Germanium-68 as an Adequate Tracer for Silicon Transport in Plants.: Characterization of Silicon Uptake in Different Crop Species
Germanium-68 as an Adequate Tracer for Silicon Transport in Plants.: Characterization of Silicon Uptake in Different Crop Species
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DOI：
10.1104/pp.106.090845
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发表时间：
2007-01-01
期刊：
影响因子：
7.4
通讯作者：
Romheld, Volker
中科院分区：
文献类型：
--
作者：
Nikolic, Miroslav;Nikolic, Nina;Romheld, Volker
生物学中硅 (Si) 吸收研究的一个基本问题是缺乏合适的放射性同位素。放射性锗 68 (Ge-68) 以前已被用作生物材料中的硅示踪剂，但其在高等植物中硅转运研究的适用性尚未经过测试。在本研究中，我们研究了四种对 Si 的吸收能力差异很大的作物品种对 Ge-68 示踪的 Si 吸收，包括水稻 (Oryza sativa)、大麦 (Hordeum vulgare)、黄瓜 (Cucumis sativus) 和番茄 (Lycopersicon esculentum)。所有四种植物物种的植物组织中的 Ge-68:Si 摩尔比的维持与在各种 Si 浓度范围内的营养液中提供的摩尔比相似，这表明 Ge-68 和 Si 之间不存在区别。此外，使用 Ge-68 示踪剂，在水稻、大麦和黄瓜中发现了典型的米氏硅吸收动力学。与水稻相比，大麦和黄瓜中硅从根到茎易位的相对比例较低，尤其是番茄（仅30%）。水稻、大麦和黄瓜（硅积累体）中硅的吸收和转运受到2,4-二硝基苯酚和HgCl2的强烈抑制，但在番茄中，作为一种排除硅的物种，两种抑制剂产生相反的效果。总之，我们的结果表明使用 Ge-68 示踪剂方法作为未来研究植物中硅传输的适当选择。我们的研究结果还表明，硅排除者皮层中硅从共质体到质外体的限制是一个代谢活跃的过程。
A basic problem in silicon (Si) uptake studies in biology is the lack of an appropriate radioactive isotope. Radioactive germanium-68 (Ge-68) has been used previously as a Si tracer in biological materials, but its suitability for the study of Si transport in higher plants is still untested. In this study, we investigated Ge-68-traced Si uptake by four crop species differing widely in uptake capacity for Si, including rice (Oryza sativa), barley (Hordeum vulgare), cucumber (Cucumis sativus), and tomato (Lycopersicon esculentum). Maintenance of a Ge-68:Si molar ratio that was similar in the plant tissues of all four plant species to that supplied in the nutrient solution over a wide range of Si concentrations demonstrated the absence of discrimination between Ge-68 and Si. Further, using the Ge-68 tracer, a typical Michaelis-Menten uptake kinetics for Si was found in rice, barley, and cucumber. Compared to rice, the relative proportion of root-to-shoot translocated Si was lower in barley and cucumber and especially in tomato (only 30%). Uptake and translocation of Si in rice, barley, and cucumber (Si accumulators) were strongly inhibited by 2,4-dinitrophenol and HgCl2, but in tomato, as a Si-excluding species, both inhibitors produced the opposite effect. In conclusion, our results suggest the use of the Ge-68 tracer method as an appropriate choice for future studies of Si transport in plants. Our findings also indicate that the restriction of Si from symplast to apoplast in the cortex of Si excluders is a metabolically active process.