changes in glutathione s-transferase activity and zearalenone content in susceptible and tolerant wheat heads inoculated with fusarium graminearum, the causal agent of fusarium head scab

glutathione s-transferase (gst) activity pattern was determined in tolerant (cv. sumai#3) and susceptible (cv. falat) wheat heads inoculated with fusarium graminearum, the causal agent of head scab disease (fhb), during various developmental stages. gst specific activity exhibited a transient pattern in sumai#3 reaching a maximum level at the milk stage and declining thereafter. gst level in sumai#3 was three times greater than that in the susceptible cultivar. thin layer chromatography and densitometry were used to measure zearalenone (zen) content in fhb-inoculated wheat heads. zearalenone concentration reached a maximum level in sumai#3 at the milk stage and thereafter it declined. zen content in the susceptible wheat heads continued to increase and reached a maximum level at the ripening stage. there seems to be a correlation between the increased gst activity and significantly lower zen production in the tolerant wheat heads.