Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing 210095, China.
J Hazard Mater. 2013 Apr 15;250-251:204-11. doi: 10.1016/j.jhazmat.2013.01.053. Epub 2013 Jan 31.
The toxic metal cadmium (Cd) constitutes one of the major inorganic contaminants in environments. microRNAs (miRNAs) are a class of endogenous non-coding small RNAs. miR395 is conserved and regulates sulfate assimilation and distribution in higher plants, but whether it is involved in detoxification of Cd in plants has not been described. In this study, transgenic rapeseed (Brassica napus) over-expressing miR395 was identified under Cd stress. miR395-over-expressing plants showed a lower degree of Cd-induced oxidative stress than wild type. By contrast, chlorophyll, glutathione and non-protein thiols contents were higher in the transformants than wild type. Determination of growth response showed that 35S::MIR395 plants accumulated higher levels of biomass and sulfur than wild type under Cd exposure. miR395 transgenic plants had higher levels of Cd in plants, particularly at the high supply of Cd in the medium, but they tended to repress Cd translocation from roots to shoots. Simultaneously, expression of metal-tolerance genes such as BnPCS1, BnHO1 and Sultr1;1 was up-regulated under Cd stress, and the expression of the genes was more pronounced in 35S::MIR395 plants than in wild type. These results suggest that miR395 would be involved in detoxification of Cd in B. napus.
有毒金属镉（Cd）是环境中主要的无机污染物之一。microRNAs（miRNAs）是一类内源性非编码小分子 RNA。miR395 在高等植物中保守，调节硫酸盐同化和分布，但它是否参与植物中 Cd 的解毒尚未描述。在这项研究中，在 Cd 胁迫下鉴定出了过表达 miR395 的转基因油菜（Brassica napus）。与野生型相比，过表达 miR395 的植物表现出较低程度的 Cd 诱导氧化应激。相比之下，转化体中的叶绿素、谷胱甘肽和非蛋白巯基含量高于野生型。生长反应的测定表明，在 Cd 暴露下，35S::MIR395 植物比野生型积累更高水平的生物量和硫。miR395 转基因植物在植物中积累了更高水平的 Cd，特别是在培养基中 Cd 供应较高的情况下，但它们倾向于抑制 Cd 从根部向地上部的转运。同时，金属耐受基因如 BnPCS1、BnHO1 和 Sultr1;1 的表达在 Cd 胁迫下上调，并且在 35S::MIR395 植物中的表达比野生型更为明显。这些结果表明，miR395 可能参与了油菜对 Cd 的解毒。
