Cyanobacterial Toxins Impact Crops

Oregon surface waters are experiencing increased occurrence of potentially toxic cyanobacterial blooms (Fig. 1). It is necessary to use the modifier “potentially” because there is no toxin monitoring in the state of Oregon. Advisories are currently based on cell counts of potentially harmful cyanobacteria. This summary is intended to briefly review the recent research on the effects of a cyanobacterial (a.k.a. Bluegreen algae) toxin, microcystin-LR on crop plants and highlight two human exposure routes important to Oregon consumers and growers. The toxin microcysyin-LR is one of many toxins (there are 70 analogs of microcystin alone) produced by cyanobacteria. Much of the research focuses on this compound because it is widespread, produced by many species of cyanobacteria and is hydrophobic. This may allow microcystin-LR to diffuse across cell membranes but the exact mechanism of uptake is not known. An extensive literature review [1] indicates that plants are generally not killed by realistic levels of cyanotoxins but, rather are growth inhibited, which lowers crop yields and unfortunately requires that we consider the possibility of human exposure via the consumption exposed plants.