus , nutrient , mycorrhiza , nitrate , botany , nitrogen , phosphorus , shoot , ammonium nitrate , biology , chemistry , symbiosis , bacteria , ecology , genetics , organic chemistry
Arbuscular mycorrhizal fungi can enhance nutrient acquisition by a plant via their extraradical hyphae. This is particularly true for phosphorus, but the case for nitrogen (N) has been less clear. In our growth systems there was a small air‐gap between root and hyphal compartments, which eliminated diffusion of nutrients between compartments. Moreover, our methods allowed us to distinguish between nitrate and ammonium. We found that N transfer to Zea maize L. depends on the sources fed to the hyphae of Glomus aggregatum Schenck & Smith. In experiment 1, despite the fact that plant demand for N was already met, plants received 10 times as much 15 N from ammonium than from nitrate. In experiment 2, 74% of shoot‐N was derived from the slow‐release urea added to the hyphal compartment while only 2.9% was derived from the nitrate‐N. Intraradical hyphae isolated from roots contained a considerable amount of 15 N in the cell wall even when 15 N‐nitrate was the source. We conclude that the mycorrhizal fungus can rapidly deliver ammonium‐N to the plants, and that while the fungus can absorb nitrate, it apparently lacks the capacity to transfer it to the plant.