CONICET | Buscador de Institutos y Recursos Humanos

Background and aims: Recent studies indicate that Microcystins can affect plants by inhibiting their growth, although little is known about toxic power and action mechanisms of MC-LR on plants. MC-LR damages on animal systems focus on two main action mechanisms of the toxin: protein phosphatase inhibition (PP1 and PP2A) and ROS generation. The aim of this work is to study the toxic effects of a single exposure to different concentrations of MC-LR on Phaseolus vulgaris seeds during imbibition stage. Methods: MC-LR was purified from natural bloom of Microcystis aeruginosa and determined by HPLC. Four groups of 50 Phaseolus vulgaris seeds each were treated with 0 (control); 3.5; 15 and 30 ppm of MC-LR during imbibitions stage. 72 hours after treatment, macroscopic and histological studies of the roots were conducted. On roots and embryos homogenates determination of residual protein phosphatase activity and SDS-PAGE electrophoresis were carried out. Results and conclusions: Histological alterations were observed consistent with a decrease in germination rate of 41%, 71% and 94% for 3.5, 15 and 30 ppm of MC-LR treated seeds respectively. Also, there was a decrease in root length of 28% for seeds treated with 3.5 ppm of MC-LR and 50% for seeds treated with 15 and 30 ppm of MC-LR respect to control. The residual protein phosphatase activity were decreased in 15% for 3.5 ppm MC-LR treatment, 58% for 15 ppm MC-LR treatment and 67% for 30 ppm MC-LR treatment respect to control. Likewise proteins induction, which molecular weights matched with heat shock proteins (HSP 90, 60, 50, 40, 29, 20 and 14 kDa), were observed. These results indicate the need to consider the effects of MC-LR exposure in crops. It would also be interesting to continue studying these effects and observe their impact on crop yields.