Developing drought-tolerant almond cultivars is essential for sustainable production in water- limited regions. This study investigated the phenotypic, physiological, morphological, and preliminary transcriptional responses of five cultivars (Texas, Filippo Ceo, Makako, Ferragnes, and Tuono) subjected to three controlled irrigation regimes: full irrigation (CTRL), static stress (SS), and dynamic stress (DS). The SS treatment maintained 45% Available Water Content (AWC), while in DS the AWC declined progressively to 15% before rehydration. A comprehensive set of growth and physiological traits was assessed, including plant height, shoot diameter, leaf area, biomass, stomatal conductance (gs), transpiration, relative water content, electron transport rate exiting from PSII, leaf–air temperature difference (ΔT), and the carboxylation index (PKO/KC). In addition, RGB imaging was used to quantify morphological and colorimetric traits. Projected shoot area and top-view area emerged as the most effective RGB-derived variables for distinguishing treatment effects within each variety. Among physiological traits, gs, ΔT and PKO/KC were the most sensitive indicators of drought response, showing a significant correlation each other. This highlights the potential of integrating thermal imaging and gas-exchange measurements for efficient drought phenotyping. The DS treatment produced the clearest cultivar differentiation. Texas and Filippo Ceo maintained moderate thermoregulation and higher stomatal functionality under low water availability (30% AWC), whereas Ferragnes, Makako, and Tuono displayed marked reductions in gs and carboxylation efficiency. Preliminary transcriptomic data revealed that SS induced significant changes in gene expression, particularly in genes associated with ABA signalling and heat shock proteins, while DS triggered minimal transcriptional responses until AWC declined below approximately 60%. Expression patterns were highly stress- and cultivar-specific. Overall, cultivars exhibited contrasting drought-response strategies, prioritizing either growth maintenance or leaf- level functional stability. Texas consistently showed the highest drought tolerance, while Makako appeared the most susceptible. These findings, provide valuable tools for breeding, selection and irrigation management.
Integrated Morphological, Physiological, and Transcriptional Profiling Reveals Contrasting Drought-Response Strategies in Almond Cultivars
Leonardo Conti;Giuseppe Di Leo;Gaetano Giudice;Vito Ugenti;Antonella Simini;Stefano Pavan;Pasquale Losciale
2026-01-01
Abstract
Developing drought-tolerant almond cultivars is essential for sustainable production in water- limited regions. This study investigated the phenotypic, physiological, morphological, and preliminary transcriptional responses of five cultivars (Texas, Filippo Ceo, Makako, Ferragnes, and Tuono) subjected to three controlled irrigation regimes: full irrigation (CTRL), static stress (SS), and dynamic stress (DS). The SS treatment maintained 45% Available Water Content (AWC), while in DS the AWC declined progressively to 15% before rehydration. A comprehensive set of growth and physiological traits was assessed, including plant height, shoot diameter, leaf area, biomass, stomatal conductance (gs), transpiration, relative water content, electron transport rate exiting from PSII, leaf–air temperature difference (ΔT), and the carboxylation index (PKO/KC). In addition, RGB imaging was used to quantify morphological and colorimetric traits. Projected shoot area and top-view area emerged as the most effective RGB-derived variables for distinguishing treatment effects within each variety. Among physiological traits, gs, ΔT and PKO/KC were the most sensitive indicators of drought response, showing a significant correlation each other. This highlights the potential of integrating thermal imaging and gas-exchange measurements for efficient drought phenotyping. The DS treatment produced the clearest cultivar differentiation. Texas and Filippo Ceo maintained moderate thermoregulation and higher stomatal functionality under low water availability (30% AWC), whereas Ferragnes, Makako, and Tuono displayed marked reductions in gs and carboxylation efficiency. Preliminary transcriptomic data revealed that SS induced significant changes in gene expression, particularly in genes associated with ABA signalling and heat shock proteins, while DS triggered minimal transcriptional responses until AWC declined below approximately 60%. Expression patterns were highly stress- and cultivar-specific. Overall, cultivars exhibited contrasting drought-response strategies, prioritizing either growth maintenance or leaf- level functional stability. Texas consistently showed the highest drought tolerance, while Makako appeared the most susceptible. These findings, provide valuable tools for breeding, selection and irrigation management.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
