Evidence for the mechanisms of zinc uptake by rice using isotope fractionation
Evidence for the mechanisms of zinc uptake by rice using isotope fractionation
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DOI：
10.1111/j.1365-3040.2009.02085.x
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发表时间：
2010-03-01
影响因子：
7.3
通讯作者：
Weiss, Dominik J.
中科院分区：
文献类型：
--
作者：
Arnold, Tim;Kirk, Guy J. D.;Weiss, Dominik J.
在一项早期研究中，我们发现在锌供应充足的营养液中生长的水稻（Oryza sativa）优先吸收轻质 64Zn，而不是 66Zn，这可能是膜运输过程中动力学分馏的结果。在这里，我们测量了在有或没有锌肥料的淹没缺锌土壤中水稻的同位素分馏。我们培养了与营养液研究中相同的基因型，加上来自重组近交群体的低锌耐受和不耐受品系。与营养液相反，在施有锌肥的土壤中，我们发现相对于土壤中植物可利用的锌，植物体内的同位素富集很少或较重，而在没有施锌肥的土壤中，我们发现植物体内的同位素富集持续较重，特别是在低锌耐受品系中。这些观察结果只能通过从根部释放的络合剂络合 Zn 以及特定根转运蛋白吸收络合的 Zn 来解释。我们用数学模型证明，对于水稻植物铁载体脱氧麦根酸（DMA）的实际分泌率，以及土壤中 DMA 增溶锌效果的实际参数，这种机制的增溶和吸收是必要且充分的，以解释测量的锌吸收和基因型之间的差异。
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.