Špela Mechora

Distribution of Se and its species in Myriophyllum spicatum and Ceratophyllum demersum growing in water containing Se (VI).

The uptake of Se (VI) by two aquatic plants, Myriophyllum spicatum L. and Ceratophyllum demersum L., and its effects on their physiological characteristics have been studied. Plants were cultivated outdoors under semi-controlled conditions and in two concentrations of Na selenate solution (20 μg Se L(-1) and 10 mg Se L(-1)). The higher dose of Se reduced the photochemical efficiency of PSII in both species, while the lower dose had no effect on PSII. Addition of Se had no effect on the amounts of chlorophyll a and b. The concentration of Se in plants grown in 10 mg Se L(-1), averaged 212 ± 12 μg Seg(-1) DM in M. spicatum (grown from 8-13 d), and 492 ± 85 μg Se g(-1) DM in C. demersum (grown for 31 d). Both species could take up a large amount of Se. The amount of soluble Se compounds in enzyme extracts ranged from 16% to 26% in control, and in high Se solution from 48% to 36% in M. spicatum and C. demersum, respectively. Se-species were determined using HPLC-ICP-MS. The main soluble species in both plants was selenate (∼37%), while SeMet and SeMeSeCys were detected at trace levels.

The uptake and distribution of selenium in three aquatic plants grown in Se(IV) solution.

The uptake of Se(IV) by Myriophyllum spicatum, Ceratophyllum demersum and Potamogeton perfoliatus, and the effects of Se(IV) on their physiological and biochemical characteristics were studied. Plants were cultivated outdoors under semi-controlled conditions in water solution containing Na selenite (20 μg Se L(-1) and 10 mg Se L(-1)). The higher concentration of Se lowered the photochemical efficiency of PSII in all species studied, while the lower concentration had no effect on any species. The higher concentration of Se lowered respiratory potential in M. spicatum. The response of M. spicatum and C. demersum to Se(IV) regarding chlorophylls was variable, however in the majority of cases, there was a trend of increasing the amount of chlorophylls, while in P. perfoliatus the amount of chlorophyll a decreased. The concentration of Se in plants cultured in 10 mg Se(IV) L(-1) ranged from 436 to 839 μg Se g(-1) DM in M. spicatum, 319 to 988 μg Se g(-1) DM in C. demersum and 310 to 661 μg Se g(-1) DM in P. perfoliatus. The amount of soluble Se compounds in enzyme extracts of high Se treatment was 27% in M. spicatum, 41% in C. demersum and 35% in P. perfoliatus. Se compounds were determined using HPLC-ICP-MS. It was observed that the applied Se(IV) was mainly transformed to insoluble Se.

Selenium and its species in the aquatic moss Fontinalis antipyretica

The ability of the widely distributed aquatic moss Fontinalis antipyretica to take up Se from water was studied. Nine locations in the Notranjska region (Slovenia) with different land use in the catchment were sampled for water and moss in the year 2010 in spring, summer and autumn. The concentrations of Se in water at all locations did not exceed 0.2 ng mL(-1). F. antipyretica took up Se in the range between 345 and 2250 ng g(-1). All results for Se are expressed on dry matter basis. The Se content varied depending on the location and season. The highest concentration (2250 ± 170 ng g(-1)) of Se was found in the Žerovniščica stream that flows through an agricultural area with dairy farming. The fraction of insoluble Se compounds in the residue after enzymatic hydrolysis using protease (XIV) was around 75%. Soluble Se compounds in the enzymatic extract of F. antipyretica were separated and measured using HPLC coupled to ICP-MS. Se(IV) and Se(VI) were found but no organic Se compounds were detected, even at the highest concentration.

Impact of selenium on mitochondrial activity in young Tartary buckwheat plants

To investigate the impact of Se on Tartary buckwheat (Fagopyrum tataricum Gaertn.) plants, the plant foliage was sprayed with 10 mg Se(VI) L(-1) at the beginning of flowering. The Se was effectively assimilated by the plants and taken into the seeds, where its concentration was more than double that in untreated plants. The seeds were collected and sown to obtain the progeny of these Se-treated plants. To assess the physiological characteristics of control plants and these Se-treated progeny plants, the estimated respiratory potential via electron transport system (ETS) activity and the photochemical efficiency of photosystem II were measured. Three weeks after germination, the Se-treated progeny plants showed higher ETS activity compared to the controls. Through weeks 4 and 5, this high ETS activity approximately halved, and the difference in ETS activity seen at 3 weeks was lost. On the other hand, at week 4, the potential photochemical efficiency was higher in the Se-treated progeny plants than the controls. In adult plants, the leaves dry mass was significantly greater in the Se-treated progeny plants than the controls. This study demonstrates an impact of Se in Tartary buckwheat on the progeny plants of Se sprayed plants, as shown previously in pea plants.

Selenium compounds in selenium-enriched cabbage

For the study, cabbage (Brassica oleracea var. capitata L.) and red cabbage (Brassica oleracea var. capitata L. f. rubra) were treated with Na selenate. Cabbage was foliarly sprayed twice with 20 mg Se(VI) L–1, while red cabbage was fertilized twice with 0.5 mg Se(VI) L–1. Despite the high dose of Se, no toxic effects were observed on cabbage plants. The total Se concentration in cabbage leaves was 4.80 ± 0.25 μg Se g–1 (DM) and in red cabbage 0.96 ± 0.04 μg Se g–1 (DM). Soluble Se compounds were extracted from parts of cabbage with protease XIV, resulting in 49 % of soluble Se from roots, 59 % from leaves, and 65 % from stems. In red cabbage, the corresponding figures were 28 % of soluble Se in roots, 31 % in stems, and 43 % in leaves. Se species were determined in the enzymatic extracts using ion exchange high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). The main Se species found in all parts of cabbage and red cabbage was selenomethionine (SeMet), which in roots represented 94 and 55 % of the soluble Se content in cabbage and red cabbage, respectively. In stems and leaves of cabbage, SeMet represented only 23 % of the soluble Se content. In stems of red cabbage SeMet represented 80 % and in leaves 41 % of the soluble Se content. We observed that traces of Se(VI) were present in upper parts of both plants.

The Physiology and Biochemical Tolerance of Cabbage to Se (VI) Addition to the Soil and by Foliar Spraying

The effects of selenium (Se) (VI) soil fertilization with 2 μg Se L−1 or foliar spraying twice with 20 mg Se L−1 in the form of sodium (Na) selenate on the physiological and biochemical characteristics of cabbage plants were studied. The ability of the plants to take up Se and translocate it to different parts of the plants was also studied. Despite the high concentration of Se in the foliar solution, there was no effect on photosynthesis, transpiration rate, photochemical efficiency of PSII, or electron transport system activity. The amount of chlorophyll and anthocyanins were unchanged. At harvest, the concentration of Se in control plants was lower than 100 ng Se g−1 dry weight (DW), while plants treated with 20 mg Se L−1 contained 5500 ng Se g−1. Selenium enriched cabbage could be used in human nutrition. The tolerance of cabbage to Se could be explained by the formation of insoluble compounds that are not available for the plant.

Monitoring of selenium in macrophytes – The case of Slovenia

This paper examines macrophytes from various locations in Slovenian streams for selenium (Se) content in an attempt to discover if Se contamination is present and if Se uptake varies between sampling sites. For this purpose, macrophytes and water from ten locations in the Notranjska and Central regions (Slovenia) with different land use in the catchment were sampled. To assess the environmental conditions of the streams the Riparian, Channel, and Environment (RCE) inventory was applied, which revealed that investigated stretches of streams fall into RCE classes III, IV and V. The concentration of Se in water at all locations was less than 1μgSeL(-1). The Se content in macrophytes differed between sampling sites, with the highest content of Se in samples from Žerovniščica stream and the lowest in samples from Lipsenjščica stream. The content of Se was the highest in moss samples (3038ngSeg(-1) DM) and in the amphibious species Veronica anagallis-aquatica (1507ngSeg(-1) DM).

Environmental assessment of freshwater ecosystems of the Sava River watershed and Cerkniško Lake, Slovenia, using the bioindicator species Fontinalis antipyretica: insights from stable isotopes and selected elements

Ten locations in the Notranjska region, Slovenia, with different land use in the catchment (town, village and agricultural areas), including reference points with different geological composition considered as unpolluted sites, were sampled for water and aquatic moss to evaluate environmental assessment in fresh water systems of the Sava River watershed. Samples of fresh water and Fontinalis antipyretica were taken in all four seasons during the years 2010 and 2012. The water chemistry of the investigated locations was dominated by , while concentrations of seasonally ranged from 2.1 to 6.4 mg L−1 and at one of the reference sites did not exceed 1.3 mg L−1. δ13CDIC values seasonally ranged from −13.3 to −8.1 ‰ and indicated waters dominated by degradation of organic matter and dissolution of carbonates. δ13Cplant values of F. antipyretica seasonally ranged from −45 to −32.9 ‰ and of δ15Nplant from −0.2 to 6.5 ‰. The higher δ15N value of 6.5 ‰ found in F. antipyretica was related to agricultural activity in the watershed. The content of minor and trace elements in F. antipyretica ranged from 4–38 µg g−1 for Ni, 17–105 µg g−1 for Zn, 2–28 µg g−1 for Pb, 0.26–1.95 µg g−1 for Cd, 4–27 µg g−1 for Cu, 4–49 µg g−1 for Cr, 1–6 µg g−1 for As and 0.33–3.24 µg g−1 for Se. The most polluted watershed was the Pšata stream (agricultural area, cattle farm with the highest concentration of nitrate in water) also with highest values for Ni, Cr, Pb, Zn and As.