Selenium biofortification of broccoli and carrots grown in soil amended with Se-enriched hyperaccumulator Stanleya pinnata

Authors: Banuelos, Gary; Arroyo, Irvin; PICKERING, I - University Of Saskatchewan; YANG, S - University Of Saskatchewan; FREEMAN, J - National Aeronautics And Space Administration (NASA)

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2014
Publication Date: 2/1/2015
Citation: Banuelos, G.S., Arroyo, I.S., Pickering, I.J., Yang, S.I., Freeman, J.L. 2015. Selenium biofortification of broccoli and carrots grown in soil amended with Se-enriched hyperaccumulator Stanleya pinnata. Food Chemistry. 166:603-608.

Interpretive Summary: Producing selenium (Se)-enriched crops is viewed as nutritionally significant for Se-deficient regions of the world such as China, UK, Europe, Australia, and New Zealand, where diets are reported to have insufficient amounts of Se, due in part to inadequate Se in food crops grown in low Se-containing soils. In contrast to Se-deficient regions, there are also areas with excessive Se, i.e., western side of California’s Central Valley, which contain high levels of natural-occurring inorganic-Se. To mitigate the movement and impact that Se may exert on ecosystems in this region, a plant-based agronomic strategy called “phytomanagement” was developed for removing soluble forms of inorganic-Se by selective plant species. In this regard, unique plants known as ‘Se hyperaccumulators’, are of interest for the phytomanagement of Se because they can hyper-accumulate Se within their leaf tissues. To sustain a long-term, cost effective Se phytomanagement program it is imperative to find alternative ways to utilize the harvested Se-enriched shoot biomass. In this study, we investigated the application of Se-enriched hyperaccumulator Prince’s Plume grown on Se-rich soils as a Se-enriched organic amendment to soils for producing Se-enriched broccoli and carrots. We successfully demonstrated that Se-enriched Prince’s Plume can be used as an organic Se fertilizer for increasing Se content in broccoli and carrots under field conditions. We characterized total-Se accumulation and the extractable forms of Se present in broccoli and carrots grown in these amended soils. Future studies may consider investigating for any nutritional effects of utilizing these Se-enriched food crops in the diets of biological systems with both normal and low Se status.

Technical Abstract: Amending soils with Se-hyperaccumulator plant derived sources of selenium (Se) may be useful for increasing Se content in food crops in Se-deficient regions of the world. In this study, we evaluated total Se and the different chemical species of Se in broccoli and carrots grown in soils amended with Se-enriched ground shoots (~700 ug/g) of the Se-hyperaccumulator Stanleya pinnata (Prince’s Plume). With increasing application rates of S. pinnata, total plant Se concentrations increased to higher levels ranging from 0.5 to 3.5 ug/g in broccoli florets and ranging from 0.3 to 2.3 ug/g in carrots. Selenium compounds in aqueous extracts were analyzed by SAX-HPLC-ICPMS and identified as a variety of mainly organic-Se forms, which included: selenomethionone, selenocystine, methylselenocysteine, selenate, and selenite. Together with bulk Se K-edge X-ray absorption near-edge structure (XANES) analysis performed on broccoli florets and carrot root, we demonstrated that Se-enriched S. pinnata can be used as a soil amendment for enriching broccoli and carrots with different forms of organic-Se. These results may be of more significance in Se-deficient regions around the world where inorganic sources of Se are already used for producing crops with higher levels of Se.