Understanding boosting selenium accumulation in Wheat (Triticum aestivum L.) following foliar selenium application at different stages, forms, and doses

Authors: WANG, MIN - Northwest Agricultural & Forestry University; ALI, FAYAZ - Northwest Agricultural & Forestry University; WANG, MENGKE - Northwest Agricultural & Forestry University; TOAN DINH, QUANG - Northwest Agricultural & Forestry University; ZHOU, FEI - Northwest Agricultural & Forestry University; Banuelos, Gary; LIANG, DONGLI - Northwest Agricultural & Forestry University

Submitted to: Environmental Science and Pollution Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2019
Publication Date: 12/5/2019
Citation: Wang, M., Ali, F., Wang, M., Toan Dinh, Q., Zhou, F., Banuelos, G.S., Liang, D. 2019. Understanding boosting selenium accumulation in Wheat (Triticum aestivum L.) following foliar selenium application at different stages, forms, and doses. Environmental Science and Pollution Research. 27:717-728. https://doi.org/10.1007/s11356-019-06914-0.
DOI: https://doi.org/10.1007/s11356-019-06914-0

Interpretive Summary: Approximately 0.5-1 billion people are affected worldwide by low selenium (Se) intake. Consumption of food crops is the major source of bioavailable Se for most people. Consequently, practical strategies need to be developed to produce crops with higher Se concentrations. To address this need, we evaluated the agronomic strategy called biofortification to produce Se-enriched wheat by foliar-application of Se at different growth stages of field-grown wheat. We determined that foliar application of Se as either selenite and especially selenate at pre-filling stage, effectively increased the Se concentration of wheat grains. In addition, we importantly detected organic Se as the major form of Se detected in grains for both forms of Se applied. Our results demonstrated that Se biofortification of wheat was most effectively and safely produced with the foliar application of selenate at the rate of 20 g/ha at pre-filling stage. Most important, we detected that organic Se was the major form of Se detected in the grain with both forms of Se foliarly applied. Our findings are useful for developing effective Se biofortification strategies for a worldwide-consumed crop like wheat. Importantly, this strategy produced Se-enriched wheat products containing organic Se, which is a highly bioavailable form of Se for biological systems. This biofortification strategy for wheat will be important for those in susceptible Se deficient regions trying to safely improve Se status via Se-enriched crops.

Technical Abstract: Others have reported that approximately 0.5-1 billion people worldwide are affected by low selenium (Se) intake. This observation is alarming in humans since Se is an essential component of antioxidant enzymes such as glutathione peroxidase (GSH-Px) and thioredoxin reductase (TPx). Moreover, the deficiency of Se has been linked with the occurrence of Kaschin-Beck disease, Keshan disease, and cardiovascular and lung diseases (asthma and chronic lung disease). To increase Se intake in humans, producing Se-enriched food crops from widely-consumed crops like rice and wheat produced via Se biofortification strategies has been newly recognized as an optimal choice for Se supplementation in many Se-deficient populations. Numerous studies have shown that foliar application of Se has successfully promoted the Se content in various plant species. Among Se-enriched crops, wheat (Triticum aestivum L.) is a main staple food for more than one third of the world’s population and its derivative products such as bread, cake, cereal, and pasta are also essential components in people’s diets. To explore the distribution and translocation of exogenous Se foliar-applied to wheat, a field experiment was performed to evaluate the foliar application of different forms of Se (selenite and selenate) applied at different rates (20 g/ha and 100 g/ha) at different growth stages (pre-flowering and pre-filling stage) on Se content and Se distribution in different parts of 7-month old wheat plants. One month after foliar application of selenate and selenite, respectively, plants were harvested and analyzed for total Se and Se species in grains and other parts of the plant. The Se concentration in wheat grain was significantly (p<0.05) increased with both forms and rates of Se applied either at pre-flowering or pre-filling stages. The safe and ideal Se concentration of 1.6 ug/g in the grains was determined in the plants treated with 20 g/ha selenate at pre-filling stage. The main Se species detected in wheat grain was selenomethionine (SeMet) for all foliar applications, accounting for about 67%-86% of total Se. Results of this study demonstrated that the foliar application of selenate at 20 g/ha at pre-filling stage was the safest and most efficient strategy for Se biofortification in wheat. Consumption of Se-enriched wheat or wheat products may be effective for increasing Se intake in Se-deficient populations throughout the world. Additional research is currently in progress on evaluating the impact of "processing" on Se content and quality of wheat products.