Selenium preserves cytosolic-Ca²⁺ homeostasis in olive callus cells during oxidative stress

Selenium (Se) is not essential for plant nutrition, however, growing evidence suggests a role of this element against oxidative stress. Here, we investigated the antioxidant effect of Se in an experimental system consisting of suspensions of olive callus cells exposed to hydrogen peroxide. Due to the disruptive capacity of oxidative stress on cytosolic Ca2+ homeostasis, Se treatments were simply and effectively assessed with cytosolic Ca2+ measurements. Se did not alter cell morphology, nor interfered with fluorometric determinations, suggesting a suitable model for monitoring alterations of cytosolic Ca2+. Furthermore, we used thapsigargin (TG), a known inhibitor of the Ca2+-ATPases of the endoplasmic reticulum, to establish whether Se had a specific impact on oxidative stress. We found that Se antagonized H2O2-mediated perturbations of cytosolic Ca2+, but was unable to offset TG-mediated disruptions. We conclude that Se merits consideration in strategies designed to tackle abiotic stress leading to oxidative insults. Key MessageSe preserves cytosolic-Ca2+ levels from the disruptive effect of oxidative stress induced by hydrogenperoxide in olive callus cells.