SCRI, Invergowrie, Dundee, UK.
Ann Bot. 2011 Apr;107(4):681-91. doi: 10.1093/aob/mcr009. Epub 2011 Feb 2.
The three-dimensional distributions of mineral elements in potato tubers provide insight into their mechanisms of transport and deposition. Many of these minerals are essential to a healthy human diet, and characterizing their distribution within the potato tuber will guide the effective utilization of this staple foodstuff.
The variation in mineral composition within the tuber was determined in three dimensions, after determining the orientation of the harvested tuber in the soil. The freeze-dried tuber samples were analysed for minerals using inductively coupled plasma-mass spectrometry (ICP-MS). Minerals measured included those of nutritional significance to the plant and to human consumers, such as iron, zinc, copper, calcium, magnesium, manganese, phosphorus, potassium and sulphur.
The concentrations of most minerals were higher in the skin than in the flesh of tubers. The potato skin contained about 17 % of total tuber zinc, 34 % of calcium and 55 % of iron. On a fresh weight basis, most minerals were higher in tuber flesh at the stem end than the bud end of the tuber. Potassium, however, displayed a gradient in the opposite direction. The concentrations of phosphorus, copper and calcium decreased from the periphery towards the centre of the tuber.
The distribution of minerals varies greatly within the potato tuber. Low concentrations of some minerals relative to those in leaves may be due to their low mobility in phloem, whereas high concentrations in the skin may reflect direct uptake from the soil across the periderm. In tuber flesh, different minerals show distinct patterns of distribution in the tuber, several being consistent with phloem unloading in the tuber and limited onward movement. These findings have implications both for understanding directed transport of minerals in plants to stem-derived storage organs and for the dietary implications of different food preparation methods for potato tubers.
马铃薯块茎中矿物质元素的三维分布情况可以帮助我们深入了解其运输和沉积机制。许多矿物质元素对人类健康饮食至关重要，因此，对这些矿物质元素在马铃薯块茎中的分布情况进行描述，将有助于指导人们有效利用这种主食。
在确定收获的马铃薯块茎在土壤中的方位后，对其三维方向上的块茎内矿物质组成进行了分析。采用电感耦合等离子体质谱法（ICP-MS）对冷冻干燥后的块茎样本进行矿物质分析。所测量的矿物质包括对植物和人类消费者具有重要意义的营养物质，如铁、锌、铜、钙、镁、锰、磷、钾和硫。
大多数矿物质在马铃薯块茎的表皮中的浓度要高于肉质部分。马铃薯皮中大约含有 17%的总锌、34%的钙和 55%的铁。以新鲜重量为基准，大多数矿物质在块茎茎端的肉质部分的含量要高于芽眼端。钾则相反，呈相反方向的梯度分布。磷、铜和钙的浓度从块茎的外周向中心逐渐降低。
矿物质在马铃薯块茎内的分布差异很大。与叶片中的矿物质相比，某些矿物质的浓度相对较低，这可能是由于它们在韧皮部中的移动性较低；而在表皮中浓度较高，则可能反映了它们通过周皮直接从土壤中吸收。在块茎肉质部分，不同的矿物质呈现出不同的分布模式，其中一些与韧皮部向块茎的卸载有关，而其他一些则限制了进一步的移动。这些发现对于理解植物中矿物质向茎源性贮藏器官的定向运输以及不同的马铃薯块茎食用方法对饮食的影响都具有重要意义。
