Figure 10.

Mg²⁺ Uptake in Wild-Type and RNAi Plants.

(A) Time course of Mg²⁺ uptake in the roots of wild-type and RNAi (line 8) plants. Plants were first grown on soil for 2 weeks and then transferred to hydroponic medium with 3 mM Mg²⁺ for 1 week, followed by growth in 0 mM Mg²⁺ hydroponic medium for another 1 week. The Mg²⁺-starved plants were then transferred to hydroponic medium containing 0.02 or 3 mM Mg²⁺ and incubated for the indicated times. Roots were harvested subsequently, and Mg²⁺ contents in the roots were determined by ICP-AES.

(B) and (C) Concentration-dependent Mg²⁺ uptake rates in roots of wild-type and RNAi (line 8) plants. Plants were cultured as described in (A). The Mg²⁺-starved plants were transferred to a hydroponic medium containing various Mg²⁺ concentrations for 1 h before roots were harvested, and Mg²⁺ contents were determined by ICP-AES.

(D) MGT6-dependent Mg²⁺ uptake. The value for MGT6-dependent Mg²⁺ uptake was calculated by subtracting Mg²⁺ uptake of RNAi plant roots from that of the wild-type roots. The data were fitted to a Michaelis-Menten function by nonlinear least-squares analysis.

Three independent experiments were performed, and values represent means ± se. DW, dry weight.