Effects of light and CO2 on victorin-induced symptom development in oats

Victorin is a host-selective toxin produced by Cochliobolus victoriae the c ausal agent of victoria blight of oats. Victorin-binding and biochemical an alyses have implicated the glycine decarboxylase complex (GDC), a key compo nent of the photorespiratory cycle, as a possible site of action of the tox in. Plant dependence on a functional GDC is greatest under photorespiratory conditions and photorespiratory activity is increased with increasing ligh t and decreased with increasing concentrations of CO2. We have found that b oth low light and increased CO2 concentrations reduce the extent of victori n-induced symptom development in sensitive oats. These data provide physiol ogical evidence that the GDC is a biologically significant site of action o f victorin. (C) 1999 Academic Press.