Selenium transport and metabolism in plants: Phytoremediation and biofortification implications

Abstract

The aim of this review is to synthesize current knowledge of selenium (Se) transport and metabolism in plants, with a focus on implications for biofortification and phytoremediation. Selenium is a necessary human micronutrient, and around a billion people worldwide may be Se deficient. This can be ameliorated by Se biofortification of staple crops. Selenium is also a potential toxin at higher concentrations, and multiple environmental disasters over the past 50 years have been caused by Se pollution from agricultural and industrial sources. Phytoremediation by plants able to take up large amounts of Se is an important tool to combat pollution issues. Both biofortification and phytoremediation applications require a thorough understanding of how Se is taken up and metabolized by plants. Selenium uptake and translocation in plants are largely accomplished via sulfur (S) transport proteins. Current understanding of these transporters is reviewed here, and transporters that may be manipulated to improve Se uptake are discussed. Plant Se metabolism also largely follows the S metabolic pathway. This pathway is reviewed here, with special focus on genes that have been, or may be manipulated to reduce the accumulation of toxic metabolites or enhance the accumulation of nontoxic metabolites. Finally, unique aspects of Se transport and metabolism in Se hyperaccumulators are reviewed. Hyperaccumulators, which can accumulate Se at up to 1000 times higher concentrations than normal plants, present interesting specialized systems of Se transport and metabolism. Selenium hyperaccumulation mechanisms and potential applications of these mechanisms to biofortification and phytoremediation are presented.

National Alliance for Water Innovation (NAWI) Agriculture Sector Technology Roadmap 2021

“…With respect to agriculture, low Se soil levels (< 1 mg/kg) are beneficial for plants, but higher levels can cause toxicity for crops. 210,211 Se is also a concern in agricultural drainage water, particularly in the Western United States. It is often present in water as an oxyanion of either Se (IV) or Se (VI).…”

Role of beneficial elements in plants: implications for the photosynthetic process

“…Selenate and selenite are the two major chemical forms of Se bioavailable in the soil. Selenate is transported in plants through sulphate transporters since both ions showed molecular similarity, while selenite is taken up by phosphate transporters (White 2018, Trippe andPilon-Smits 2021).…”

Response of common buckwheat and Tartary buckwheat from different elevations to selenium treatment

“…While selenium (Se) is known to be essential for animals, there is currently no evidence of its essentiality for plants (Hasanuzzaman et al, 2020;Trippe III and Pilon-Smits, 2021). However, it can be classified among beneficial elements.…”

“…Treating plants with Se can have a stimulating effect on their growth and development (Hasanuzzaman et al, 2020;Rady et al, 2020). It can increase their antioxidant capacity and resistance to biotic (Trippe III and Pilon-Smits, 2021) and abiotic stress such as drought (Rady et al, 2020). Selenium could be also added for the preparation, or supplemented to the diet (Germ et al, 2009).…”