摘要
植物细胞是植物响应重金属胁迫的重要生化反应场所,探索细胞层级中铅(Pb)的分布与形态转化是揭示有害元素对蔬菜毒性作用机理的重要途径。本研究以芹菜为例,利用能量色散透射电子显微镜(TEMEDS)和X射线吸收近边结构谱(XANES)技术,考察了Pb胁迫后芹菜根细胞的超微结构、元素分布和形态转化。研究发现,Pb胁迫显著改变了芹菜根细胞的超微结构,导致胞间间隙加大、细胞壁增厚和质膜变糙;芹菜根、茎和叶对Pb具有显著且不同的形态转化功能,可将无机铅(Pb(NO_3)_2)转化为有机铅形态;芹菜根细胞中62.7%的Pb以Pb_5(PO_4)_3Cl形态沉积在根细胞壁,根和茎中有机铅(Pb(Ac)_2·3H_2O)约占34.4%~37.3%,叶中总有机铅(Pb(C_(17)H_(35)COO)_2和Pb(Ac)_2·3H_2O)占63.3%。结果表明,芹菜细胞的Pb-磷酸盐来源于植物体的生物合成,而非外界根际环境,芹菜根际环境的Pb能够以Pb-Ac的络合物形式进入根细胞,一部分转化成Pb_5(PO_4)_3Cl沉积于细胞壁,实现Pb的解毒和耐受,少部分经茎长程运输至叶片以Pb-大分子有机酸/磷酸盐的形式贮存。
Plant cells are important biochemical reaction sites for responding to heavy metal stress.Exploring the distribution and speciation of lead(Pb)in celery at the cellular level is an important way to reveal the toxic mechanism of harmful elements on vegetables.In this study,ultrastructural alterations,localization of Pb in root cell and Pb speciation in celery were investigated by energy dispersive transmission electron microscopy(TEM-EDS)and X-ray absorption near edge spectroscopy(XANES).The result showed that Pb stress significantly changed the ultrastructure of celery root cells,increased intercellular spaces,thickened cell walls,and roughened plasma membrane.The roots,stems and leaves of celery had different speciation transformation functions for Pb,which could convert inorganic lead(Pb(NO 3)2)into organic lead form.About 62.7%of Pb in celery root cells deposited in the cell wall as the form of Pb 5(PO 4)3Cl,which showed the tolerance and detoxification of plant for Pb.The organic lead(Pb(Ac)2·3H 2O)in roots and stems were approximately from 34.4 to 37.3%,while total organic lead(Pb(C 17 H 35 COO)2 and Pb(Ac)2·3H 2O)in leaves accounted for 63.3%.This study indicated that Pb-phosphate in plant cells was derived from the biosynthesis by plants rather than the external rhizosphere environment.Pb in the rhizosphere of celery could enter the root cell as the form of Pb-Ac complex,and a part of Pb was converted into Pb 5(PO 4)3Cl deposition in the cell wall to detoxify and tolerate of Pb,and a small part of Pb was transported to the leaves and accumulated as the form of macromolecular Pb-organic acid and Pb-phosphate.
作者
柳检
罗立强
LIU Jian;LUO Li-Qiang(National Research Center for Geoanalysis,Beijing 100037,China)
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2018年第9期1479-1485,共7页
Chinese Journal of Analytical Chemistry
基金
国家重点研发计划项目(No.2016YFC0600603)
国家自然科学基金项目(Nos.20775018
41201527)
国家高新技术研究发展计划(863)项目(No.2007AA06Z124)
中国地质调查项目(No.DD20160340)资助~~
关键词
蔬菜
细胞
超微结构
铅形态
X-射线吸收近边结构谱
Vegetable
Cell
Ultrastructure
Lead speciation
X-ray absorption near edge spectroscopy
