HVA1-induced epigenetic reprogramming enhances abiotic stress resilience in transgenic Pelargonium graveolens

• Overexpression of HVA1 in Pelargonium graveolens enhances tolerance to osmotic and salinity stress. • Transgenic lines showed significantly improved biomass accumulation and stress resilience. • Transcriptome profiling revealed strong upregulation of chromatin remodeling genes (e.g., PgSWI/SNF, PgPHD finger). • Virus-induced gene silencing of HVA1 confirmed its regulatory role in epigenetic reprogramming. • This study identifies HVA1 as a potential epigenetic modulator for engineering climate-resilient crops. Plants adapt to environmental stresses through transcriptional reprogramming, often coordinated by chromatin-based regulatory mechanisms. In this study, we developed Pelargonium graveolens transgenic lines overexpressing the Hordeum vulgare HVA1 gene, a Group 3 LEA protein, and evaluated their performance under abiotic stress (drought and salinity stress). The transgenic lines displayed improved growth and resilience, with the most robust line HL3, showing a ∼46% increase in essential oil yield and enhanced survival under stress. Physiological analyses revealed significantly higher relative water content, proline accumulation, and chlorophyll retention, along with reduced reactive oxygen species (ROS) and lipid peroxidation in transgenic plants compared with WT controls. RNA-seq profiling indicated strong upregulation of epigenetic regulating factors, including Pgchromatin remodelling TF, SWI/SNF and PHD finger proteins, linking HVA1 expression to transcriptional reprogramming. Virus-induced gene silencing of HVA1 reversed the transcript level of the above transcript, validating its functional role. Collectively, our findings demonstrate that HVA1 overexpression promotes transcriptional activation of epigenetic regulators, offering a strategy for engineering stress-resilient aromatic crops.