Water scarcity can negatively affect crop yield, posing a significant threat to global food security, such as drought. Plant growth-promoting rhizobacteria (PGPR), either as single strains or synthetic communities (SynComs), has shown promise in alleviating drought stress in various plant species. In this study, we examined the effects of water limitation on Salvia officinalis and the potential of a SynCom composed of five phosphate-solubilizing, auxin-producing, and/or nitrogen-fixing Gram-negative bacteria to enhance plant growth and drought tolerance. Plant growth, morphology, physiology, and leaf metabolomic profiles were assessed using a combination of physiological measurements and LC-MS untargeted metabolomics. Mild water stress induced a conservative water-use strategy in S. officinalis, characterized by increased root-to-shoot ratio and altered leaf morphology, without compromising photosynthetic performance. SynCom inoculation under well-watered conditions elicited drought-like responses, including transient reductions in stomatal conductance. Leaf metabolomic analysis revealed that inoculation influenced the abundance of several metabolites, including biogenic amines and dipeptides, under both irrigation regimes. Notably, drought stress and SynCom inoculation increased histamine and α-ketoglutaric acid levels, highlighting potential impacts on food quality. Under reduced irrigation, inoculation further modulated leaf morphology and biomass allocation, promoting thicker leaves and increased root biomass allocation. These results demonstrate the ability of the SynCom to modulate plant physiology and metabolism in response to both optimal and reduced irrigation, potentially enhancing drought resilience without directly improving growth. The study also highlights the complex interactions among microbial inoculation, plant stress responses, and leaf metabolite profiles, emphasizing the importance of considering the effects on the production of bioactive compounds when developing microbial inoculants for edible plants.

Urban vineyards are expanding worldwide, driven by cultural and environmental motivations and their potential contribution to sustainable food systems. This study assessed grapevine (Vitis vinifera L.) responses to urban atmospheric conditions and explored traits relevant to cultivar selection and particulate matter (PM) interception. Research was conducted during the 2025 growing season in a highly biodiverse urban vineyard comprising 170 cultivars at the Botanical Garden of Rome (Italy), a city where grapevine has been documented since antiquity. Digital phenotyping was used to screen 54 cultivars based on leaf micromorphological traits, followed by detailed assessment of five selected cultivars. Measurements also included leaf anatomical traits, chlorophyll content, spectral reflectance-derived indices related to vigor and water status, and PM interception by scanning electron microscopy. Cultivars differed in micromorphological traits and ecophysiological proxies, suggesting different responses to urban environmental conditions. Total leaf-surface PM accumulation after an approximately 20-day accumulation period following the last intense rainfall event (>10 mm h⁻¹) ranged from 52,024 particles mm⁻² in cv. Barbera to 77,462 particles mm⁻² in cv. Maturano, values broadly comparable to those reported for some urban forest species. Deposition on the adaxial surface was more than twice that measured on the abaxial surface. These findings highlight the potential of digital phenotyping to integrate morphological and physiological traits, supporting plant material selection for urban viticulture, PM interception, and, more broadly, for urban landscape design.