Primed acclimation of two Greek olive cultivars to water deficit

Abstract Water scarcity, intensified by climate change, threatens olive cultivation in the Mediterranean region. Understanding cultivar responses to drought is key to developing strategies to sustain this vital crop. Ιn the present work, we studied the responses of two Greek olive cultivars, "Lefkolia Serron" and "Chondrolia Chalkidikis", to water limitation and we evaluated their ability to acclimatize through cis long term-priming, using a combination of morpho-physiological parameters, primary metabolite profiling and gene expression analysis of drought-related genes. Our findings indicated that the two cultivars follow different strategies to cope with water shortage and priming. Particularly, "Lefkolia Serron" showed a more conservative response, maintaining greater photosynthetic functionality, intrinsic Water Use Efficiency (iWUE) and antioxidant activity upon stress re-exposure. "Chondrolia Chalkidikis" showed greater susceptibility to stress with more pronounced changes at the morpho-physiological, metabolic and gene expression levels. Metabolomic data demonstrated shifts in energy metabolism in response to the drought cycles, while principal component analysis of gene expression patterns showed that drought priming can regulate transcriptional processes, such that drought priming aligned primed plants with controls. Pre-exposure to drought induces a form of transcriptional memory, making the plant more efficient in responding to repeated stress. These findings suggest that long-term drought priming may function as a coping strategy for stressful environmental conditions, however, it is genotype-dependent, as the outcomes vary with genetic background. Understanding olive stress responses and applying eco-friendly strategies like drought priming is a sustainable way to protect this crop from environmental threats.