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

Publication Type:Journal Article
Year of Publication:2010
Authors:ARNOLD, TIM, KIRK, GUYJD, WISSUWA, M, FREI, M, ZHAO, FANG-JIE, MASON, THOMASFD, WEISS, DOMINIKJ
Journal:Plant, Cell & Environment
Volume:33
Issue:3
Date Published:2010
ISBN Number:1365-3040
Keywords:DMA, isotope fractionation, Oryza, Oryza sativa, phytosiderophore, rice, solubilization, stable isotopes, Zinc
Abstract:

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.

URL:http://dx.doi.org/10.1111/j.1365-3040.2009.02085.x
Short Title:Plant, Cell & Environment
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