International Journal of Horticulture, 2025, Vol.15, No.5, 242-256 http://hortherbpublisher.com/index.php/ijh 246 applications require rigorous evaluation of microbial stability, environmental persistence and unintended ecological effects (Mahmood et al., 2016). Taken together, the diversity of seed priming strategies highlights their considerable potential in improving abiotic stress resilience in horticultural crops, but also underscores the need for species-specific optimization, safety assessments and regulatory clarity to ensure their practical applicability under real-world agricultural conditions. 3.3 Biochemical and physiological changes induced by priming Seed priming triggers a wide range of biochemical and physiological modifications that collectively enhance the plant’s ability to tolerate abiotic stress. One of the primary effects is the activation of the antioxidant defense system, including enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), which reduce oxidative damage caused by reactive oxygen species (ROS) during stress episodes (Islam et al., 2015). Priming also improves membrane stability by increasing the synthesis of membrane-stabilizing proteins and protecting lipids from peroxidation. This is critical during desiccation and rehydration phases, and particularly beneficial in temperature and drought stress conditions (Wojtyla et al., 2016). At the osmotic level, priming induces the accumulation of compatible solutes such as proline, glycine betaine, and soluble sugars (Ashraf and Foolad, 2005). These osmoprotectants help maintain cell turgor, stabilize enzymes and proteins and reduce water loss under saline or drought conditions (Zouari et al., 2019). Moreover, priming enhances the repair of damaged nucleic acids and proteins, increases ATP production, and accelerates the expression of genes related to stress tolerance. This prepares seeds for faster germination, improved energy metabolism, and early seedling vigor (Wojtyla et al., 2016). Seed priming has also been shown to modulate hormonal balance, particularly enhancing the sensitivity to abscisic acid (ABA) and fine-tuning interactions with salicylic acid (SA), jasmonic acid (JA) and ethylene. This hormonal crosstalk is crucial for coordinating defense and growth processes during early seedling development under stress conditions (Wojtyla et al., 2016). Recent studies have identified that priming can leave epigenetic marks, such as histone modifications and DNA methylation changes, which may contribute to “stress memory” and transgenerational tolerance effects, although these mechanisms are still under active investigation in horticultural species (Liu et al., 2022). Collectively, these biochemical and molecular changes induced by seed priming result in faster germination, improved seedling establishment, and greater resilience to abiotic stressors, forming the foundation of the cross-tolerance mechanisms (Figure 1) that will be explored in the following section. Moreover, many of the biochemical and physiological changes triggered by seed priming are not stress-specific, but rather enhance the plant’s general defensive capacity. This leads to the phenomenon known as cross-tolerance, in which primed plants exhibit improved resilience not only to the target stress but also to a broad range of abiotic challenges, such as drought, salinity, and heat (Liu et al., 2022). This multifaceted response results from the activation of interconnected signaling networks and defense pathways that allow plants to cope more efficiently with complex stress environments (Wojtyla et al., 2016; Johnson and Puthur, 2021). In conclusion, seed priming initiates a cascade of biochemical and physiological events that significantly improve plant performance under abiotic stress. By enhancing early vigor, activating defense pathways, and inducing metabolic readiness, primed seeds gain a competitive advantage in challenging environments. These responses, coupled with the capacity for cross-tolerance, position seed priming as a strategic, low-cost intervention to promote resilience in horticultural crops.
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