Visualizing the distribution of various inorganic metals in brown rice by radiotracer experiments

Abstract

The distribution of inorganic elements in brown rice has been vigorously investigated for many years using the most advanced instruments of each era. The present study was a challenge to gain new insights into the distribution of various inorganic elements in brown rice by autoradiography using radioisotopes: 22Na, 45Ca, 54Mn, 55Fe, 60Co, 63Ni, 65 Zn, 90Sr, 203 Hg, and 210 Pb. Autoradiography of tissue sections using the Imaging Plate (IP) fully exploited its advantage of high-throughput imaging, enabling three-dimensional reconstruction that encompassed the entire brown rice grain. Consequently, characteristic distribution patterns of individual elements in the peripheral layer, endosperm, and embryo were identified following radiotracer supplementation to the culture solution. For instance, 63Ni was uniformly distributed within the endosperm during the early stages of development but progressively accumulated in the outer layers and embryo as growth advanced; such a pattern was not observed for 54Mn or 55Fe. To minimize the cost of the experiment, a direct injection method into the node was developed. This approach successfully visualized 203 Hg, demonstrating that its entry into the embryonic tissue is severely restricted irrespective of the developmental stage of the rice grain.

Plant phenotyping relevance

褐色米粒を対象に、オートラジオグラフィーとイメージングプレートで元素分布を高スループットに可視化し、三次元再構成する測定手法を中心に扱っているため、植物器官の状態を抽出するフェノタイピング手法として含める。

Code and data availability

The supplied article blocks describe radiotracer autoradiography of brown rice and PHITS simulations, but contain no data availability statement, deposited phenotype/imaging datasets, author analysis code, or trained models. The only URL present is the Creative Commons license link, which is not a paper-specific asset.

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