Identification of SLAC1 anion channel residues required for CO 2 /bicarbonate sensing and regulation of stomatal movements

Significance Plants optimize CO 2 influx for photosynthesis and water loss by regulating gas exchange between the inside of leaves and the atmosphere via stomatal pores. Respiration in darkness and the continuing atmospheric CO 2 rise cause closing of stomatal pores, thus affecting plant water loss globally. However, the mechanisms by which plant guard and mesophyll cells sense CO 2 /bicarbonate for CO 2 regulation of stomata remain unknown. Here, a computer-aided modeling approach and multiple experimental assays suggest that the anion channel SLAC1 plays an important role in CO 2 /bicarbonate sensing in guard cells. This work will aid in the understanding of how plants cope with the increasing CO 2 concentration and can further lead to new approaches for developing crop plants to adapt to climate change.