A dual isotopic approach using radioactive phosphorus and the isotopic composition of oxygen associated to phosphorus to understand plant reaction to a change in P nutrition

Verena Pfahler; Federica Tamburini; Stefano M Bernasconi; Emmanuel Frossard

doi:10.1186/s13007-017-0227-x

A dual isotopic approach using radioactive phosphorus and the isotopic composition of oxygen associated to phosphorus to understand plant reaction to a change in P nutrition

Plant Methods. 2017 Sep 25:13:75. doi: 10.1186/s13007-017-0227-x. eCollection 2017.

Authors

Verena Pfahler^{1

2}, Federica Tamburini¹, Stefano M Bernasconi³, Emmanuel Frossard¹

Affiliations

¹ Department of Environmental Systems Science, ETH Zurich, Eschikon 33, 8315 Lindau, Switzerland.
² Sustainable Agriculture Sciences, Rothamsted Research, Okehampton, Devon EX20 2SB UK.
³ Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8001 Zurich, Switzerland.

Abstract

Background: Changing the phosphorus (P) nutrition leads to changes in plant metabolism. The aim of this study was to investigate how these changes are reflected in the distribution of ³³P and the isotopic composition of oxygen associated to P (δ¹⁸O_P) in different plant parts of soybean (Glycine max cv. Toliman). Two P pools were extracted sequentially with 0.3 M trichloroacetic acid (TCA P) and 10 M nitric acid (HNO₃; residual P).

Results: The δ¹⁸O_P of TCA P in the old leaves of the - P plants (23.8‰) significantly decreased compared to the + P plants (27.4‰). The ³³P data point to an enhanced mobilisation of P from residual P in the old leaves of the - P plants compared to the + P plants.

Conclusions: Omitting P for 10 days lead to a translocation of P from source to sink organs in soybeans. This was accompanied by a significant lowering of the δ¹⁸O_P of TCA P in the source organs due to the enzymatic hydrolysis of organic P. Combining ³³P and δ¹⁸O_P can provide useful insights in plant responses to P omission at an early stage.

Keywords: 33P; Phosphorus; Radioisotopes; Soybeans; Stable isotopes; δ18OP of TCA P.