Regulation of the Uptake of Sulfate by Chinese Cabbage (Brassica pekinensis) at Various Sulfate Concentrations in the Root Environment

If Chinese cabbage was grown hydroponically at various sulfate concentrations ranging from 5 to 100 mu M in the root environment, it was able to maintain its growth even at 5 and 10 mu M, concentrations close to the Km of the Group 1 high affinity sulfate transporters. The sulfate uptake capacity of the roots was up-regulated at <= 25 mu M sulfate, however, the expression of Sultr1;2, the primary sulfate transporter abundant in the root of Chinese cabbage, was hardly affected. There was no clear relation between the overall tissue levels of sulfate and thiols and the expression and activity of the sulfate transporters in root tissue upon variation in sulfate supply.