Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, St Lucia, Qld, 4072, Australia.
Laboratoire Sols et Environnement, UMR 1120, Université de Lorraine-INRA, 54518, Vandoeuvre-lès-Nancy, France.
New Phytol. 2018 Apr;218(2):432-452. doi: 10.1111/nph.14810. Epub 2017 Oct 10.
Contents Summary 432 I. Introduction 433 II. Preparation of plant samples for X-ray micro-analysis 433 III. X-ray elemental mapping techniques 438 IV. X-ray data analysis 442 V. Case studies 443 VI. Conclusions 446 Acknowledgements 449 Author contributions 449 References 449 SUMMARY: Hyperaccumulators are attractive models for studying metal(loid) homeostasis, and probing the spatial distribution and coordination chemistry of metal(loid)s in their tissues is important for advancing our understanding of their ecophysiology. X-ray elemental mapping techniques are unique in providing in situ information, and with appropriate sample preparation offer results true to biological conditions of the living plant. The common platform of these techniques is a reliance on characteristic X-rays of elements present in a sample, excited either by electrons (scanning/transmission electron microscopy), protons (proton-induced X-ray emission) or X-rays (X-ray fluorescence microscopy). Elucidating the cellular and tissue-level distribution of metal(loid)s is inherently challenging and accurate X-ray analysis places strict demands on sample collection, preparation and analytical conditions, to avoid elemental redistribution, chemical modification or ultrastructural alterations. We compare the merits and limitations of the individual techniques, and focus on the optimal field of applications for inferring ecophysiological processes in hyperaccumulator plants. X-ray elemental mapping techniques can play a key role in answering questions at every level of metal(loid) homeostasis in plants, from the rhizosphere interface, to uptake pathways in the roots and shoots. Further improvements in technological capabilities offer exciting perspectives for the study of hyperaccumulator plants into the future.
内容摘要 432 I. 引言 433 II. 用于 X 射线微分析的植物样品制备 433 III. X 射线元素图谱技术 438 IV. X 射线数据分析 442 V. 案例研究 443 VI. 结论 446 致谢 449 作者贡献 449 参考文献 449 摘要：超积累植物是研究金属（类）内稳态的理想模型，探测金属（类）在其组织中的空间分布和配位化学对于深入了解其生理生态具有重要意义。X 射线元素图谱技术在提供原位信息方面具有独特的优势，并且通过适当的样品制备，可以提供真实反映活体植物生物学条件的结果。这些技术的共同平台是依赖于样品中存在元素的特征 X 射线，这些 X 射线可以通过电子（扫描/透射电子显微镜）、质子（质子诱导 X 射线发射）或 X 射线（X 射线荧光显微镜）激发。阐明金属（类）在细胞和组织水平上的分布具有内在的挑战性，准确的 X 射线分析对样品收集、制备和分析条件提出了严格的要求，以避免元素再分配、化学修饰或超微结构改变。我们比较了各技术的优缺点，并重点介绍了推断超积累植物生理生态过程的最佳应用领域。X 射线元素图谱技术可以在植物金属（类）内稳态的各个层面上发挥关键作用，从根际界面到根和茎中的吸收途径。技术能力的进一步提高为未来研究超积累植物提供了令人兴奋的前景。
