Hernández-Allica J, Garbisu C, Becerril J M, Barrutia O, García-Plazaola J I, Zhao F J, Mcgrath S P
NEIKER, Basque Institute of Agricultural Research and Development, Berreaga 1, E-48160 Derio, Spain.
Plant Cell Environ. 2006 Jul;29(7):1422-9. doi: 10.1111/j.1365-3040.2006.01525.x.
In this study, we investigated the accumulation of phytochelatins (PCs) and other low molecular weight (LMW) thiols in response to Cd exposure in two contrasting ecotypes differing in Cd accumulation. Using a root elongation test, we found that the highly accumulating ecotype Ganges was more tolerant to Cd than the low Cd-accumulation ecotype Prayon. L-buthionine-(S,R)-sulphoximine (BSO), a potent inhibitor of the gamma-glutamylcysteine synthetase gamma-ECS) (an enzyme involved in the PC biosynthetic pathway), increased the Cd sensitivity of Prayon, but had no effect on Ganges. Although PC accumulation increased in response to Cd exposure, no significant differences were observed between the two ecotypes. Cd exposure induced a dose-dependent accumulation of both Cys and a still unidentified LMW thiol in roots of both ecotypes. Root accumulation of Cys and this thiol was higher in Ganges than in Prayon; the ecotypic differences were more pronounced when the plants were treated with BSO. These findings suggest that PCs do not contribute to the Cd hypertolerance displayed by the Ganges ecotype of Thlaspi caerulescens, whereas Cys and other LMW thiols might be involved.
在本研究中,我们调查了两种镉积累能力不同的生态型天蓝遏蓝菜在镉暴露下植物螯合肽(PCs)和其他低分子量(LMW)硫醇的积累情况。通过根伸长试验,我们发现高积累生态型恒河比低镉积累生态型普赖恩对镉更具耐受性。L-丁硫氨酸-(S,R)-亚砜亚胺(BSO)是γ-谷氨酰半胱氨酸合成酶(γ-ECS)(一种参与PC生物合成途径的酶)的有效抑制剂,它增加了普赖恩对镉的敏感性,但对恒河没有影响。尽管镉暴露后PC的积累增加,但在这两种生态型之间未观察到显著差异。镉暴露诱导了两种生态型根系中半胱氨酸(Cys)和一种仍未鉴定的LMW硫醇的剂量依赖性积累。恒河根系中Cys和这种硫醇的积累高于普赖恩;当用BSO处理植物时,生态型差异更为明显。这些发现表明,PCs对天蓝遏蓝菜恒河生态型所表现出的镉超耐受性没有贡献,而Cys和其他LMW硫醇可能参与其中。