用激光剥蚀电感耦合等离子体质谱研究小麦籽粒元素的共分布

增加粮食可食用部分微量营养元素的浓度, 需要更好地了解其在植株, 特别是籽粒内的运输和分布规律。激光剥蚀电感耦合等离子体质谱(laser ablation inductively coupled plasma mass spectrometry, LA-ICP-MS)是一种测定植物组织中元素空间分布的新技术。采用该技术对成熟小麦籽粒中锰(Mn)、铜(Cu)、锌(Zn)和磷(P)的空间分布及其关联程度定量研究。结果表明, 所测元素在籽粒不同部位的浓度分布差异很大。Cu、Zn和P浓度均以糊粉层最高, 胚乳最低, 胚居中, 浓度最大差异分别达15、42和33倍; Mn浓度则以胚最高, 胚乳最低, 糊粉层居中, 浓度最大差异达9倍。籽粒同一部位不同位置的元素浓度亦不相同, 外周胚乳(靠近糊粉层)的元素浓度大于内侧胚乳部位对应元素的浓度, 胚最外侧盾片部位的元素浓度大于胚中间位置的元素浓度, 且各元素趋势一致。比较分析发现, 麦粒不同部位元素的浓度变化存在明显的同步性, 籽粒中P浓度高的部位金属元素(Mn、Cu和Zn)浓度也高。这说明不同元素在向籽粒不同部位运输和积累过程中可能存在密切关联性。

Element Colocalization in Wheat Seed Revealed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)

For enhancement of micronutrient concentrations in edible parts of food crops, element uptake and partition in plants, especially in seeds, should be better understanded. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a recently developed technology for examining mineral elements distribution in plant tissues. By using this technique, we quanti-tatively measured distributions of manganese (Mn), copper (Cu), zinc (Zn), and phosphorus (P) in different parts of wheat seeds. The concentrations of Cu, Zn, and P were the highest in aleurone layer and the lowest in endosperm with the difference of 15, 42, and 33 folds, respectively. The Mn concentration was the highest in embryo, which was 9-fold higher than the lowest concentra-tion in endosperm. The concentration gradients of measured elements were also found in same parts of wheat grain. The concen-trations of P, Mn, Cu, and Zn in endosperm close to aleurone layer were higher than those in the middle of wheat seed. Similarly, the element concentrations in scutellum were higher than those in embryo axis. The four elements had similar distribution pattern in wheat seed with a clear synchronization. This phenomenon suggested the colocalization of these elements in wheat seeds. Therefore, the translocations and accumulations of P, Mn, Cu, and Zn in wheat seeds might be closely related to each other, and the finding is useful for wheat biofortification programs in the future.