Helium-enriched solution enhances rapeseed salinity tolerance via reestablishing ion homeostasis and decreasing methylglyoxal accumulation

Helium was previously regarded as a biologically inert gas. However, whether or how this by-product of natural gas influences crop physiology remains largely unknown. Here, our hydroponic experiments showed that helium-enriched solution increases NaCl tolerance in rapeseed, as seedling root growth was less inhibited than saline solution alone. Helium addition decreased Na + to K + ratio in roots, caused by the enhanced accumulation of K + (impaired K + efflux) and reduced accumulation of Na + (increased Na + efflux), further confirmed by up-regulating sodium and potassium transporters genes. Consistently, reactive oxygen species (ROS)-mediated lipid peroxidation in roots was remarkably abolished, supported by the stimulation of ascorbate-glutathione cycle and other antioxidant enzymes. Importantly, helium could decrease methylglyoxal accumulation by stimulating glyoxalase enzyme activity. Thus, helium reestablished ion and redox homeostasis to combat NaCl stress, which opens a new window for helium-based biology. Schematic model describing that salinity tolerance is stimulated by helium. SOS1: salt overly sensitive 1; SOS2: salt overly sensitive 2; HAK5: high-affinity potassium transporter 5; ROS: reactive oxygen species; MG: methylglyoxal; H 2 O 2 : hydrogen peroxide; O 2 - : superoxide radical; CAT: catalase; POD: peroxidase; SOD: superoxide dismutase; NHX1: vacuolar membrane-sodium hydrogen exchangers 1; AsA: ascorbate; GSH: glutathione. • Helium-enriched solution stimulated salt tolerance in rapeseed seedlings. • Ion homeostasis was positively influenced by helium. • Methylglyoxal accumulation was mitigated via stimulating glyoxalase activity and transcripts.