Algal polysaccharides–Selenium nanoparticles regulate the uptake and distribution of selenium in rice plants

Abstract

IntroductionSelenium (Se) is an essential trace element required for proper human and animal health.MethodsIn this paper, we investigated the uptake and distribution characteristics of a new Se fertilizer, which comprises algal polysaccharides–selenium nanoparticles (APS-SeNPs), in rice plants in both hydroponic and pot experiments.ResultsThe results from the hydroponic experiments revealed that the rice root uptake of APS-SeNPs fitted the Michaelis–Menten equation, with a Vmax of 13.54 μg g−1 root dry weight (DW) per hour, which was 7.69 and 2.23 times those of selenite and selenate treatments, respectively. The root uptake of APS-SeNPs was inhibited by AgNO3 (64.81%–79.09%) and carbonyl cyanide 3-chlorophenylhydrazone (CCCP; 19.83%–29.03%), indicating that the uptake of APS-SeNPs by rice roots is mainly via aquaporins and is also affected by metabolic activity. Moreover, sulfur deficiency caused rice roots to absorb more APS-SeNPs, but treatment with APS-SeNPs increased the expression of the sulfate transporter OsSULTR1;2 in the roots, suggesting that OsSULTR1;2 is probably involved in the uptake of APS-SeNPs. The application of APS-SeNPs significantly increased the Se content in rice plants and the apparent Se uptake efficiency compared with selenate and selenite treatments. Most of the Se in the roots of rice plants was distributed in the cell wall, while it was primarily located in the cytosol in the shoots when treated with APS-SeNPs. The results from the pot experiments indicated that the application of Se enhanced the Se content of each rice tissue. It is worth noting that the Se content in brown rice under APS-SeNP treatment was higher than that under selenite or selenate treatment and was mainly concentrated in the embryo end, with the Se in organic form.DiscussionOur findings provide important insights into the uptake mechanism and the distribution of APS-SeNPs in rice plants.

Selenium Nanoparticles for Antioxidant Activity and Selenium Enrichment in Plants

“…Initially, SeNPs dispersed in an aqueous solution are transported into the interior of bean sprout cells through sulfate transporters (HAST) or phosphate transporters (PHT), while a small amount of SeNPs enters the cells through osmosis. , Once inside the cells, the SeNPs are further reduced to selenide (Se 2– ) by sulfite reductase or glutathione (Glu). The Se 2– then reacts with O-acetylserine thiolytic enzymes to form selenium binding proteins (SBPs), which can be further converted by enzymes into other seleno-amino acids. ,, For instance, cysteine desulfurase enzymes can convert SBPs to selenoalanine and selenocysteine (SeCys) . It is important to note that if excessive SeNPs are used, not all of them can be converted to organic selenium.…”

“…The Se 2− then reacts with O-acetylserine thiolytic enzymes to form selenium binding proteins (SBPs), which can be further converted by enzymes into other selenoamino acids. 16,56,57 For instance, cysteine desulfurase enzymes can convert SBPs to selenoalanine and selenocysteine (SeCys). 58 It is important to note that if excessive SeNPs are used, not all of them can be converted to organic selenium.…”