Variation in selenium tolerance and accumulation among 19 Arabidopsis thaliana accessions

Selenium (Se) is an essential element for many organisms but also toxic at higher levels. The objective of this study was to identify accessions from the model species Arabidopsis thaliana that differ in Se tolerance and accumulation. Nineteen Arabidopsis accessions were grown from seed on agar medium with or without selenate (50 μM) or selenite (20 μM), followed by analysis of Se tolerance and accumulation. Tissue sulfur levels were also compared. The Se Tolerance Index (root length+Se/root length control) varied among the accessions from 0.11 to 0.44 for selenite and from 0.05 to 0.24 for selenate. When treated with selenite, the accessions differed by two-fold in shoot Se concentration (up to 250 mg kg−1) and three-fold in root Se concentration (up to 1000 mg kg−1). Selenium accumulation from selenate varied 1.7-fold in shoot (up to 1000 mg kg−1) and two-fold in root (up to 650 mg kg−1). Across all accessions, a strong correlation was observed between Se and S concentration in both shoot and root under selenate treatment, and in roots of selenite-treated plants. Shoot Se accumulation from selenate and selenite were also correlated. There was no correlation between Se tolerance and accumulation, either for selenate or selenite. The F1 offspring from a cross between the extreme selenate-sensitive Dijon G and the extreme selenate-tolerant Estland accessions showed intermediate selenate tolerance. In contrast, the F1 offspring from a cross between selenite-sensitive and -tolerant accessions (Dijon G×Col-PRL) were selenite tolerant. The results from this study give new insight into the mechanisms of plant selenium (Se) tolerance and accumulation, which may help develop better plants for selenium phytoremediation or as fortified foods.