Microcystins (MCs) are naturally occurring hepatotoxic cyclic heptapeptides produced by some toxic freshwater cyanobacterial species. In the study, the effects of MCs on the growth and the activities of antioxidant enzymes were investigated in Chinese cabbage and rape grown under different MCs concentration (equivalent to 0, 0.008, 0.04, 0.08, 0.4, 0.8 and 4 mg MC-LR L-1) conditions for 7 days. The results showed that exposure to MCs inhibited the growth and development of both Chinese cabbage and rape seedlings. However, MCs had more significant inhibition effect on Chinese cabbage than rape in growth and biomass. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) demonstrated that MCs stress was manifested as an oxidative stress. Using LC-MS, MCs was examined from the extract of exposed Chinese cabbage and rape seedlings, indicating that consumption of edible plants exposed to MCs via irrigation route might have health risks. Significantly different levels of recovered MCs between exposed Chinese cabbage and rape seedlings suggested that there might be different tolerant mechanisms toward MCs. The results showed that irrigation with water containing MCs has the potential to move MCs into farm animal and human food chains.
