Biometric and molecular responses to water deficit in two contrasting Italian durum wheat cultivars

The impact of global warming on agriculture is widely recognized, and events of water scarcity are predicted to increase in the upcoming years. In our study, we examined the response of two Triticum turgidum spp. durum cultivars, Marco Aurelio (MA) and Antalis (AN), to water deficit stress, focusing on biometric traits and the expression of selected genes in their shoots and roots. During the first part of the water stress cycle that lasted 25 days, MA and AN reached soil water content (SWC) of 14 and 25%, respectively. The applied water stress had a significant impact on plant growth, adversely affecting several biometric traits. Notably, the two cultivars showed distinct responses to drought: AN maintained root biomass, whereas MA sustained similar shoot biomass through spike production. Despite these differences, total plant biomass of the two genotypes did not differ under water stress conditions, suggesting an improved water use efficiency in AN. Gene expression analyses indicated a broadly similar stress response in both cultivars, marked by the activation of genes involved in stress response, hormone metabolism and detoxification pathways. However, two genes associated with flowering regulation, IAA15 and NTL3A, were specifically up-regulated in the shoots of MA plants under stress, enabling these plants to flower under stress conditions. The study examined how two durum wheat cultivars respond to water deficit at both the phenotypic and gene expression levels. While both cultivars showed similar reductions in biomass, they differed in water use and flowering time under stress, traits that could be useful for improving yield in dry climates. Early flowering response, particularly in the Antalis cultivar, led to improved water use efficiency (WUE) and may help avoid stress during the reproductive stage, potentially boosting yields.