Mathematical Institute, University of Oxford, Oxford, UK.
Plant Cell Environ. 2011 Dec;34(12):2038-46. doi: 10.1111/j.1365-3040.2011.02401.x. Epub 2011 Aug 23.
Rice (Oryza sativa L.) secretes far smaller amounts of metal-complexing phytosiderophores (PS) than other grasses. But there is increasing evidence that it relies on PS secretion for its zinc (Zn) uptake. After nitrogen, Zn deficiency is the most common nutrient disorder in rice, affecting up to 50% of lowland rice soils globally. We developed a mathematical model of PS secretion from roots and resulting solubilization and uptake of Zn, allowing for root growth, diurnal variation in secretion, decomposition of the PS in the soil, and the transport and interaction of the PS and Zn in the soil. A sensitivity analysis showed that with realistic parameter values for rice in submerged soil, the typically observed rates of PS secretion from rice are sufficient and necessary to explain observed rates of Zn uptake. There is little effect of diurnal variation in secretion on cumulative Zn uptake, irrespective of other model parameter values, indicating that the observed diurnal variation is not causally related to Zn uptake efficiency. Rooting density has a large effect on uptake per unit PS secretion as a result of overlap of the zones of influence of neighbouring roots. The effects of other complications in the rice rhizosphere are discussed.
水稻（Oryza sativa L.）分泌的金属配位型植物铁载体（PS）比其他禾本科植物少得多。但越来越多的证据表明，水稻依赖 PS 的分泌来吸收锌（Zn）。除氮外，Zn 缺乏是水稻中最常见的营养失调症，全球多达 50%的低地稻田受到影响。我们开发了一个从根部分泌 PS 并导致 Zn 溶解和吸收的数学模型，该模型考虑了根部生长、分泌的昼夜变化、土壤中 PS 的分解以及 PS 和 Zn 在土壤中的运输和相互作用。敏感性分析表明，对于淹水土壤中的水稻，具有现实的参数值，通常观察到的 PS 分泌速率足以且必需解释观察到的 Zn 吸收速率。无论其他模型参数值如何，分泌的昼夜变化对累积 Zn 吸收的影响都很小，这表明观察到的昼夜变化与 Zn 吸收效率没有因果关系。由于邻近根系的影响区域重叠，根系密度对单位 PS 分泌的吸收量有很大影响。还讨论了水稻根际的其他复杂性的影响。
