Plants acquire essential nutrients from the soil through their roots. In the process, they may absorb many antibiotics such as kanamycin that are harmful to plants. Therefore plants such as Arabidopsis have evolved resistance mechanisms that involve the adjustment of metal uptake. We propose a model in which IREG1 is a transporter involved in Fe-citrate loading of the xylem while FRD3 is involved in the transport of citrate. In addition, when plants are exposed to kanamycin, IREG1 is inhibited. To test the model, we analyzed the growth and metal uptake of IREG1 and FRD3 mutants. We predict that if IREG1 is inhibited by kanamycin then there should be little effect of kanamycin on IREG1 mutants. While for FRD3 mutants we would expect a mild effect of kanamycin on growth and iron uptake. Our results showed that IREG1 mutants were severely affected by kanamycin, suggesting that an iron transporter other than IREG1 is inhibited by kanamycin. This finding will lead us to revise our model and identify an additional transporter that affects metal transport in the presence of kanamycin.
