Pathways and Characteristics of Lead Uptake and Transportation in Rhus chinensis Mill

Rhus chinensis Mill is a potential plant for phytoremediation of Pb and is able to uptake a copious amount of Pb. However, little is known about the pathways and properties of Pb uptake in this plant. Here, controlled experiments were used to assess Pb uptake and translocation in R. chinensis. The whole time-kinetics of Pb uptake were divided into two stages: rapid uptake and slower accumulation, and the two processes were fitted with a linear model. The concentration-dependent kinetics of Pb uptake were characterized by a modified Michaelis-Menten equation. The K-m and V-max value of Pb influx in roots were 19.44 and 14.83, respectively. Transpiration inhibitors had no significant effect on the Pb concentration of root and shoot. Low temperatures (4 degrees C) and metabolic inhibitors (carbonyl cyanide m-chlorophenylhydrazone and 2,4-dinitrophenol) significantly reduced the Pb concentration in the roots and leaves of R. chinensis plants. Furthermore, the addition of calcium ion channel inhibitors and protein synthesis inhibitors significantly reduced the Pb concentration in the roots of R. chinensis plants. These results show that both active and passive processes of Pb uptake and translocation exist in the roots of R. chinensis plants. In addition, Pb uptake by the roots of R. chinensis plants was related to calcium ion channels.