Primary and secondary processes of photosynthesis in chloroplasts of Lemna minor under the effect of pharmaceuticals
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| Year of publication | 2019 |
| Type | Conference abstract |
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| Description | As highly specific biologically active substances, pharmaceuticals contaminate mainly aquatic ecosystems. Non-steroidal anti-inflammatory drug diclofenac (DCF) is one of the most common pharmaceuticals detected and monitored worldwide. Mechanisms of pharmaceutical action on biochemical and physiological processes determining the growth and development of plants as non-target organisms are still mostly unknown. Photosynthesis represents a central anabolic pathway in plants, which results in the production of oxygen and energy-rich organic compounds necessary for growth. Possible direct effect of DCF (1, 10, 100, and 1000 uM) on primary and secondary photosynthetic processes was assessed in chloroplasts isolated from Lemna minor. After 10 min exposure, already 1 and 10 uM DCF induced elevated production of reactive oxygen and nitrogen species (by 116% and 157%, respectively) and lipid peroxidation (by nearly seven times compared to the control). Nevertheless, responses of photosystems I and II (decrease in quantum yields FV/FM by 21% and PhiII by 44% compared to control, changes in NPQ values or changes in the redox state of P700 reaction centres) and Hill reaction activity (drop by up to 73%) were not found until 100 uM DCF treatment. RuBisCO activity was only lowered by 30% under 1000 uM DCF. Results demonstrate the ability of environmentally relevant DCF concentrations to induce oxidative stress in isolated duckweed chloroplasts; however, photosynthetic processes were affected considerably only by the highest DCF treatments. Even though the markers of oxidative stress were already detectable, the capability of defence mechanisms in chloroplasts was probably sufficient to avoid negative impact under low DCF treatments, but acute high concentrations of drugs in the environment can participate in the inhibition of photosynthesis. |
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