Abstract
Heavy metal pollution, as a consequence of rapid industrialization and urbanization, poses a threat to highland barley grown in Tibet. This study investigates the effect of different doses of gamma irradiation (50–300 Gy) on the physio-biochemical and molecular mechanism of highland barley under heavy metal stress. Growth data showed that 50-Gy gamma irradiation had the maximal beneficial effects on the highland barley seedlings under lead/cadmium stress. The results of oxidative parameters demonstrated that 50-Gy gamma-irradiated seedlings had lower hydrogen peroxide and malondialdehyde contents under lead/cadmium stress compared to non-irradiated seedlings. Moreover, the activities of antioxidant enzyme and proline levels in 50-Gy gamma-irradiated seedlings were drastically higher than those in non-irradiated seedlings under lead/cadmium stress. Additionally, transmission electron microscopy results revealed that the 50-Gy gamma-irradiated seedlings exhibited improved chloroplasts ultrastructure compared with non-irradiated seedlings exposed to lead/cadmium stress. Notably, transcriptional expression analysis showed that 50-Gy gamma irradiation could significantly affect the expression of genes related to heavy metal transport and abscisic acid metabolism under lead/cadmium stress. Collectively, these results provide insights into the physio-biochemical and molecular mechanisms of low-dose-gamma-irradiation-enhanced heavy metal tolerance in highland barley seedlings, thus proposing gamma irradiation as a potential technology to mitigate heavy metal toxicity in crops.
Highlights
Heavy metal pollution is emerging as a serious environmental and health issue
The H2O2, MDA and proline contents as well as superoxide dismutase (SOD), POD and CAT activities of highland barley seedlings were measured by a rapid scanning ultraviolet-visible spectrometer
Chloroplast ultra-structure was detected by transmission electron microscopy (TEM) and gene expression was analyzed by real-time RT-PCR
Summary
Heavy metal pollution is emerging as a serious environmental and health issue. Heavy metals accumulating in crops are transferred to the human food chain, causing a serious threat to human health, reduction in food and feed quality as well as economic losses[1,2,3,4,5]. To understand the role of gamma irradiation in alleviating Pb/Cd-induced oxidative stress, the activities of several representative antioxidant enzymes (SOD, CAT and POD) in highland barley seedlings after different treatments were investigated.
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