NaCl胁迫下苋菜中镉的亚细胞分布及转运研究  

Subcellular Distribution and Translocation of Cd in Amaranth under Salinity Stress

作　　者：周丽珍[1,2] 罗璇[1,2] 何宝燕[1,2] 李取生[1,2] 徐智敏[1,2] 陈艳芳[1,2] 余丹萍[1,2] 

机构地区：[1]暨南大学环境学院,广东广州510632 [2]水土环境毒害性污染物防治与生物修复广东省高校重点实验室,广东广州510632

出　　处：《生态环境学报》2015年第1期139-145,共7页Ecology and Environmental Sciences

基　　金：国家自然科学基金项目(41371321);中央高校基本科研基金项目(21612103)

摘　　要：中国大面积的农田土壤面临盐渍化和重金属的双重污染。探索盐分胁迫下作物可食部分的重金属累积特征将为保障农产品安全提供科学依据。本文主要从镉的亚细胞分布和离子选择性角度探讨盐分胁迫对苋菜（Amaranthus mangostanus L.）镉转运过程的影响。本试验采用水培苋菜的方式,添加不同质量浓度（0、2.5、5.0、7.5和10.0 g·L^-1）Na Cl和3.0μg·L^-1Cd处理,测定台湾白苋菜（耐盐型）和尖叶青苋菜（敏感型）根、茎、叶中Cd和Ca的亚细胞质量分数变化。Cd的亚细胞组分质量分数由大到小顺序均为：细胞壁（FI）〉细胞器（FII）〉〉细胞液（FIII）。Na Cl胁迫下,苋菜根、茎、叶中细胞壁（FI）和细胞器（FII）Cd质量分数总体显著下降,下降幅度为16%-71%,胞液（FIII）Cd质量分数基本不变,这主要和Na的竞争吸附和吸收有关。同时耐盐型台湾白苋菜根细胞器,茎、叶细胞壁和细胞器Ca质量分数总体下降,下降范围为20%-70%。敏感型尖叶青苋菜根、茎细胞壁和细胞器组分Ca质量分数均显著下降,叶细胞壁Ca质量分数下降幅度高达80%,说明细胞壁和质膜的生理结构和组成可能发生了变化;另一方面,苋菜的运输选择性比例TSK.Na（根-茎）、TSCa.Na（根-茎）和TSMg.Na（根-茎）显著下降,下降幅度达50%以上,TSK.Na（茎-叶）、TSCa.Na（茎-叶）和TSMg.Na（茎-叶）相较对照急剧上升,上升幅度均在44%以上,表明苋菜根部K、Ca、Mg向茎转移的选择性减弱;而茎向叶转移的选择性增强。苋菜细胞组成和离子选择性的变化使根、茎中细胞壁和细胞器对Cd的截留能力变差,Cd向地上部转移的比例增大,Cd在苋菜的转运系数TF（根-茎）、TF（茎-叶）较对照处理呈现不同程度的上升。台湾白苋菜的TF（根-茎）大于尖叶青苋菜,而TF（茎-叶）小于尖叶青苋菜,表明敏感型苋菜茎细胞对Cd截留能力较强,而耐盐型苋菜�Currently, the extensive agricultural soils in china are facing salinization and heavy metal pollution. Investigating the uptake and accumulation of heavy metal in the edible part of the crop under salt stress will provide scientific basis for agricultural food safety. This study aims to study the effect of salinity on Cd translocation in amaranth（Amaranthus mangostanus L.） in the view of subcellular distribution and ionic selectivity. A hydroponic experiment was performed on salt-tolerant（Taiwanbai） and salt-sensitive（Jianyeqin） cultivars under different salinity stress（0, 2.5, 5.0, 7.5 and 10.0 g·L^-1）and 3.0 μg·L^-1 Cd, the mass fraction of Cd and Ca in roots, stems and leafs were determined at subcellular level. The Cd mass fraction was in the order： cell wallorganellecytosol. Under salinity stress, Cd mass fraction of cell wall and organelle overall declined 16%-71% and cytosol Cd kept constant, which was closely related to competitive adsorption of Na. Ca mass fraction of cell walls and organelles in salt-tolerant cultivar decreased obviously, ranging from 20%-70%. Ca mass fraction of cell walls and organelles of root, stem components and leaf cell wall in salt-sensitive cultivar also decreased, and that of the leaf cell wall declined as much as 80%, suggesting that cell wall and plasma membrane possibly varied in constitutes and construction. On the other hand, the transport selectivity ratios TSK. Na（root-shoot）, TSCa. Na（root-shoot） and TSMg. Na（root-shoot） descended more than 50%, while TSK. Na（shoot-leaf）, TSCa. Na（shoot-leaf） and TSMg. Na（shoot-leaf） improved above 44% compared to the control. The varying cell constitutes and ionic selectivity of roots and shoots made the Cd retention capacity of cell wall and organelle weaker and translocation factors of Cd increase. The TF（root-shoot） of salt-tolerant cultivar is greater than salt-sensitive cultivar, while opposite situation is presented on TF（shoot-leaf）. It suggests that salt-sensitive amaranth

关 键 词：盐分 苋菜 镉 亚细胞分布 转运 

分 类 号：X171.5[环境科学与工程—环境科学]