Physiological Responses and Gene Expression Profiling of Drought Tolerance in Two Almond Tree Genotypes

Climate change increases drought events, resulting in lower agricultural productivity. Almond trees (Prunus dulcis (Mill.) D.A. Webb) are drought-tolerant; however, prolonged periods of water deficit can affect plant growth and productivity. The physiological and molecular responses of two almond genotypes, Filippo Ceo and Tuono, growing in the Apulia region (Italy) under well-watered and drought conditions were evaluated. Results indicate that cv. Filippo Ceo is more drought-tolerant than cv. Tuono, exhibiting higher RWC values, good levels of photosynthetic pigments, and high proline accumulation. This behavior is confirmed by gene expression analysis, which revealed upregulation of drought-responsive genes, indicating a more effective adaptation to stress of cv. Filippo Ceo. In contrast, cv. Tuono experienced greater oxidative damage and diminished physiological response. These findings indicate that cv. Filippo Ceo could be a promising cultivar for drought-prone areas, with implications for targeted breeding and agronomic strategies to improve almond tree production under water-stressed conditions.