Evidence for the mechanisms of zinc uptake by rice using isotope fractionation

Summary, in English

In an earlier study, we found that rice (Oryza sativa) grown in nutrient solution well-supplied with Zn preferentially took up light ⁶⁴Zn over ⁶⁶Zn, probably as a result of kinetic fractionation in membrane transport processes. Here, we measure isotope fractionation by rice in a submerged Zn-deficient soil with and without Zn fertilizer. We grew the same genotype as in the nutrient solution study plus low-Zn tolerant and intolerant lines from a recombinant inbred population. In contrast to the nutrient solution, in soil with Zn fertilizer we found little or heavy isotopic enrichment in the plants relative to plant-available Zn in the soil, and in soil without Zn fertilizer we found consistently heavy enrichment, particularly in the low-Zn tolerant line. These observations are only explicable by complexation of Zn by a complexing agent released from the roots and uptake of the complexed Zn by specific root transporters. We show with a mathematical model that, for realistic rates of secretion of the phytosiderophore deoxymugineic acid (DMA) by rice, and realistic parameters for the Zn-solubilizing effect of DMA in soil, solubilization and uptake by this mechanism is necessary and sufficient to account for the measured Zn uptake and the differences between genotypes.

• Author: Tim Arnold; Guy J.D. Kirk; Matthias Wissuwa; Michael Frei; Fang Jie Zhao; Thomas F.D. Mason; Dominik J. Weiss
• Publishing year: 2010-03
• Language: English
• Pages: 370-381
• Publication/Series: Plant, Cell and Environment
• Volume: 33
• Issue: 3
• Links: http://dx.doi.org/10.1111/j.1365-3040.2009.02085.x
• Document type: Journal article
• Publisher: John Wiley & Sons Inc.
• Keywords: DMA; Isotope fractionation; Phytosiderophore; Rice; Solubilization; Stable isotopes; Zinc
• Status: Published
• ISBN/ISSN/Other: ISSN: 0140-7791