2022-05-232022-05-232019Franco Navarro, J.d.D., Rosales Villegas, M.Á., Cubero Font, P., Álvarez Morales, R., Calvo Ruiz, P., Díaz Espejo, A. y Colmenero Flores, J.M. (2019). Chloride as a macronutrient increases water-use efficiency by anatomically driven reduced stomatal conductance and increased mesophyll diffusion to CO2. Plant Journal, 99 (5), 815-831. https://doi.org/10.1111/tpj.14423.0960-74121365-313Xhttps://hdl.handle.net/11441/133544Chloride (Cl−) has been recently described as a beneficial macronutrient, playing specific roles in promoting plant growth and water-use efficiency (WUE). However, it is still unclear how Cl− could be beneficial, especially in comparison with nitrate (NO3 −), an essential source of nitrogen that shares with Cl− similar physical and osmotic properties, as well as common transport mechanisms. In tobacco plants, macronutrient levels of Cl− specifically reduce stomatal conductance (gs) without a concomitant reduction in the net photosynthesis rate (AN). As stomata-mediated water loss through transpiration is inherent in the need of C3 plants to capture CO2, simultaneous increase in photosynthesis and WUE is of great relevance to achieve a sustainable increase in C3 crop productivity. Our results showed that Cl−-mediated stimulation of larger leaf cells leads to a reduction in stomatal density, which in turn reduces gs and water consumption. Conversely, Cl− improves mesophyll diffusion conductance to CO2 (gm) and photosynthetic performance due to a higher surface area of chloroplasts exposed to the intercellular airspace of mesophyll cells, possibly as a consequence of the stimulation of chloroplast biogenesis. A key finding of this study is the simultaneous improvement of AN and WUE due to macronutrient Cl− nutrition. This work identifies relevant and specific functions in which Cl− participates as a beneficial macronutrient for higher plants, uncovering a sustainable approach to improve crop yield.application/pdf17 p.engAttribution-NonCommercial-NoDerivatives 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc-nd/4.0/Beneficial macronutrientChloride nutritionChloroplastMesophyll diffusion conductance to CO2Nicotiana tabacumNitratePhotosynthesisStomatal conductanceStomatal densityWater-use efficiencyinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess10.1111/tpj.14423