Molecular Mechanisms of Silicon-Mediated Alleviation of Arsenic Induced Oxidative Stress in Rice Plants.

Arsenic (As) uptake by rice poses a double threat to food security by directly impacting human health through consumption of As-tainted grains and by decreasing rice yield. Arsenic causes numerous physiological changes in higher plants including oxidative stress. Silicon, an important nutrient for the optimal growth and sustainable production of rice (Oryza sativa L.), can alleviate the abiotic stresses caused by arsenic. However, the molecular mechanisms of the effect of silicon addition on alleviating arsenic-induced oxidative stress have not been elucidated. Here, hydroponic experiments were conducted to investigate the impacts of silicon addition on arsenic-induced oxidative stress in rice (Oryza sativa L.) cultivar M206 exposed to 6.7 μM arsenite by adding low (50 μM) or high silicon (1500 μM) as silicic acid. The addition of high silicon can significantly decrease arsenic accumulation in the roots and shoots. We use confocal microscopy to observe the effect of silicon on alleviation of arsenic-induced oxidative stress in rice. The ornithine d-aminotransferase gene (OsOAT) responsible for oxidative stress was observed to be overexpressed under arsenic exposure by using real-time reverse transcription quantitative PCR. However, the addition of high silicon to arsenite-treated rice plants did not change the expression of OsOAT compared to the control. The current results demonstrated that silicon addition may alleviate arsenic-induced oxidative stress in rice through regulating the genes related to oxidative stress.