Insights into Epigenetic Regulation of Systemic Acquired Resistance in Plants
ABSTRACT
Plants, as sessile organisms, depend on a multi-layered innate immune system to withstand diverse biotic stressors. Their defense begins with physical and chemical barriers, followed by inducible responses mediated through pattern-triggered (PTI) and effector-triggered immunity (ETI). These local defenses integrate with systemic mechanisms, notably Systemic Acquired Resistance (SAR) and Induced Systemic Resistance (ISR), which provide long-lasting, broad-spectrum protection. SAR operates through salicylic acid (SA)–dependent signaling involving NPR1, NPR3/4, WRKY, and TGA transcription factors, along with metabolites like N-hydroxy-pipecolic acid (NHP). Epigenetic mechanisms, including DNA methylation and histone modifications such as acetylation and methylation, fine-tune SAR by modulating chromatin accessibility and gene expression. These heritable yet reversible changes establish immune memory, strengthening both local and transgenerational resistance and offering promising strategies for durable disease management and sustainable crop protection.
KEYWORDS: Systemic acquired resistance, Gene regulation, DNA methylation, Histone modification, Salicylic acid signaling, Plant immunity
