Calcium oxalate (CaOx) crystals in plants may serve as a sink for the absorption of excess calcium, and they could play an important role in heavy metal detoxification. In this study, the effect of heavy metals and different calcium concentrations on the growth of calcium oxalate crystals in leaves of Phaseolus vulgaris was investigated. Different analytical techniques were used to determine the influence of exogenous lead and zinc on CaOx deposition and to detect a presence of these metals in CaOx crystals. We found a positive correlation between the calcium concentration in the nutrient medium and the production of calcium oxalate crystals in leaves of hydroponically grown plants. On the other hand, addition of the heavy metals to the nutrient medium decreased the number of crystals. Energy dispersive X-ray spectrometry did not detect the inclusion of heavy metals inside the CaOx crystals. Our investigation suggests that CaOx crystals do not play a major role in heavy metal detoxification in P. vulgaris but do play an important role in bulk calcium regulation.

中文翻译：

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重金属胁迫减少了菜豆叶片中草酸钙晶体的沉积

植物中的草酸钙 (CaOx) 晶体可以作为吸收过量钙的汇，它们在重金属解毒中起重要作用。本研究考察了重金属和不同钙浓度对菜豆叶片草酸钙晶体生长的影响。使用不同的分析技术来确定外源性铅和锌对 CaOx 沉积的影响，并检测 CaOx 晶体中这些金属的存在。我们发现营养培养基中的钙浓度与水培植物叶片中草酸钙晶体的产生呈正相关。另一方面，向营养培养基中添加重金属会减少晶体的数量。能量色散 X 射线光谱法未检测到 CaOx 晶体内包含重金属。我们的研究表明，CaOx 晶体在 P. vulgaris 的重金属解毒中不起主要作用，但在大量钙调节中起重要作用。