title: Enhanced Heavy Metal Tolerance and Accumulation by Transgenic Sugar Beets Expressing Streptococcus thermophilus StGCS-GS in the Presence of Cd, Zn and Cu Alone or in Combination.
abstract: Phytoremediation is a promising means of ameliorating heavy metal pollution through the use of transgenic plants as artificial hyperaccumulators. A novel Streptococcus thermophilus γ-glutamylcysteine synthetase-glutathione synthetase (StGCS-GS) that synthesizes glutathione (GSH) with limited feedback inhibition was overexpressed in sugar beet (Beta vulgaris L.), yielding three transgenic lines (s2, s4 and s5) with enhanced tolerance to different concentrations of cadmium, zinc and copper, as indicated by their increased biomass, root length and relative growth compared with wild-type plants. Transgenic sugar beets accumulated more Cd, Zn and Cu ions in shoots than wild-type, as well as higher GSH and phytochelatin (PC) levels under different heavy metal stresses. This enhanced heavy metal tolerance and increased accumulation were likely due to the increased expression of StGCS-GS and consequent overproduction of both GSH and PC. Furthermore, when multiple heavy metal ions were present at the same time, transgenic sugar beets overexpressing StGCS-GS resisted two or three of the metal combinations (50 μM Cd-Zn, Cd-Cu, Zn-Cu and Cd-Zn-Cu), with greater absorption in shoots. Additionally, there was no obvious competition between metals. Overall, the results demonstrate the explicit role of StGCS-GS in enhancing Cd, Zn and Cu tolerance and accumulation in transgenic sugar beet, which may represent a highly promising new tool for phytoremediation.
authors.affiliation: Key Laboratory of Sugar beet Genetics and Breeding, Academy of Crop Sciences, Heilongjiang University, Harbin, 150080, P. R. China; Key Laboratory of Forest Plant Ecology, the Ministry of Education of China, Northeast Forestry University, Harbin, 150040, P. R. China.
authors.forename: Dali
authors.initials: D
authors.lastname: Liu
authors.affiliation: Key Laboratory of Forest Plant Ecology, the Ministry of Education of China, Northeast Forestry University, Harbin, 150040, P. R. China.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: An
authors.affiliation: Key Laboratory of Forest Plant Ecology, the Ministry of Education of China, Northeast Forestry University, Harbin, 150040, P. R. China.
authors.forename: Zijun
authors.initials: Z
authors.lastname: Mao
authors.affiliation: Key Laboratory of Sugar beet Genetics and Breeding, Academy of Crop Sciences, Heilongjiang University, Harbin, 150080, P. R. China.
authors.forename: Longbiao
authors.initials: L
authors.lastname: Ma
authors.affiliation: Key Laboratory of Biochemistry and Molecular Biology, College of Life Sciences, Heilongjiang University, Harbin, 150080, P. R. China.
authors.forename: Zhenqiang
authors.initials: Z
authors.lastname: Lu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D027461:Beta vulgaris / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D001711:Biotransformation; D004351:Drug Resistance; D019216:Metals, Heavy / Q000378:metabolism / Q000633:toxicity*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D048249:Streptococcus thermophilus / Q000235:genetics; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D019216:Metals, Heavy