期刊
PLANTA
卷 237, 期 4, 页码 919-931出版社
SPRINGER
DOI: 10.1007/s00425-012-1807-7
关键词
Efflux; Fertilizer; Influx; Ion uptake; Poplar; Proton
资金
- National Key Basic Research Program of China (973 Program) [2012CB416902]
- National Natural Science Foundation of China [31070539, 31100481, 31270647]
- Special Fund for Forest Science and Technology Research in the Public Interest [201204210]
- Program for New Century Excellent Talents in University from the Ministry of Education of China [NCET-08-0468]
- Fok Ying Tung Education Foundation [121026]
- Specialized Research Fund for the Doctoral Program of Higher Education of China [20090204110027]
- Fundamental Research Funds for the Central Universities of China [QN2009063]
Poplar plants are cultivated as woody crops, which are often fertilized by addition of ammonium (NH4 (+)) and/or nitrate (NO3 (-)) to improve yields. However, little is known about net NH4 (+)/NO3 (-) fluxes and their relation with H+ fluxes in poplar roots. In this study, net NH4 (+)/NO3 (-) fluxes in association with H+ fluxes were measured non-invasively using scanning ion-selective electrode technique in fine roots of Populus popularis. Spatial variability of NH4 (+) and NO3 (-) fluxes was found along root tips of P. popularis. The maximal net uptake of NH4 (+) and NO3 (-) occurred, respectively, at 10 and 15 mm from poplar root tips. Net NH4 (+) uptake was induced by ca. 48 % with provision of NO3 (-) together, but net NO3 (-) uptake was inhibited by ca. 39 % with the presence of NH4 (+) in poplar roots. Furthermore, inactivation of plasma membrane (PM) H+-ATPases by orthovanadate markedly inhibited net NH4 (+)/NO3 (-) uptake and even led to net NH4 (+) release with NO3 (-) co-provision. Linear correlations were observed between net NH4 (+)/NO3 (-) and H+ fluxes in poplar roots except that no correlation was found between net NH4 (+) and H+ fluxes in roots exposed to NH4Cl and 0 mM vanadate. These results indicate that root tips play a key role in NH4 (+)/NO3 (-) uptake and that net NH4 (+)/NO3 (-) fluxes and the interaction of net fluxes of both ions are tightly associated with H+ fluxes in poplar roots.
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