Exposure of Lemna minor L. to gentian violet or Congo red is associated with changes in the biosynthesis pathway of biogenic amines.

In the literature, there is a lack of data on the effect of gentian violet (GV) and congo red (CR) dyes on the biosynthesis pathway of biogenic amines (BAs) in Lemna minor L. (common duckweed). This plant species is an important link in the food chain. Both dyes inhibited growth, biomass yield and the biosynthesis of chlorophyll a in common duckweed. The predicted toxic units demonstrated that GV had a more toxic effect on the growth rate and biomass yield of common duckweed than CR. Decarboxylase activity in the biosynthesis of BAs in common duckweed is also a useful indicator for evaluating the toxicity of both dyes. Gentian violet also exerted more phytotoxic effects on the analyzed biochemical features of common duckweed because it changed the putrescine (Put) biosynthesis pathway, increased tyramine content 1.6 fold, inhibited the activity of S-adenosylmethionine decarboxylase by 40% and the activity of ornithine decarboxylase (ODC) by 80%. Tyrosine decarboxylase (TDC) was most active in plants exposed to the highest concentration of GV. Similarly to control plants, in common duckweed exposed to CR, Put was synthesized from ornithine; however, spermidine content was 86% higher, Put content was 51% lower, and ODC activity was 86% lower.

Long-term responses of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) to the contamination of light soils with diesel oil.

Research into trees plays a very important role in evaluations of soil contamination with diesel oil. Trees are ideal for reclaiming contaminated soils because their large biomass renders them more resistant to higher concentrations of pollutants. In the literature, there is a general scarcity of long-term studies performed on trees, in particular European beeches. The aim of this study was to evaluate the responses of Scots pines and European beeches grown for 8 years on soil contaminated with diesel oil. Selected morphological and physiological parameters of trees were analyzed. The biomass yield of Scots pines was not significantly correlated with increasing concentrations of diesel oil, but it was more than 700% higher than in European beeches. Scots pines were taller and had a larger stem diameter than European beeches during the 8-year study. The diameter of trees grown on the most contaminated soil was reduced 1.5-fold in Scots pines and more than twofold in European beeches. The length of Scots pine needles from the most contaminated treatment decreased by 50% relative to control needles. The shortest needles were heaviest. The fluctuating asymmetry (FA) of needle length was highest in Scots pines grown on the most contaminated soil, whereas the reverse was noted in the FA of needle weight. Diesel oil decreased the concentrations of chlorophylls a and b, total chlorophyll, and carotenoids. The Fv/Fm ratio of needles and leaves was influenced by the tested concentrations of diesel oil. The results of the study indicate that the Scots pine better adapts (grows more rapidly and produces higher biomass) to long-term soil contamination with diesel oil than the European beech. In European beeches, growth inhibition and leaf discoloration (a decrease in chlorophyll content) were observed already after the first year of the experiment, which indicates that 1-year-old seedlings of European beech are robust bioindicators of soil contamination with diesel oil.

The effects of glyphosate-based herbicide formulations on Lemna minor, a non-target species.

Research into plants plays an important role in evaluations of water pollution with pesticides. Lemna minor (common duckweed) is widely used as an indicator organism in environmental risk assessments. The aim of this study was to determine by biological Lemna test and chemical methods the effect of glyphosate (GlyPh) concentrations of 0-40 µM on duckweed, an important link in the food chain. There are no published data on glyphosate's effects on the activity of enzymes of the amine biosynthesis pathway: ornithine decarboxylase, S-adenosylmethionine decarboxylase, tyrosine decarboxylase, lysine decarboxylase and arginine decarboxylase, and the content of shikimic acid and glyphosate residues in the tissues of common duckweed. It was found that glyphosate was taken up by duckweed. In plants exposed to 3 µM of glyphosate for 7 days, glyphosate content exceeded the acceptable Maximum Residue Level (MRL) 10-fold. Glyphosate accumulation in plant tissues exerted toxic effects on duckweed by decreasing its growth and yield, inhibiting the synthesis of chlorophyll a and b and carotenoids, and decreasing the photochemical activity of photosystem II (PSII). However, glyphosate increased the concentration of shikimic acid in the tested plants. The activity of ornithine decarboxylase increased 4-fold in plants exposed to 20 µM of the herbicide. As a water pollutant, glyphosate increased the content of biogenic amines tyramine, putrescine, cadaverine, spermidine and spermine. The activity of peroxidase and catalase was highest in duckweed exposed to 20 µM and 7 µM of the herbicide, respectively. The predicted toxic units were calculated based on glyphosate content and the computed EC values. The mean effective concentration calculated for all morphological and biochemical parameters of duckweed was determined at EC10 = 1.55, EC25 = 3.36, EC50 = 6.62 and EC90 = 14.08 µM of glyphosate. The study demonstrated that glyphosate, the active ingredient of Roundup Ultra 360 SL herbicide, induces morphological and biochemical changes in non-target plants and exerts toxic effects on aquatic ecosystems even during short-term exposure.

Uptake and reaction to roundup ultra 360 SL in soybean seedlings.

Due to the widespread and frequent use of Roundup Ultra 360 SL in crops production, the active substance glyphosate is often present (in the soil or in post-harvest remnants) and may be toxic to plants, including the non-target species. The aim of the current study was to determine the sensitivity of young soybean seedlings to glyphosate in concentrations ranging from 0 to 10 µM. It was demonstrated that the seedlings take small quantities of soil glyphosate up. More of the active substance was found in the shoots than in the roots. From the doses applied, the plant absorbs up to 4% of soil glyphosate, while over 96% remains in the soil. This suggests that only 4% of glyphosate taken up from the soil affects plant seedling development and water management. It modifies the contents of the biogenic amines cadaverine and putrescine as well as the activity of enzymes involved in their biosynthesis, i.e. ornithine decarboxylase and lysine decarboxylase. The free radical content of the roots increased with increasing herbicide doses and time of exposure. The main enzyme involved in the rapid removal of free radicals was superoxide peroxidase, activated by the herbicide treatment, while catalase was not significantly stimulated.

Recovery of Lemna minor after exposure to sulfadimethoxine irradiated and non-irradiated in a solar simulator.

Sulfonamides are the second most widely used group of veterinary antibiotics which are often detected in the environment. They are eliminated from freshwaters mainly through photochemical degradation. The toxicity of sulfadimethoxine (SDM) was evaluated with the use of Lemna minor before and after 1- and 4-h irradiation in a SunTest CPS+ solar simulator. Eight endpoints consisting of: number and total area of fronds, fresh weight, chlorophylls a and b, carotenoids, activity of catalase and guaiacol peroxidase, and protein content were determined. The total frond area and chlorophyll b content were the most sensitive endpoints with EC50 of 478 and 554 µg  L-1, respectively. The activity of guaiacol peroxidase and catalase increased at SDM concentrations higher than 125 and 500 µg  L-1, respectively. The SDM photodegradation rate for first order kinetics and the half-life were 0.259 h-1 and 2.67  h, respectively. The results show that the toxicity of irradiated solutions was caused by SDM only, and the photoproducts appeared to be either non-toxic or much less toxic to L. minor than the parent compound. To study the recovery potential of L. minor, after 7 days exposure in SDM solutions, the plants were transferred to fresh medium and incubated for the next 7 days. L. minor has the ability to regenerate, but a 7-day recovery phase is not sufficient for it to return to an optimal physiological state.

Content of biogenic amines in Lemna minor (common duckweed) growing in medium contaminated with tetracycline.

Aquatic plants are continuously exposed to a variety of stress factors. No data on the impact of antibiotics on the biogenic amines in duckweed (Lemna minor) have been available so far, and such data could be significant, considering the ecological role of this plant in animal food chains. In the tissues of control (non-stressed) nine-day-old duckweed, the following biogenic amines were identified: tyramine, putrescine, cadaverine, spermidine and spermine. Based on the tetracycline contents and the computed EC values, the predicted toxicity units have been calculated. The obtained results demonstrated phytoxicity caused by tetracycline in relation to duckweed growth rate, yield and the contents of chlorophylls a and b. The carotenoid content was not modified by tetracycline. It was found that tetracycline as a water pollutant was a stress factor triggering an increase in the synthesis of amines. Tetracycline at 19, 39 and 78µM concentrations increased biogenic amine synthesis by 3.5 times. Although the content of tyramine increased fourteen times with the highest concentration of the drug (and of spermidine - only three-fold) the increase of spermidine was numerically the highest. Among the biogenic amines the most responsive to tetracycline were spermine and tyramine, while the least affected were putrescine and spermidine. Despite putrescine and spermidine being the least sensitive, their sum of contents increased five-fold compared to the control. These studies suggest that tetracycline in water reservoirs is taken up by L. minor as the antibiotic clearly modifies the metabolism of this plant and it may likely pose a risk.

Phytotoxicity of sulfamethazine soil pollutant to six legume plant species.

The effect of traces of sulfamethazine (SMZ) in soil (0.01, 0.1, 0.25, 1, 5, 15, and 20 mM) on cellular distribution of cytochrome c oxidase activity, shoot and root growth, and leachate electroconductivity was analyzed in germinating seeds of yellow lupin, pea, lentil, soybean, adzuki bean, and alfalfa. Results showed that a high activity of cytochrome c oxidase in mitochondria correlated with high seed vigor and viability. The appearance of necroses and root decay was associated with a decrease in the activity of mitochondrial cytochrome c oxidase but was accompanied by an increase in cytosolic cytochrome c oxidase activity. A short exposure period of seeds (3 and 6 d) to sulfamethazine did not influence germination. Elongation of roots and stems was more sensitive than germination rate as an indicator of soil contamination by sulfamethazine. Among all tested leguminous plants, yellow lupin was the most reliable bioindicator of SMZ contaminated soil.