The Guangxi Key Laboratory of Environmental Engineering, Protection and Assessment, Guilin University of Technology, Guilin, Guangxi, China.
Int J Phytoremediation. 2012 Dec;14(10):966-77. doi: 10.1080/15226514.2011.636406.
This study examined the relationship between oxalic acid and Cr tolerance in an accumulating plant Leersia hexandra Swartz. The plants grown in hydroponics were exposed to Cr at 0, 5, 30, and 60 mg/L (without oxalate), and 0, 40, and 80 mg/L concentrations of Cr (with 70 mg/L oxalate or without oxalate). The results showed that more than 50% of Cr in shoots was found in HCl-extracted fraction (chromium oxalate) when the plants were exposed to Cr. Cr supply significantly increased oxalate concentration in shoots of L. hexandra (p < 0.05), but did not increase oxalate concentration in roots. Under 80 mg/L Cr stress, electrolyte leakages from roots and shoots with oxalate treatment were both significantly lower than those without oxalate treatment (p < 0.05), indicating exogenous oxalate supply alleviated Cr-induced membrane damage. Oxalate added to growth solution ameliorated reduction of biomass and inhibition of root growth induced by Cr, which demonstrated that application of oxalate helped L. hexandra tolerate Cr stress. However, oxalate supply did not affect the Cr concentrations both in roots and shoots of L. hexandra. These results suggest that oxalic acid may act as an important chelator and takes part in detoxifying chromium in internal process of L. hexandra.
本研究探讨了草酸与耐铬积累植物李氏禾（Leersia hexandra Swartz）之间的关系。在水培条件下，将植物暴露于 0、5、30 和 60mg/L（无草酸）以及 0、40 和 80mg/L（含 70mg/L 草酸或无草酸）的 Cr 中。结果表明，当植物暴露于 Cr 时，超过 50%的 Cr 存在于茎部的 HCl 提取部分（草酸铬）中。Cr 的供应显著增加了李氏禾茎部的草酸浓度（p<0.05），但未增加根部的草酸浓度。在 80mg/L Cr 胁迫下，添加草酸的根和茎的电解质渗漏均显著低于未添加草酸的处理（p<0.05），表明外源性草酸的供应缓解了 Cr 诱导的膜损伤。添加到生长溶液中的草酸改善了 Cr 引起的生物量减少和根生长抑制，表明草酸的应用有助于李氏禾耐受 Cr 胁迫。然而，草酸的供应并不影响李氏禾根和茎部的 Cr 浓度。这些结果表明，草酸可能作为一种重要的螯合剂，参与李氏禾内部过程中 Cr 的解毒。
