Preliminary Study of the Genetic Response of Grapevine Buds to a Preventive Natural Polysaccharide-Based Biogel Under Simulated Late Frost Conditions

Late spring frosts represent a major threat to grapevine (Vitis vinifera L.), a risk increasingly exacerbated by climate change-driven shifts in phenology. To explore sustainable strategies for frost mitigation, this study investigated the effect of a natural polysaccharide-based biogel, derived from carob (Ceratonia siliqua L.), on the molecular response of grapevine buds exposed to severe cold stress. To this aim, a preliminary RNA-Seq analysis was carried out to compare the transcriptomes of biogel-treated frozen buds (BIOGEL), untreated frozen buds (NTF), and unstressed controls (TNT). The transcriptomic analysis revealed extensive reprogramming of gene expression under freezing stress, highlighting the involvement of pathways related to membrane stabilization, osmotic adjustment, and metabolic regulation. Interestingly, the biogel treatment appeared to attenuate the modulation of several cold-responsive genes, particularly those associated with membrane functionality. Based on these preliminary transcriptomic data, twelve candidate genes, representative of the functional classes affected by biogel treatment, were selected for qRT-PCR validation. The expression patterns confirmed the RNA-Seq trends, further suggesting that biogel application might mitigate the typical transcriptional activation induced by frost, while supporting genes involved in cellular protection and integrity maintenance. The overall analyses suggest that the biogel may act through a dual mechanism: (i) providing a physical barrier that reduces cold-induced cellular damage and stress perception, and (ii) promoting a selective adjustment of gene expression that restrains excessive defense activation while enhancing membrane stability. Although further field validation is required, this natural and biodegradable formulation represents a promising and sustainable tool for mitigating late frost injuries in viticulture.