Elevated copper concentrations effect on transcript levels of sulfate transporters and APS reductase in Chinese cabbage

Exposure of plants to excessive toxic metals might affect the regulation of uptake and assimilation of sulfate due to their reaction with sulfur metabolites. Exposure of Chinese cabbage to enhanced Cu2+ concentrations (5 and 10 µM) resulted in an increase in total sulfur content in the shoot which was most likely due to an accumulation of sulfate. The Group 1 sulfate transporters are involved in the primary uptake of sulfate by the roots. The results showed that Sultr1.1 was hardly expressed in both shoot and roots of Chinese cabbage. The expression of Sultr1;2 in roots was significantly enhanced at 10 µM Cu2+ concentration which was accompanied by an increase in the total sulfur content in the shoot. However, the expression of Sultr1;2 in the shoot was hardly changed by increasing Cu2+ content. Likewise, the expression of APS reductase, as a key enzyme in the sulfur assimilation pathway, was significantly increased in the roots however that of the shoot has been hardly altered at elevated Cu2+ concentration. The upregulation of the sulfate transporters and APS reductase may indicates the greater sulfur demand at elevated Cu2+ content. In addition it probably shows the interfering of the Cu with the signal transduction pathway regulating the expression of the sulfate transporters and sulfur metabolism-related gene.

Keywords:

APS reductase , Chinese cabbage , copper , sulfate transporters