The Nitro-Oxidative Response Is Induced in the Leaves of Barley Plants Exposed to Barium.

Barium (Ba) is classified as a non-essential element, meaning that it does not play a requisite role in the physiological processes of living organisms, but it poses a significant health risk to them. Plants that grow in Ba-rich soils, particularly near barite outcrops or mining waste, often accumulate high levels of Ba. Excess Ba in plant cells can lead to the overproduction of reactive oxygen species (ROS), which contributes to oxidative stress. Typically, nitric oxide (NO) can help alleviate heavy metal stress; however, under certain conditions, elevated levels of superoxide and nitric oxide may result in nitrosative and nitrative stress. This study investigated whether exposing barley plants to barium acetate (300 μM and 600 μM) triggers a nitro-oxidative response in spring barley plants. The molecular and biochemical analyses revealed fluctuations in the gene expression and activity of antioxidant enzymes and a steady rise in hydrogen peroxide (HO) in the leaves. Lower Ba concentrations and shorter exposures increased NO levels, while higher concentrations and more prolonged exposure reduced them, affecting nitrogen metabolism. These findings highlight the toxicological risks posed by Ba, especially for cultivated plants, and underscore the need for further research on its impact on plant physiology and the potential risks to human health.