Stress-Responsive Retrotransposon Activation in Plants: A Genomic Survival Strategy Across Abiotic Stresses

Transposable elements (TEs), once dismissed as genomic “junk,” are now recognized as pivotal regulatory components in plant stress responses(Makarevitch et al., 2015). Among these, retrotransposons—especially long terminal repeat (LTR) elements such as the Copia and Gypsy families—exhibit remarkable transcriptional plasticity under abiotic stresses including heat, drought, salinity, cold, and ultraviolet (UV) radiation (Lisch, 2019). Recent studies have illuminated how these elements are transcriptionally reactivated under stress, reshaping the transcriptome and regulatory networks across diverse plant taxa (Kawakatsu, 2022; Makarevitch et al., 2015). Stress-induced TE activation is driven by epigenetic reprogramming, including DNA hypomethylation (Pecinka & Scheid, 2017), chromatin remodeling (Horváth et al., 2017), and the suppression of small RNA pathways such as RdDM (Ito et al., 2016). Many LTRs harbor stress-responsive cis-elements like heat shock elements (HSEs), allowing hijacking of stress transcriptional machinery (Cavrak et al., 2014; Matsunaga, 2015). For instance, the ONSEN retrotransposon is activated during heat stress in Arabidopsis (Ito et al., 2016), while Tos17 is upregulated in rice under drought conditions via microRNA modulation (Wang, 2018). Different stressors elicit both unique and convergent patterns of TE reactivation. Drought-responsive TEs exhibit heritable epigenetic changes and contribute to transcriptomic plasticity in crops such as maize, soybean, and tomato (Zeng et al. 2021; Li et al. 2019)(Li, 2019). Salinity stress triggers ABA-mediated retrotransposon activity(Benoit et al., 2019), while cold and UV stress responses reveal conserved activation patterns involving Copia-like elements across species (Bui & Grandbastien, 2016; Zeller, 2019). Far from being passive passengers, stress-responsive TEs serve as cis-regulatory rewiring agents, introduce new transcriptional start sites, and influence plant adaptation (Chuong et al., 2016; Quadrana et al., 2019). This growing body of evidence positions retrotransposons as evolutionary tools, fostering resilience and heritable variability under climate stress. Understanding and leveraging these elements opens avenues in genome engineering, TE-based biomarkers, and stress-resilient breeding strategies, redefining how plants dynamically remodel their genomes in response to environmental cues.