Iron oxide nanoparticles as effective nano-fertilizer for alleviating arsenic toxicity in barley: physiological and molecular mechanisms

Abstract

Arsenic (As) contamination in soils posed a significant threat to sustainable agriculture and food safety. The application of metal nanoparticle (MNP) technology in alleviating heavy metal toxicity is an emerging and promising field. However, little has been known about the effect of FeO-NPs in alleviating As toxicity and accumulation in plants. In this study we examined the roles of FeO-NPs in promoting barley growth and alleviating As toxicity. Exposure of plants to As stress (100 μM As) severely reduced growth and photosynthesis, and also caused disorder of other physiological traits, including enhanced oxidative stress and nutrient imbalance. Addition of FeO-NPs (20 and 100 mg L-1) into the nutrient solution containing As significantly alleviated As toxicity of the two barley genotypes, mainly reflected by better plant growth, higher photosynthetic rate, and lower AOS (active oxygen species) content. As toxicity and genotypic difference between BCS-158 (As tolerant) and BCS-016, As sensitive) are closed related to As uptake and accumulation in plant tissues, with BCS-158 having lower As concentrations in both roots and shoots than BCS-016. Addition of FeO-NPs dramatically reduced As uptake and accumulation in the plants exposed to As treatment, thus resulting in alleviation of As toxicity. The reduction of As uptake and accumulation in the plants subjected to FeO-NPs is attributed to upregulating expression of iron transporter genes (HvIRT1 and HvIRT2) and suppressing expression of arsenic transporter genes (HvLsi1 and HvLsi2). The current results show the potential of FeO-NPs application in As-contaminated soils for improving crop production and food safety, but more research should be done to evaluate its ecological risk and determine the optimal doses before they are efficiently applied in crop production.