Subcellular compartmentation of strontium and zinc in mulberry idioblasts in relation to phytoremediation potential
Subcellular compartmentation of strontium and zinc in mulberry idioblasts in relation to phytoremediation potential
复制标题
DOI：
10.1016/j.envexpbot.2012.06.001
复制
发表时间：
2013
影响因子：
5.7
通讯作者：
H. Katayama;N. Banba;Y. Sugimura;M. Tatsumi;S. Kusakari;H. Oyama;A. Nakahira
中科院分区：
文献类型：
--
作者：
H. Katayama;N. Banba;Y. Sugimura;M. Tatsumi;S. Kusakari;H. Oyama;A. Nakahira
使用桑叶分析重金属的细胞区划，其中形成 CaCO3 的成体细胞位于表皮层。发芽的桑苗在含有锶 (Sr)、锌 (Zn) 和镉 (Cd)、添加和不添加钙 (Ca) 的水培培养基上生长。生长十周后，通过测量芽长度和叶子的叶绿素含量来评估这些金属的毒性作用。更高剂量的 Sr 和 Cd 处理（Sr 为 4mM，Cd 为 25μM）会导致毒性迹象，而 500μM Zn 则没有观察到明显的植物毒性。使用配备变压扫描电子显微镜的能量色散 X 射线微量分析系统对叶子进行元素图谱显示，Sr 和 Zn 优先积累在成体细胞中，并且在任何类型的叶细胞中均未检测到 Cd。 Sr 的沉积位点仅限于成纤维细胞中发育的细胞壁囊。叶片Sr库容量大于30mg/g干重，与Ca库容量相当。 Sr+Ca 的暴露导致 Sr 和 Ca 在同一细胞壁囊中共定位，其中 Ca 和 Sr 沉积量估计分别为 60-80ng。锌的定位位点是成虫细胞的圆顶状突起（帽）的细胞壁，以及源自培养自来水中污染物的硅（Si）。桑树成纤维细胞的独特之处在于，其两个亚细胞位点（细胞壁囊和帽区域）表现出金属依赖性分布。总之，桑树因其 Sr 超富集能力和足够的叶片生物量生产而成为放射性锶植物修复的候选者。
The cellular compartmentation of heavy metals was analyzed using mulberry leaves, in which CaCO3-forming idioblasts are situated in the epidermal layer. Germinated mulberry seedlings were grown on hydroponic culture medium containing strontium (Sr), zinc (Zn), and cadmium (Cd) with and without supplemental calcium (Ca). After ten weeks of growth, toxic effects of these metals were assessed by measuring shoot length and chlorophyll content of leaves. Sr and Cd treatment at a higher dose (4mM for Sr, 25μM for Cd) resulted in signs of toxicity, whereas no distinct phytotoxicity was observed at 500μM Zn. Elemental mapping of leaves using an energy-dispersive X-ray microanalysis system fitted to variable-pressure scanning electron microscope showed that Sr and Zn were preferentially accumulated in the idioblasts and Cd was not detected in any type of leaf cell. The deposition site of Sr was confined to cell wall sacs developing in idioblasts. The Sr sink capacity in leaves was more than 30mg/g dry weight, which equaled the Ca sink capacity. Exposure of Sr+Ca led to the co-localization of Sr and Ca in the same cell wall sac, in which Ca and Sr deposition were each estimated to be 60–80ng. The localization site of Zn was cell walls of a dome-shaped protrusion (cap) of idioblasts, together with silicon (Si) originating as a contaminant in tap water used for culturing. Mulberry idioblasts were unique in showing metal-dependent distribution to two subcellular sites (cell wall sac and cap region) of idioblasts. In conclusion, mulberry plant is a candidate for phytoremediation of radiostrontium because of their Sr-hyperaccumulating capacity with sufficient leaf biomass production.