Selenium Biofortification Differentially Affects Sulfur Metabolism and Accumulation of Phytochemicals in Two Rocket Species (Eruca Sativa Mill. and Diplotaxis Tenuifolia) Grown in Hydroponics

Abstract

Biofortification can be exploited to enrich plants in selenium (Se), an essential micronutrient for humans. Selenium as selenate was supplied to two rocket species, Eruca sativa Mill. (salad rocket) and Diplotaxis tenuifolia (wild rocket), at 0–40 μM in hydroponics and its effects on the content and profile of sulphur (S)-compounds and other phytochemicals was evaluated. D. tenuifolia accumulated more total Se and selenocysteine than E. sativa, concentrating up to ~300 mg Se kg−1 dry weight from 10–40 μM Se. To ensure a safe and adequate Se intake, 30 and 4 g fresh leaf material from E. sativa grown with 5 and 10–20 μM Se, respectively or 4 g from D. tenuifolia supplied with 5 μM Se was estimated to be optimal for consumption. Selenium supplementation at or above 10 μM differentially affected S metabolism in the two species in terms of the transcription of genes involved in S assimilation and S-compound accumulation. Also, amino acid content decreased with Se in E. sativa but increased in D. tenuifolia and the amount of phenolics was more reduced in D. tenuifolia. In conclusion, selenate application in hydroponics allowed Se enrichment of rocket. Furthermore, Se at low concentration (5 μM) did not significantly affect accumulation of phytochemicals and plant defence S-metabolites.

Selenium Biofortification Impacts the Nutritive Value, Polyphenolic Content, and Bioactive Constitution of Variable Microgreens Genotypes

“…Furthermore, our findings corroborate previous findings on plant roots' capability for selenium uptake through passive diffusion and sulfate transporters due to the chemical similarity of this element with sulfur, and then it is transferred to the shoots via xylem [16,27,28]. It is well established that selenate assimilation in plants occurs through an active transport process led by sulfate transporters (SULTRs) [27]. SULTRs mediate the sulfate movement in the vascular bundles, therefore both sulphate and selenate are actively accumulated against their electrochemical gradient in the plant cells [27,57].…”

“…Our findings were in agreement with previous works on microgreens of buckwheat [46], basil [9], and wheat [10], demonstrating the efficacy of achieving Se biofortification of microgreens. Furthermore, our findings corroborate previous findings on plant roots' capability for selenium uptake through passive diffusion and sulfate transporters due to the chemical similarity of this element with sulfur, and then it is transferred to the shoots via xylem [16,27,28]. It is well established that selenate assimilation in plants occurs through an active transport process led by sulfate transporters (SULTRs) [27].…”

“…Selenium enhances the activity of antioxidant enzymes, such as lipoxygenase, catalase, ascorbate, and glutathione peroxidase, which in turn elicit the synthesis of secondary metabolites, including carotenoids, phenols, flavonoids, and vitamins [10,25,26]. Plants assimilate Se mainly in the form of selenate or selenite, the former being transported actively by sulphate transporters [27], while the latter is taken up via phosphate transporters [28]. However, compared to selenate, selenite is less soluble, more phytotoxic, and more difficult to transport and accumulate in plant tissues; for this reason, the selenate form is preferred for biofortification [29,30].…”

“…Although many Se biofortification studies have covered a wide range of cereal and vegetable crops, including wheat [35], rice [36], tomato [37], potato [38], beans [39], pea [40], endive [41], broccoli [42], rocket [27], lettuce [43], garlic [44], and shallot [45], the biofortification of microgreens with selenium has been poorly studied, aside from a few works on buckwheat [46], wheat [10], and basil [9]. Nevertheless, the effect of Se biofortification on the phenolic profile of microgreens has never been investigated.…”

Manure Fertilization Gives High-Quality Earthworm Coprolites with Positive Effects on Plant Growth and N Metabolism

“…Oat seeds (Avena Sativa var. Goodfield) were sterilized using 0.1 M Na(ClO) [66] and sowed in pots (density = 16 seeds per pot) filled with sand and placed inside a climatic chamber with a 12 h light/12 h dark cycle, air temperature of 24/21 • C, relative humidity of 70/85%. The seeds were allowed to germinate in the pots for one week in the presence of water.…”