Nitrogen delivery to maize via mycorrhizal hyphae depends on the form of N supplied
Nitrogen delivery to maize via mycorrhizal hyphae depends on the form of N supplied
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DOI：
10.1111/j.1365-3040.2005.01360.x
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发表时间：
2005-10-01
影响因子：
7.3
通讯作者：
Yano, K
中科院分区：
文献类型：
--
作者：
Tanaka, Y;Yano, K
丛枝菌根真菌可以通过其根外菌丝增强植物的营养获取。对磷来说尤其如此，但对氮(N)的情况就不那么清楚了。在我们的生长系统中，根室和菌丝室之间有一个小的气隙，这就消除了养分在室之间的扩散。此外，我们的方法使我们能够区分硝酸盐和铵。我们发现氮向玉米的转移取决于施给Glomus aggregatum Schenck & Smith菌丝的来源。在试验1中，尽管植物对氮的需求已经得到满足，但植物从铵中获得的N-15是从硝酸盐中获得的10倍。在试验2中，74%的氮素来源于菌丝室中添加的缓释尿素，只有2.9%来源于硝酸盐氮素。从根中分离出的根内菌丝即使以N-15-硝酸盐为来源，细胞壁中也含有相当数量的N-15。结果表明，菌根真菌可以快速地向植株输送氨氮，而菌根真菌可以吸收硝态氮，但显然缺乏向植株输送硝态氮的能力。
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 N-15 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 N-15 in the cell wall even when N-15-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.