Nano-Fe₃O₄: Enhancing the tolerance of Elymus nutans to Cd stress through regulating programmed cell death

Cadmium (Cd) poses a significant threat to plant growth and the environment. Nano-Fe₃O₄ is effective in alleviating Cd stress in plants. Elymus nutans Griseb. is an important fodder crop on the Qinghai-Tibetan Plateau (QTP). However, the potential mechanism by which nano-Fe₃O₄ alleviates Cd stress in E. nutans is not well understood. E. nutans were subjected to single Cd, single nano-Fe₃O₄, and co-treatment with nano-Fe₃O₄ and Cd, and the effects on morphology, Cd uptake, antioxidant enzyme activity, reactive oxygen species (ROS) levels and programmed cell death (PCD) were studied to clarify the regulatory mechanism of nano-Fe₃O₄. The results showed that Cd stress significantly decreased the germination percentage and biomass of E. nutans. The photosynthetic pigment content decreased significantly under Cd stress. Cd stress also caused oxidative stress and lipid peroxidation, accumulation of excessive ROS, resulting in PCD, but the effect of nano-Fe₃O₄ was different. Seed germination, seedling growth, and physiological processes were analyzed to elucidate the regulatory role of nano-Fe₃O₄ nanoparticles in promoting photosynthesis, reducing Cd accumulation, scavenging ROS, and regulating PCD, to promote seed germination and seedling growth in E. nutans. This report provides a scientific basis for improving the tolerance of Elymus to Cd stress by using nano-Fe₃O₄.