CIMMYT, Apdo. Postal 6-641, 06600 México, D.F., Mexico.
Metallomics. 2013 Sep;5(9):1305-15. doi: 10.1039/c3mt00084b.
Mercury (Hg) is a toxic metal that affects plant growth. Here the effect of Hg exposure on plant growth and leaf gas-exchange together with gene expression in roots is reported for barley. Hg was mainly accumulated in roots and only very small amounts were found in the shoots. Chlorophyll fluorescence and net photosynthesis were not affected by Hg. Nevertheless exposure to Hg reduced shoot and root growth, the shoot to root ratio, stomatal conductance, carbon isotope discrimination and expression of an aquaporin transcript, whereas abscisic acid related transcripts were over-expressed. These results suggested some degree of limitation to water uptake causing a moderate water stress when plants are exposed to Hg. Microarray (MapMan) analysis revealed changes in the transcription of genes involved in nitrogen metabolism, which were accompanied by decreased nitrogen concentrations in the shoots, together with an increase in transcripts associated with secondary metabolism, stress, inhibition of DNA synthesis/chromatin structure and cell organization elements. Moreover, Hg induced the expression of many transcripts known to be involved in the uptake, accumulation, transport and general responses to other heavy metals. It is concluded that barley is able to accumulate high amounts of Hg in roots through several transcriptional, metabolic and physiological adjustments.
汞（Hg）是一种有毒金属，会影响植物的生长。本研究报告了汞暴露对大麦植物生长和叶片气体交换以及根系基因表达的影响。汞主要积累在根部，只有很少量的汞出现在地上部分。汞暴露没有影响叶绿素荧光和净光合作用。然而，汞暴露降低了地上部分和根系的生长、地上部分与根系的比例、气孔导度、碳同位素分馏和水通道蛋白转录本的表达，而脱落酸相关转录本的表达则上调。这些结果表明，当植物暴露于汞时，可能会出现一定程度的水分吸收限制，导致中度的水分胁迫。微阵列（MapMan）分析显示，参与氮代谢的基因转录发生变化，伴随着地上部分氮浓度的降低，同时与次生代谢、胁迫、DNA 合成/染色质结构和细胞组织元素抑制相关的转录本增加。此外，汞诱导了许多已知参与其他重金属的吸收、积累、运输和一般响应的转录本的表达。研究结论认为，大麦通过几种转录、代谢和生理调节，能够在根部积累大量的汞。
