Interactions between As and Se upon long exposure time and effects on nutrients translocation in golden flaxseed seedlings

Abstract

Se is a beneficial nutrient for some plant species, while As is considered a toxic element, even at low concentrations. This study investigated the interaction between As and Se on golden flaxseed (Linum usitatissimum L.) seedlings to better understand the extent of Se in the mitigation of As uptake and translocation. In addition, co-exposure experiments allowed to determine how As and Se affected absorption and distribution of the essential micronutrients Fe, Zn and Mn. Seedlings were cultivated in a 10 % v v^-1 Hoagland solution supplemented with As^V, Se^IV, Se^VI or As^V + Se^IV at different concentrations. Se^VI presented the highest toxicity and translocation factor. The toxicity of As^V was attenuated by Se^IV, which stimulated As uptake and translocation. Se^IV reduced As accumulation, establishing a tolerance mechanism. Only a high concentration of As (200 μmol L^-1) led to leaf chlorosis or seedling death, independently of co-exposure with Se species. Co-exposure also altered the uptake of Fe, Zn and Mn, without affecting As translocation from roots to shoot. In general, the interaction of As with Se was beneficial for golden flaxseed seedlings, when compared to the effects of As solely.

Keywords: Arsenic; Golden flaxseed; Hydroponic cultivation; Selenium; Translocation factor.