Induction of S-nitrosoglutathione reductase reduces root cadmium uptake by inhibiting Iron-regulated transporter 1

Background and aimsIncreasing cadmium (Cd) contamination of agricultural soils is a serious problem. Identification of the mechanisms that control Cd uptake by roots is essential if we wish to improve the efficiency of plants in removing Cd from contaminated soils.MethodsWe dissected the role and the mechanism of S-nitrosoglutathione reductase (GSNOR) in regulating root Cd uptake in Arabidopsis plants using GSNOR-related mutants and pharmacological methods.ResultsExposure to Cd stimulated the activity of GSNOR in roots. Both treatment with S-nitrosoglutathione (substrate of GSNOR) in wild-type plants and loss of GSNOR function in gsnor mutants improved expression of IRON-REGULATED TRANSPORTER 1 (IRT1) and increased root Cd uptake, thereby elevating the Cd levels in plants. The opposite patterns were observed in the GSNOR over-expression transgenic plant GSNOR(OE), suggesting a negative regulation of IRT1 expression and Cd uptake by GSNOR. However, both the improvement of Cd uptake owing to S-nitrosoglutathione treatment or GSNOR mutation and the inhibition of Cd uptake due to GSNOR over-expression, could be blocked by loss of function of IRT1 in plants.ConclusionsWe concluded that induction of GSNOR reduced Cd uptake because of its negative regulation of IRT1 in roots, which lowered Cd accumulation in plants.