Aix Marseille Univ, CNRS, IRD, INRAE, Coll France, CEREGE UMR 7330, Aix en Provence, France.
Aix Marseille Univ, CNRS, IRD, INRAE, Coll France, CEREGE UMR 7330, Aix en Provence, France.
Environ Pollut. 2021 Jun 15;279:116897. doi: 10.1016/j.envpol.2021.116897. Epub 2021 Mar 13.
It has been proposed that non-protein thiols and organic acids play a major role in cadmium phytoavailability and distribution in plants. In the Cd-hyperaccumulator Solanum nigrum and non-accumulator Solanum melongena, the role of these organic ligands in the accumulation and detoxification mechanisms of Cd are debated. In this study, we used X-ray absorption spectroscopy to investigate Cd speciation in these plants (roots, stem, leaves) and in the soils used for their culture to unravel the plants responses to Cd exposure. The results show that Cd in the 100 mg kg Cd-doped clayey loam soil is sorbed onto iron oxyhydroxides. In both S. nigrum and S. melongena, Cd in roots and fresh leaves is mainly bound to thiol ligands, with a small contribution of inorganic S ligands in S. nigrum leaves. We interpret the Cd binding to sulfur ligands as detoxification mechanisms, possibly involving the sequestration of Cd complexed with glutathione or phytochelatins in the plant vacuoles. In the stems, results show an increase binding of Cd to -O ligands (>50% for S. nigrum). We suggest that Cd is partly complexed by organic acids for transportation in the sap.
有人提出，非蛋白巯基和有机酸在植物中镉的生物有效性和分布中起着重要作用。在镉超积累植物龙葵和非积累植物茄子中，这些有机配体在镉的积累和解毒机制中的作用存在争议。在这项研究中，我们使用 X 射线吸收光谱法研究了这些植物（根、茎、叶）和用于培养它们的土壤中 Cd 的形态，以揭示植物对 Cd 暴露的反应。结果表明，在 100mgkg Cd 掺杂的粘壤土中，Cd 被吸附到铁氢氧化物上。在龙葵和茄子中，根和新鲜叶片中的 Cd 主要与巯基配体结合，而在龙葵叶片中无机 S 配体的贡献较小。我们将 Cd 与硫配体的结合解释为解毒机制，可能涉及将与谷胱甘肽或植物螯合肽结合的 Cd 螯合到植物液泡中。在茎中，结果表明 Cd 与-O 配体的结合增加（对于龙葵，超过 50%）。我们认为 Cd 部分与有机酸结合，以便在树液中运输。
