Strontium-induced mineral imbalance, cell death, and reactive oxygen species generation in Arabidopsis thaliana

Abstract

Strontium (Sr) is a known non-essential element for plants. However, its toxic effects at high concentration on plants remain unclear. Here the effects of Sr on the growth and phytotoxicity were investigated in Arabidopsis thaliana. The plants grown on a medium containing 10-mM Sr showed reduced root fresh weight (FW) and root elongation, which suggested that high Sr concentration could inhibit root growth. Assessment of Sr in the shoots and roots indicated that its concentrations increased in a dose-dependent manner. Sr treatment caused reduced calcium (Ca) levels in a dose-dependent manner, while photosynthetic pigments were also reduced. Evans blue staining of shoots and roots treated with 10-mM Sr revealed that cell death was induced by Sr accumulation. Addition of potassium iodide (KI), a reduction compound, in Sr containing agar medium to determine the relationship between reactive oxygen species (ROS) and Sr toxicity showed that it could alleviate the Sr toxicity to growth. The 3,3'-Diaminobenzidine (DAB) detection of ROS production in the leaves and roots treated with 1- and 10-mM Sr confirmed that cell death was induced by ROS.