Institute of Agricultural Sciences, ETH Zurich, Eschikon 33, 8315, Lindau, Switzerland.
Geological Institute, ETH Zurich, Sonneggstrasse 5, 8092, Zurich, Switzerland.
New Phytol. 2013 Jan;197(1):186-193. doi: 10.1111/j.1469-8137.2012.04379.x. Epub 2012 Oct 29.
The objective of this study was to investigate the isotopic composition of oxygen bound to phosphate (δ(18)O-PO(4)) in different phosphorus (P) pools in plant leaves. As a model plant we used soybean (Glycine max cv Toliman) grown in the presence of ample P in hydroponic cultures. The leaf blades were extracted with 0.3 M trichloroacetic acid (TCA) and with 10 M nitric acid. These extractions allowed measurement of the TCA-soluble reactive P (TCA P) that is rapidly cycled within the cell and the total leaf P. The difference between total leaf P and TCA P yielded the structural P which includes organic P compounds not extractable by TCA. P uptake and its translocation and transformation within the soybean plants lead to an (18)O enrichment of TCA P (δ(18)O-PO(4) between 16.9 and 27.5‰) and structural P (δ(18)O-PO(4) between 42.6 and 68.0 ‰) compared with 12.4‰ in the phosphate in the nutrient solution. δ(18)O values of phosphate extracted from soybean leaves grown under optimal conditions are greater than the δ(18)O-PO(4) values of the provided P source. Furthermore, the δ(18)O-PO(4) of TCA P seems to be controlled by the δ(18)O of leaf water and the activity of inorganic pyrophosphatase or other pyrophosphatases.
本研究旨在探究植物叶片中不同磷库中与磷酸根结合的氧同位素组成（δ(18)O-PO(4)）。我们选择大豆（Glycine max cv Toliman）作为模式植物，在水培条件下充足供应磷进行培养。采用 0.3 M 三氯乙酸（TCA）和 10 M 硝酸对叶片进行提取，分别测定 TCA 可溶反应性磷（TCA P）和总叶片磷。总叶片磷与 TCA P 的差值即为结构磷，包括 TCA 不可提取的有机磷化合物。大豆植株对磷的吸收、转运和转化导致 TCA P（δ(18)O-PO(4)值在 16.9‰至 27.5‰之间）和结构磷（δ(18)O-PO(4)值在 42.6‰至 68.0‰之间）相对于营养液中磷酸盐的 12.4‰发生富集。在最佳条件下生长的大豆叶片中提取的磷酸盐的 δ(18)O 值大于所提供磷源的 δ(18)O-PO(4)值。此外，TCA P 的 δ(18)O-PO(4)似乎受叶片水的 δ(18)O 和无机焦磷酸酶或其他焦磷酸酶活性的控制。
