Coordination between leaf CO diffusion and Rubisco properties allows maximizing photosynthetic efficiency in Limonium species.

High photosynthetic efficiency intrinsically demands tight coordination between traits related to CO diffusion capacity and leaf biochemistry. Although this coordination constitutes the basis of existing mathematical models of leaf photosynthesis, it has been barely explored among closely related species, which could reveal rapid adaptation clues in the recent past. With this aim, we characterized the photosynthetic capacity of 12 species of Limonium, possessing contrasting Rubisco catalytic properties, grown under optimal (WW) and extreme drought conditions (WD). The availability of CO at the site of carboxylation (C ) determined the photosynthetic capacity of Limonium under WD, while both diffusional and biochemical components governed the photosynthetic performance under WW. The variation in the in vivo caboxylation efficiency correlated with both the concentration of active Rubisco sites and the in vitro-based properties of Rubisco, such as the maximum carboxylase turnover rate (k ) and the Michaelis-Menten constant for CO (K ). Notably, the results confirmed the hypothesis of coordination between the CO offer and demand functions of photosynthesis: those Limonium species with high total leaf conductance to CO have evolved towards increased velocity (i.e. higher k ), at the penalty of lower affinity for CO (i.e. lower specificity factor, S ).