Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 8/10/2001
Publication Date: N/A
Technical Abstract: The mycotoxin, deoxynivalenol (DON) accumulates in wheat and barley heads infected with Fusarium graminearum. To assess the effects of DON on green plant tissues, we partially stripped the abaxial epidermis from detached Robust barley leaf segments (1 cm long) and floated them with stripped mesophyll in contact with aqueous DON solutions. In light (150-450 micro mol/m**2/sec), DON (30-200 ppm) caused complete loss of pigmentation in stripped mesophyll within 2-4 days. The greater the light intensity or the DON concentration, the more rapid was the bleaching effect. The bleached tissue was neither watersoaked nor collapsed, but chloroplasts and other cytoplasmic organelles became disorganized as observed by transmission electron microscopy. In darkness, DON at 30-100 ppm had an opposite effect, preserving chloroplasts, causing leaf segments to remain dark green for 6-7 days and preventing the yellowing that occurred in segments floated on water. Because of the opposing effects of DON in light and darkness, assays of plants for sensitivity to DON should include trials under both conditions.