Abstract

Arsenic (As) contamination in soil and water severely restricts plant productivity and threatens food safety and ecosystem health. To evaluate the potential of fungal arsenic transporters in improving plant arsenic tolerance, we functionally characterized CdACR3 from Coprinellus disseminatus using a yeast heterologous expression system and transgenic tobacco plants. Overexpression of CdACR3 in yeast markedly enhanced growth and survival under arsenate stress, confirming its role in arsenic detoxification. In tobacco, ectopic expression of CdACR3 significantly improved arsenic tolerance, as reflected by enhanced growth, elevating antioxidant enzyme activity(increased SOD, POD, CAT), lower oxidative damage (reduced MDA), and better preservation of chloroplast and mitochondrial ultrastructure. Compared with wild-type plants, transgenic lines accumulated less arsenic and showed reduced root-to-shoot translocation under arsenate exposure. Arsenic speciation analysis further demonstrated that CdACR3 promoted As(III) efflux from roots into the external medium, thereby limiting arsenic retention in plant tissues. Transcriptomic analysis revealed that CdACR3 expression mainly enriched pathways associated with phenylpropanoid biosynthesis, glutathione metabolism, and flavonoid biosynthesis, including genes related to lignin formation (NtCAD, NtCCR), glutathione metabolism (NtGST), and Flavonoid synthesis (NtHCT). Collectively, these results indicate that CdACR3 enhances plant arsenic tolerance by coordinating arsenite efflux, redox homeostasis, and cell wall reinforcement, providing new evidence for engineering crops with enhanced arsenic tolerance and reduced arsenic accumulation.