Bioindication Of Microcystins Toxicity By Germinating Seeds
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Z. Romanowska-Duda B., M. Grzesik, J. T. Mankiewicz & M. Zalewski
The effects of microcystins, produced by Microcystis aeruginosa PCC 7820, on seed germination, seedling growth, activity of selected enzymes and membrane permeability were evaluated, in order to elaborate the biotests for natural solution toxicity indication in water reservoirs. Commercial seeds of four selected species were allowed to germinate at 20 o C on filter paper moistened with: (i) water (control), (ii) three concentrations of microcystins cultures produced by Microcystis aeruginosa PCC 7820 or (iii) medium BG11 in which these cultures were conducted. To evaluate the sensitivity of these seeds to microcystins the number of the germinated seeds were counted and the length of roots and hypocotyls were measured 1, 2 and 3 days after sowing, while activity of RN-ase, phosphatase (pH 6.0 and pH 7.5), dehydrogenases and electrolyte leakage were measured after 8 and 24 hours of seed exposition in these compounds. The results showed that microcystins did not decrease significantly germination percentage and mean germination time of the tested seeds, except of L. sativa where the number of the germinated seeds was slightly reduced. A toxic effect of these solutions was exhibited by decreased root length in all germinated seeds, while hypocotyls length was not significantly affected by them. Microcystins also decreased the activity of the investigated enzymes and increased electrolyte leakage measured 8 and 24 hours after sowing. The research showed that growth of roots and activity of RN-ase, phosphatase (pH 6.0 and pH 7.5) or dehydrogenases, as well as electrolyte leakage from germinating seeds of selected species could be used for fast monitoring of the microcystin toxicity in water. Keywords: germination, microcystins, monitoring, toxicity, seeds, Sinapis alba, Cardamine sp., Lactuca sativa, Sorghum saccharatum.
germination, microcystins, monitoring, toxicity, seeds, Sinapis alba, Cardamine sp., Lactuca sativa, Sorghum saccharatum.