中科院青岛生物能源与过程研究所丨浮萍超富集Cd的分子机制研究

NMT是基因功能的活体检测技术，已被31位诺贝尔奖得主所在单位，及北大、清华、中科院使用。

期刊：Chemosphere

主题：浮萍超富集Cd的分子机制研究

标题：Comparative transcriptome analysis of duckweed   (Landoltia punctata) in response to cadmium provides insights into   molecular mechanisms underlying hyperaccumulation

影响因子：4.427

检测指标：Cd2+流速

检测样品：浮萍根（根尖、距离根尖400μm，1000μm）

Cd2+流速流实验处理方法：

50 μM CdCl2处理30min

Cd2+流速流实验测试液成份：
0.1 mM KCl，0.1 mM MgCl2、0.05 mM CaCl2、0.3 mM MES、50μM CdCl2，pH5.5

作者：中科院青岛生物能源与过程研究所周功克、徐华

英文摘要

Cadmium (Cd) is a detrimental environmental   pollutant. Duckweeds have been considered promising candidates for Cd   phytoremediation. Although many physiological studies have been   conducted, the molecular mechanisms underlying Cd hyperaccumulation in   duckweeds are largely unknown.

In this study, clone 6001 of  Landoltia punctata, which showed high Cd tolerance, was obtained by  large-scale screening of over 200 duckweed clones. Subsequently, its  growth, Cd flux, Cd accumulation, and Cd distribution characteristics  were investigated. To further explore the global molecular mechanism, a  comprehensive transcriptome analysis was performed. For RNA-Seq, samples  were treated with 20 μM CdCl2 for 0, 1, 3, and 6 days.

In total,  9,461, 9,847, and 9615 differentially expressed unigenes (DEGs) were  discovered between Cd-treated and control (0 day) samples. DEG  clustering and enrichment analysis identified several biological   processes for coping with Cd stress. Genes involved in DNA repair acted as an early response to Cd, while RNA and protein metabolism would be   likely to respond as well.

Furthermore, the carbohydrate  metabolic flux tended to be modulated in response to Cd stress, and  upregulated genes involved in sulfur and ROS metabolism might cause high  Cd tolerance. Vacuolar sequestration most likely played an important  role in Cd detoxification in L. punctata 6001. These novel findings  provided important clues for molecular assisted screening and breeding  of Cd hyperaccumulating cultivars for phytoremediation.

中文摘要（谷歌机翻）

镉（Cd）是有害的环境污染物。浮萍被认为是镉植物修复的有前途的候选人。尽管已进行了许多生理研究，但浮萍中Cd过度富集的分子机制尚不清楚。

在这项研究中，通过大规模筛选200多个浮萍克隆，获得了对镉具有高耐受性的Landoltia   punctata克隆6001。随后，研究了其生长，Cd通量，Cd积累和Cd分布特征。为了进一步探索全局分子机制，进行了全面的转录组分析。对于RNA-Seq，样品用20μMCdCl2处理0、1、3和6天。

在经镉处理的样品和对照（0天）样品之间总共发现了9,461、9,847和9615个差异表达的单基因（DEG）。 DEG聚类和富集分析确定了应对Cd胁迫的几种生物学过程。参与DNA修复的基因是对Cd的早期反应，而RNA和蛋白质代谢也可能也有响应。

此外，碳水化合物的代谢通量倾向于响应Cd胁迫而被调节，而参与硫和ROS代谢的基因上调可能导致对Cd的高耐受性。液泡螯合最有可能在点球藻6001的Cd解毒中发挥重要作用。这些新发现为分子辅助筛选和育种Cd超富集植物进行植物修复提供了重要线索。

结果表明：叶片（F）的Cd2+吸收速率高于根冠（R0和R1），低于根伸长区（R2）。叶片中，从节点（F2）到顶点（F0）的Cd2+吸收速率逐渐下降。根和叶片的Cd2+吸收速率显著较低,从而更容易适应Cd胁迫。