Induction of active oxygen species (AOS), lipoxygenase and lipid peroxidation in suspension-cultured sugarcane cells by a glycoprotein elicitor isolated from Colletotrichum falcatum

The effect of an elicitor isolated from the mycelial walls of Colletotrichum falcatum, the red rot pathogen, in suspension-cultured cells of resistant ('BO 91') and susceptible ('CoC 671') sugarcane cultivars was studied. The elicitor rapidly induced the generation of H₂O₂ and O₂^- within 10 min after treatment in suspension-cultured cells of both resistant and susceptible cultivars. However, the generation of active oxygen species (AOS) was more rapid in suspension-cultured cells of resistant cultivar compared to that of the susceptible one. The level of lipid peroxidation in cell suspension of the resistant cultivar significantly increased 6 h after of elicitor treatment, whereas it increased only 12 h after treatment in the cells of the susceptible cultivar. Lipoxygenase (LOX) activity also significantly increased by 4 h after elicitor treatment in cultured cells of both resistant and susceptible cultivars. However, the increase in LOX activity in suspension cells of the resistant cultivar was greater compared to that of the susceptible one. Suspension-cultured cells of the susceptible cultivar constitutively expressed higher levels of superoxide dismutase (SOD) activity compared to that of the resistant cultivar. Elicitor treatment caused an increase in SOD activity in the susceptible cultivar, whereas in the resistant cultivar, it caused a decrease in SOD activity.