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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

Author:
Pfahler, Verena, Tamburini, Federica, Bernasconi, StefanoM., Frossard, Emmanuel
Source:
Plant methods 2017 v.13 no.1 pp. 75
ISSN:
1746-4811
Subject:
Glycine max, enzymatic hydrolysis, leaves, metabolism, nitric acid, nutrition, oxygen, phosphorus, plant response, soybeans, trichloroacetic acid
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 (δ¹⁸OP) 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 δ¹⁸OP 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 δ¹⁸OP of TCA P in the source organs due to the enzymatic hydrolysis of organic P. Combining ³³P and δ¹⁸OP can provide useful insights in plant responses to P omission at an early stage.