Effects of mycorrhizal inoculation of upland rice on uptake kinetics of arsenate and arsenite

We assessed the effect of mycorrhizal inoculation on short-term uptake kinetics of arsenate and arsenite by excised roots of upland rice (Oryza sativa L. cv. Zhonghan 221). A concentration of 0.01-0.05 mM arsenic (As) differentially affected the influx rates of both arsenate and arsenite into rice roots non-inoculated or inoculated with Glomus mosseae and G. versiforme. While V_max for arsenate uptake by non-mycorrhizal roots was 1.02 μmol g^-1 fresh weight h^-1, it was reduced by a factor of 2.4 for mycorrhizal roots (about 0.42 μmol g^-1 fresh weight h^-1) in the high-affinity uptake system. However, at high concentrations of 0.5-2.5 mM As only G. versiforme was able to reduce As influx. The results show that mycorrhizal effects on As uptake of upland rice are both concentration and species-specific. Copyright