To explore the possible roles of metallothioneins (MTs) played in cadmium (Cd) accumulation of water spinach, three IaMT genes, IaMT1, IaMT2 and IaMT3 in a high-shoot-Cd (T308) and a low-shoot-Cd accumulation cultivar (QLQ) were cloned, characterized, and quantitated. Gene expression analysis suggested that the expression of the IaMTs was differentially regulated by Cd stress in different cultivars, and T308 showed higher MTs expression overall. Furthermore, only shoot IaMT3 expression was cultivar dependent among the three IaMTs. Antioxidant analysis showed that the high production of IaMTs in T308 should be associated with its high oxidation resistance. The role of IaMTs in protecting against Cd toxicity was demonstrated in vitro via recombinant E. coli strains. The results showed that IaMT1 correlated with neither Cd tolerance nor Cd accumulation of E. coli, while IaMT2 conferred Cd tolerance in E. coli, IaMT2 and IaMT3 increased Cd accumulation in E. coli. These findings help to clarify the roles of IaMTs in Cd accumulation, and increase our understanding of the cultivar-dependent Cd accumulation in water spinach.

探讨中的可能作用金属硫蛋白（MT的）中镉扮演（CD）空心菜的积累，三个iAMT的基因，IAMT1，IaMT2和我一个MT3在高拍镉（T308）和低射击镉积累品种（QLQ）被克隆，鉴定和定量。基因表达分析表明，IaMTs的表达受不同品种的Cd胁迫的差异调节，而T308总体上表现出较高的MTs表达。此外，在三个IaMT中，只有芽IaMT3表达依赖于品种。抗氧化剂分析表明，T308中IaMT的高产量应与其高抗氧化性有关。通过重组大肠杆菌菌株在体外证明了IaMT在预防Cd毒性方面的作用。结果表明，IaMT1与大肠杆菌的Cd耐受性和Cd积累均不相关，而IaMT2赋予大肠杆菌Cd耐受性，IaMT2和IaMT3增加了大肠杆菌中Cd的积累。这些发现有助于阐明IaMT的作用 镉的积累，并增加了我们对水菠菜中依赖品种的镉积累的了解。