A yeast based screening method for Arabidopsis zearalenone-metabolism mutants

Arabidopsis thaliana and other plants are able to rapidly metabolize the estrogenic Fusarium metabolite zearalenone (ZON) into ZON-glucoside and further unknown compounds. We present here a rapid and efficient method to screen for Arabidopsis mutants unable to metabolize ZON. Arabidopsis seedling are grown in 96 well microtiter plates and subsequently incubated with ZON and β-glucosidase. The remaining ZON in the supernatant is detected with an engineered estrogen-responsive yeast strain. Extracellular ZON-4- O-glucoside (ZON-Glc), which is not detected by the indicator strain, is converted back to ZON by the added almond β-glucosidase. Wildtype Arabidopsis seedlings inactivate 2 ppm ZON in three days, which is easily detected by the colorimetric readout. The assay should be useful to identify mutants affected in ZON metabolism.