Synergistic regulation of cadmium tolerance by a 2 C protein phosphatase and nano molybdenum by modulating cellular structure, metal transport, and redox homeostasis in polyploid rice.

Abstract

Cadmium (Cd) contamination in rice systems poses a significant risk to food safety and human health, necessitating the identification of key genetic regulators and develop effective mitigation strategies. In this study, the role of the protein phosphatase 2 C gene NY1 in Cd tolerance was investigated using a CRISPR/Cas9-derived ny1 mutant in neo-tetraploid rice, and the potential of molybdenum oxide nanoparticles (MoO₃-NPs) to alleviate Cd toxicity was evaluated. Under Cd stress, loss of NY1 function significantly increased plant sensitivity, as evidenced by greater reductions in growth and photosynthetic pigments, higher Cd accumulation, and increased oxidative damage compared to the wild type. The ny1 mutant exhibited disrupted redox homeostasis, characterized by higher levels of H2O2 and malondialdehyde and reduced activities of key antioxidant enzymes. Cytological analyses revealed severe damage to root cell cellular architecture and xylem structure in ny1 under Cd exposure. Transcriptome profiling further demonstrated that NY1 regulates Cd tolerance by coordinating genes involved in metal uptake and transport, oxidative stress responses, cytoskeletal organization, and DNA replication and repair. Genes linked to Cd sequestration and detoxification were downregulated in ny1, whereas uptake-related transporters were upregulated, contributing to increased Cd accumulation. Application of MoO3-NPs partially mitigated Cd toxicity in both genotypes by reducing Cd uptake, enhancing antioxidant capacity, and improving physiological performance, although the mutant remained more sensitive than the wild type. The results indicate that NY1 is vital in enhancing Cd tolerance in tetraploid rice by regulating metal transport and redox homeostasis. They also highlight MoO₃-NPs as a promising supplementary strategy for reducing Cd accumulation in rice ecosystems. These findings provide valuable insight into the potential application of nanomaterials for mitigating Cd contamination in rice cultivation. Nevertheless, further research is required to evaluate their long-term efficacy, environmental safety, and practical applicability under field conditions.