金盏菊原生质体对土壤铅/镉响应机制的FTIR,2D-IR和XPS证据

FTIR,2D-IR and XPS Analyses on the Mechanism of Protoplast Derived From Calendula Officinalis in Response to Lead and Cadmium in Soil

土壤修复是“十四五”期间国家重点支持的环保领域,是实现社会可持续发展的重要保障。与其他方法相比,植物修复技术整体优势突出,对于土壤重金属的去除净化更为有效。原生质体是植物细胞代谢活动的重要场所,相对于细胞壁而言,原生质体对重金属胁迫的生理响应同样强烈。现阶段,同类植物修复机制研究多从分子生物学层面切入;本研究则从谱学角度展开,初步探究植物原生质体对土壤重金属的反馈信号。以代表性的菊科植物金盏菊为研究对象,通过Pb/Cd胁迫盆栽实验获取金盏菊样本,差速冷冻离心法得到金盏菊原生质体。引入Tessier连续提取-原子吸收光谱法(AAS)揭示胁迫强度与Pb/Cd赋存形态的内在关联,结合X射线衍射光谱(XRD)、傅里叶变换红外光谱(FTIR)、二维相关红外光谱(2D-IR)和X射线光电子能谱(XPS)识别金盏菊原生质体对Pb/Cd响应的谱学表现。结果表明:金盏菊原生质体可交换态Pb/Cd比例不高,胁迫强度对不同形态Cd含量影响很小。XRD图谱最强信号出现在31.7°(NaCl晶体),同时检测出Pb盐[Pb_(5)(PO_(4))_(3)Cl]和Cd盐(CdS)特征峰。FTIR图谱的3510 cm^(-1)附近强吸收带源于—OH伸缩振动,胁迫过程导致峰形杂乱、峰位偏移;2D-IR结果说明Pb/Cd优先与金盏菊原生质体—OH和C O结合。从XPS图谱可以看出,反应前后原生质体C,O元素结合能有异。C(1 s)结合能略有增加,说明C原子参与了配位反应;O(1 s)峰位有所偏转,暗示含O基团对Pb/Cd的结合包含多种途径。新出现的Pb(4 f)峰源于π电子-Pb的交互作用;胁迫浓度增加导致Cd(3 d)结合能升高,表明Cd具有明显失电子倾向。相关结果可以与前期获得的Pb/Cd/金盏菊细胞壁结合特性互为补充,对于完善同领域的深度和广度、构建植物修复理论和技术体系意义重大。

Soil remediation is the key issue supported by t he national government in the 14^(th) Five-Year Plan for Economic and Social Development of P.R.China,and also important for socially sustainable develop ment.Phytoremediation might remove metals from the soil more effectively compar ed to other methods.As the dominant location of metabolism in a plant cell,pro toplast can get respond greatly to the reaction signal to heavy metals,similar to that of the plant cell wall.Currently,it is also significant to further rev eal the remediation mechanism and response signal between plant protoplast and h eavy metals during the phytoremediation process,with spectral analysis methods than molecular diagnostic techniques.Calendula officinalis was obtained vi a pot experiments under l ead/cadmium contaminated soil,and the protoplast sample was derived with diffe rential centrifugation technology.Tessier’s Sequential Extraction Procedure-Atomic Absorption Spectrometry(AAS)was applied to study lead/cadmium speciatio n variation.The X-ray diffraction pattern(XRD),Fourier transform infrared spectroscopy(FTIR),two-dimensional infrared spectroscopy(2D-IR)and X-ray photoelectron spectroscopy(XPS)were used to investigate the spectral characte ristics of protoplast under different lead/cadmium contents.The results show:the exchangeable contents of lead/cadmium in protoplast are relatively low,an d the contents of cadmium with different speciation change little under differen t lead/cadmium concentrations in soil.The representative peak located at 31.7°in the XRD pattern,the evidence of sodium chloride crystal,and peaks of Pb_(5)(PO_(4))_(3)Cl and CdS could also be easily found.The dominant absorbance band i n FTIR spectra appears at 3510 cm^(-1),caused by the vibration of—OH.T he peak becomes complicated and moves to some extent,and functional groups of—OH and C O show a preferential combination to lead/cad mium,indicated from 2D-IR spectra.The elemental binding energies of C and O vary during the reaction in XPS spectra.The binding energy of C(1 s)incre ases,and C atoms involve in complexation.The moving peak of O(1 s)suggest s the reaction nature might be complex.The new peak of Pb(4 f)is caused by the interaction ofπelectron and lead ions.The binding energy of Cd(3 d)increases at higher lead/cadmium contents,and cadmium would lose electrons dur ing the reaction.The achievements,together with the results related to metal s and Calendula officinalis cell wall obtained previously,will play an imp orta nt role in the theory and technological improvement of phytoremediation.