Helium Enhances Brassica napus Cadmium Tolerance by Reducing Cadmium Uptake/Translocation and Modulating Redox Balance

Helium, a traditionally inert gas, has garnered interest in medicine, yet its role in plant heavy metal responses is still elusive. Here, we investigated whether or how helium orchestrates rapeseed cadmium (Cd) tolerance. Hydroponic experimental results demonstrated that helium-enriched solution markedly alleviated Cd-induced inhibition of root growth. Importantly, helium-inhibited Cd uptake was evidenced by non-invasive micro-test technology (NMT). By using grafting experiments, we clearly observed differential responses in Cd accumulation. Since shoot tissues had relatively lower Cd contents, the inhibited root-to-shoot Cd translocation might be used to explain the low Cd accumulation achieved by helium. Further analysis indicated that helium enhanced Cd sequestration in root cell walls. Remarkably, Cd-triggered oxidative damage was effectively eliminated via stimulating the antioxidant system. Collectively, these findings suggest that restricted Cd uptake and inhibition in translocation, as well as antioxidant capacity stimulation, might be important mechanisms for helium-orchestrated Cd tolerance, thus providing a potential approach for sustainable agriculture and food security.