Uptake Dynamics of Ionic and Elemental Selenium Forms and Their Metabolism in Multiple-Harvested Alfalfa (Medicago sativa L.)

Abstract

A pot experiment, under greenhouse conditions, was carried out aiming at investigating the agronomic biofortification of alfalfa (Medicago sativa L.) with Se and monitoring the Se uptake and accumulation dynamics within four consecutive harvests within the same growing season. Two ionic Se forms, i.e., sodium selenate (Se (VI)) and sodium selenite (Se (IV)), were applied once at a rate of 1, 10, and 50 mg kg−1 (added on Se basis), while 10 and 50 mg L−1 of a red elemental Se (red Se0) were used; all Se treatments were added as soil application. Application of Se (VI) at the rate of 50 mg kg−1 was toxic to alfalfa plants. The effect of Se forms on Se accumulation in alfalfa tissues, regardless of the applied Se concentration, follows: Se (VI) > Se (IV) > red Se0. The leaf, in general, possessed higher total Se content than the stem in all the treatments. The accumulation of Se in stem and leaf tissues showed a gradual decline between the harvests, especially for plants treated with either Se (VI) or Se (IV); however, the chemically synthesized red Se0 showed different results. The treatment of 10 mg kg−1 Se (VI) resulted in the highest total Se content in stem (202.5 and 98.0 µg g−1) and leaf (643.4 and 284.5 µg g−1) in the 1st and 2nd harvests, respectively. Similar tendency is reported for the Se (IV)-treated plants. Otherwise, the application of red Se0 resulted in a lower Se uptake; however, less fluctuation in total Se content between the four harvests was noticed compared to the ionic Se forms. The Se forms in stem and leaf of alfalfa extracted by water and subsequently by protease XIV enzyme were measured by strong anion exchange (SAX) HPLC-ICP-MS. The major Se forms in our samples were selenomethionine (SeMet) and Se (VI), while neither selenocysteine (SeCys) nor Se (IV) was detected. In water extract, however, Se (VI) was the major Se form, while SeMet was the predominant form in the enzyme extract. Yet, Se (VI) and SeMet contents declined within the harvests, except in stem of plants treated with 50 mg L−1 red Se0. The highest stem or leaf SeMet yield %, in all harvests, corresponded to the treatment of 50 mg L−1 red Se0. For instance, 63.6% (in stem) and 38.0% (in leaf) were calculated for SeMet yield % in the 4th harvest of plants treated with 50 mg L−1 red Se0. Our results provide information about uptake and accumulation dynamics of different ionic Se forms in case of multiple-harvested alfalfa, which, besides being a good model plant, is an important target plant species in green biorefining.

Effect of Nano-Selenium on Nutritional Quality of Cowpea and Response of ABCC Transporter Family

“…After applying exogenous Se (SeNPs or Na 2 SeO 3 ), the absorption and accumulation of total Se in cowpea pods showed a dose-response relationship. The results were consistent with the research results on other leguminous plants such as Pisum sativum , Astragalus sinicus and Medicago sativa [ 35 , 36 , 37 ]. The results showed that foliar spraying of 37.5–750.0 mg/L Na 2 SeO 3 could effectively increase the contents of macromolecular bound Se and total Se in pea seedlings, which were 8.75–38.75 times and 6.01–55.65 times higher than those in the control, respectively [ 38 ].…”

Comparative growth, biochemical and sensory analyses reveal the feasibility of large-scale development of selenium-enriched Tartary buckwheat sprouts

“…The crude fat content exhibited no significant differences. Previous studies have found that exogenous selenium influences the protein content or distribution in plants (Kovács et al, 2021). Although selenium is not considered an essential trace element for plants, numerous authors have confirmed its beneficial effect on plant life (Gupta & Gupta, 2017;Malagoli et al, 2015).…”

Transcriptome analysis revealed accumulation‐assimilation of selenium and physio‐biochemical changes in alfalfa (Medicago sativa L.) leaves

“…5 Alfalfa being a good model plant has a bright future of Se enrichment in green biorefining. 6 The process of Se enrichment in plants is affected by ways of Se application, the forms of Se, and the contents of Se application. 7 Different forms of exogenous Se can be selected according to different parts of Se biofortification plants.…”

“…Furthermore, in the Se fortification of alfalfa, the addition of Se promoted the yield and increased the Se content to 40 mg kg −1 5 . Alfalfa being a good model plant has a bright future of Se enrichment in green biorefining 6 …”

“…24 Currently, the tetraploid genome of Medicago sativa has been analyzed, which is helpful for sequence splicing and functional annotation at the sequencing level. 25 Currently, there are scarce and relatively preliminary studies on Se enrichment of alfalfa, mainly in the uptake dynamics of Se in multiple-harvested alfalfa, 6 the impact of Se on quality and yield, 26 and the effect of animal husbandry after feeding Seenriched alfalfa. 27 In the present study, alfalfa samples with similar size were harvested separately before the Se treatment (denoted as 0 h) and in the 12th and 48th hour after the Se treatment.…”