Biopriming-Induced Transcriptomic Memory Enhances Cadmium Tolerance in the Cd Hyperaccumulator Silene sendtneri

Seed biopriming is increasingly recognized as a strategy capable of inducing molecular memory that enhances plant performance under heavy-metal stress. Here, we investigated how biopriming <i>Silene sendtneri</i> seeds with <i>Paraburkholderia phytofirmans</i> PsJN establishes a transcriptional state that predisposes seedlings for improved cadmium (Cd) tolerance. RNA-seq profiling revealed that primed seeds exhibited differential gene expression prior to Cd exposure, with strong upregulation of detoxification enzymes, antioxidant machinery, metal transporters, photosynthetic stabilizers, and osmoprotectant biosynthetic genes. Enrichment of gene ontology categories related to metal ion detoxification, redox homeostasis, phenylpropanoid metabolism, and cell wall organization indicated that biopriming imprints a preparatory transcriptional signature resembling early stress responses. Upon Cd exposure, primed plants displayed enhanced physiological performance, including preserved integrity, elevated antioxidant activity, particularly peroxidases in roots, higher osmolyte accumulation, stabilized micronutrient levels, and substantially increased Cd uptake and sequestration. These coordinated responses demonstrate that biopriming induces a sustained molecular memory that accelerates and strengthens downstream defense activation. These findings demonstrate that PGPR-based biopriming establishes a stable transcriptomic memory in seeds that enhances cadmium tolerance, metal sequestration, and stress resilience, highlighting its potential for improving hyperaccumulator performance in phytoremediation and stress adaptation strategies.