Recent advances in 2d imaging of element distribution in plants by focused beam techniques

Abstract

As sessile organisms, plants must constantly adapt to environmental changes. Plant performance is related to availability of light, water, and mineral nutrients, which is especially important in agricultural systems, where minerals are removed from the fields at harvest. Mineral nutrients are also essential for the normal functioning of animal and human body. Since plants are world’s primary producers representing the basis for animal and human diet, it is of extreme importance that they contain sufficient amounts of mineral nutrients and low amounts of antinutrients and noxious elements. To maintain homeostasis with optimal cell functioning and integrity, proper allocation of elements at organ, tissue, cellular, and subcellular level is essential. Studies of element localization are therefore crucial to uncover the mechanisms of element transport and accumulation, toxicity, and tolerance. In the last two decades, a remarkable progress has been made in the development and application of different 2D imaging techniques in complex biological systems, especially with regard to improved lateral resolution and sensitivity as well as sample preparation. In this chapter, the latest development and applications of focused beam techniques like microparticle-induced X-ray emission (µ-PIXE), micro-X-ray fluorescence spectrometry (µ-XRF), and laser ablation inductively coupled plasma-mass spectrometry (LA-ICPMS) in imaging the distributions of major and trace elements in plants are presented. These techniques are unique in providing in situ information and, with appropriate sample preparation, provide results true to biological condition of the living plants. For example the methods for sampling and sample preparation can in conjunction with measurement conditions compromise the element distribution: critical consideration is therefore required when reporting “in vivo” elemental distribution and concentration.