Institute of Botany, Jiangsu Province and Chinese Academy of Science, Nanjing 210014, China.
College of Horticulture, Nanjing Agricultural University Nanjing 210014, China.
Ecotoxicol Environ Saf. 2014 Jul;105:22-8. doi: 10.1016/j.ecoenv.2014.04.002. Epub 2014 May 7.
Metallothioneins (MTs) are cysteine-rich, low molecular weight, heavy metal-binding protein molecules. Here, a full-length cDNA homologue of MT2a (type 2 metallothionein) was isolated from the cadmium-tolerant species Iris. lactea var. chinensis (I. lactea var. chinensis). Expression of IlMT2a in I. lactea var. chinensis roots and leaves was up-regulated in response to cadmium stress. When the gene was constitutively expressed in Arabidopsis thaliana (A. thaliana), root length of transgenic lines was longer than that of wild-type under 50μM or 100μM cadmium stress. However, there was no difference of cadmium absorption between wild-type and trangenic lines. Histochemical staining by 3,3-diaminobenzidine (DAB) and nitroblue tetrazoliu (NBT) clearly demonstrated that transgenic lines accumulated remarkably less H2O2 and O2(-) than wild-type. Together, IlMT2a may be a promising gene for the cadmium tolerance improvement.
金属硫蛋白（MTs）是富含半胱氨酸、分子量低、重金属结合蛋白分子。在这里，从镉耐受物种萱草（Iris. lactea var. chinensis）中分离出了 MT2a（2 型金属硫蛋白）的全长 cDNA 同源物。在萱草的根和叶中，IlMT2a 的表达在镉胁迫下被上调。当该基因在拟南芥（Arabidopsis thaliana）中组成型表达时，与野生型相比，在 50μM 或 100μM 镉胁迫下，转基因系的根长更长。然而，野生型和转基因系之间的镉吸收没有差异。3,3-二氨基联苯胺（DAB）和硝基蓝四唑（NBT）的组织化学染色清楚地表明，与野生型相比，转基因系积累的 H2O2 和 O2(-) 明显减少。总之，IlMT2a 可能是提高镉耐受性的有前途的基因。
