Kanamycin is an aminoglycoside antibiotic derived from the bacterium Streptomyces kanamyceticus. Previous research indicated that when plants are exposed to kanamycin, their iron uptake is reduced. In addition, when the antibiotic resistance gene WBC19 is mutated, they reduce zinc uptake. This relationship between antibiotics and metal uptake appear to only hold true when there is citrate added to the media. We developed a model that takes into account the presence of citrate to explain these very different outcomes. We further test the model by examining the effect of kanamycin on Arabidopsis plants when no citrate is added to the media. Control and WBC19 mutants seedlings were grown on normal MS media containing 1Fe and 1Zn with no citrate added, and compared to seedlings grown with kanamycin present at 50 mg/l. Plant growth was monitored at days 7, 10, and 13 prior to harvesting them for metal uptake analysis. Our results show that with no added citrate, iron uptake in control plants was not severely reduced. In addition, in the WBC19 mutant plants zinc uptake was not significantly reduced. These results highlight the importance of citrate in modulating metal uptake and support our proposed model.
