黄土区金盏菊幼苗根部细胞壁对Pb/Cd复合胁迫响应的FTIR和Raman光谱

植物修复法是新兴的重金属污染土壤修复手段,也是未来极富应用潜力的主流技术之一。植物根部细胞壁作为重金属/土壤/植物相的交界面,天然地成为修复效能调控过程的关键部位和信号通道。植物细胞壁与重金属离子的作用行为具有物理化学和生理生化的双重属性,但以光谱技术为切入点,原位解析植物根部细胞壁对土壤重金属离子的响应关系还不多见。以黄土区修复植物金盏菊幼苗为研究对象,分析Pb/Cd复合胁迫对其根部细胞壁形貌的影响,借助X射线荧光光谱(XRF)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和拉曼光谱(Raman)揭示细胞壁对Pb/Cd胁迫的响应信号。结果发现:Pb/Cd胁迫导致金盏菊根部细胞壁弯曲萎缩,表面分布若干点状深色沉积物颗粒;XRF证实细胞壁Pb/Xd含量增加,但XRD图谱没有发现典型Pb/Xd结晶峰。FTIP图谱中—OH振动峰定位于3 416 cm~(-1)处,表明Pb/Cd离子与—OH间可能存在配位键合;1 701和1 593 cm~(-1)处的特征峰分别移动到1 736和1 618 cm~(-1),说明Pb/Cd胁迫改变了金盏菊根部细胞壁蛋白质结构属性。Raman光谱中2 960 cm~(-1)附近峰强增加,暗示Pb/Cd胁迫影响了细胞壁纤维素分子排列方向。可以认为,细胞壁组分(果胶、蛋白质、纤维素等)和典型官能团(—OH,N—H,C=O等)对于减缓Pb/Cd胁迫引起的金盏菊根部细胞壁毒害效应贡献较大。

Response of FTIR and Raman Spectra on Cell Wall of Calendula Officinalis Seedlings Roots to the Co-Contamination Stress of Lead and Cadmium in Loess

Phytoremediation is a novel method with great potential for site remediation contaminated by heavy metals in future . The cell wall of plant roots is significant to affect the remediation efficiency ,for it is related to the multi‐interface of heavy met‐als ,pedosphere and plant .The relationship between cell wall of plant and heavy metals is complicated ,containing the reaction behavior of physical chemistry ,physiology and biochemistry .At present ,the spectral technologies are not adequately used to in‐vestigate the in‐situ response characteristics between cell wall of plant roots and heavy metals .The Calendulaof ficinalis seed‐lings ,the remediation plant in loess ,were used as experimental sampleswhile the root characteristic variation was revealed on cell wall .The approaches of X‐ray fluorescence (XRF) ,X‐ray diffraction (XRD) ,Fourier transform infrared spectroscopy (FT‐IR) and Raman spectra were applied to analyze the response effect of cell wall to lead/cadmium stress .The results showed :the cell wall appears to be shrinking ,and certain amounts of dark particles appear on cell wall .The contents of lead/cadmium in‐crease greatly as shown from XRF ,while the representative crystals of lead/cadmium are hardly detected .The absorbance peak at 3 416 cm -1 indicates the coordination effect between lead/cadmium and —OH in FTIR ,and the movement of absorbance peaks ,from 1 701 to 1 736 cm -1 and 1 593 to 1 618 cm -1 ,respectively ,indicates the different characteristics of protein in cell wall of Calendulaof ficinalis seedlings roots under lead/cadmium stress .The Raman intensity of absorbance peak at 2 960 cm -1 increases under lead/cadmium stress ,and it proves the changes on arranging directions of cellulose molecules in cell wall sam‐ples .The components (Pectin ,protein ,cellulose ,etc .) and functional groups (—OH ,N— H , CO ,etc .) of cell wall play an important role in the resistance process of cell wall derived from Calendula officinalis seedlings roots to the stress of lead/cadmium in loess .