Characterization of Selenium Accumulation, Localization and Speciation in Buckwheat-Implications for Biofortification

Area of Science:

• Agricultural Science
• Plant Physiology
• Environmental Chemistry

Background:

• Buckwheat is a vital crop in selenium-deficient regions.
• Understanding selenium (Se) metabolism in buckwheat is crucial for biofortification strategies.

Purpose of the Study:

• To investigate Se uptake, translocation, accumulation, and speciation in common and tartary buckwheat.
• To compare the effects of different selenium forms (selenate, selenite, methyl-selenocysteine) on buckwheat.
• To assess the influence of competing ions (sulfate, phosphate) on Se metabolism.

Main Methods:

• Controlled experiments supplying buckwheat with varying concentrations and forms of Se.
• Analysis of plant growth, Se content in tissues (seeds, leaves, stems), and Se localization using X-ray microprobe.
• Short-term and long-term Se uptake studies, including investigations with sulfate and phosphate.

Main Results:

• Both buckwheat species accumulated 15-40 mg Se kg⁻¹ DW in seeds, leaves, and stems from all tested Se forms.
• Methyl-selenocysteine (from plant extract) resulted in higher Se uptake and shoot accumulation compared to selenite or selenate.
• Buckwheat exhibited resistance to selenite (up to 50 μM) and tartary buckwheat to selenate (up to 75 μM); selenate also enhanced S and P accumulation.

Conclusions:

• Buckwheat effectively accumulates organic selenium, particularly when supplied as methyl-selenocysteine.
• Se speciation in seeds indicates organic C-Se-C forms, resembling selenomethionine and related compounds.
• Findings support the potential of buckwheat for selenium biofortification, with species-specific responses to different Se forms and ions.