Understanding stomatal response to fluctuations in atmospheric carbon dioxide concentration ([CO2]) and water deficit is important to predict the overall plant performance under these two major environmental stressing factors. In Arabidopsis, slow-type anion channel (SLAC1) plays a central role in the control of stomatal closure with impacts on water use efficiency. Here we investigated whether the stomatal component also plays a central role in limiting photosynthesis in plants showing constitutive higher stomatal conductance (gs), such as slac1 mutants, under high CO2 levels and water restriction. Under these conditions, slac1 plants showed similar photosynthetic performance and growth when compared to wild-type (WT) plants. Furthermore, our results suggest that the constitutive increased stomatal aperture in slac1 plants is associated with a reorganization of primary metabolism in guard cells, in addition to the ion transport impairment, previously observed in slac1 mutants. Altogether, our results indicate that higher gs in slac1 plants are not translated into enhanced photosynthetic performance and growth, independently of CO2 levels and watering conditions.

Acesse o artigo diretamente em https://doi.org/10.1016/j.envexpbot.2025.106142