%0 Journal Article %A Liina Jakobson %A Lauri Vaahtera %A Kadri Tõldsepp %A Maris Nuhkat %A Cun Wang %A Yuh-Shuh Wang %A Hanna Hõrak %A Ervin Valk %A Priit Pechter %A Yana Sindarovska %A Jing Tang %A Chuanlei Xiao %A Yang Xu %A Ulvi Gerst Talas %A Maido Remm %A Saijaliisa Kangasjärvi %A M. Rob G. Roelfsema %A Honghong Hu %A Jaakko Kangasjärvi %A Mart Loog %A Julian I. Schroeder %A Hannes Kollist %A Mikael Brosché %T Natural Variation in Arabidopsis Cvi-0 Accession Uncovers Regulation of Guard Cell CO2 Signaling by MPK12 %D 2016 %R 10.1101/073015 %J bioRxiv %P 073015 %X Plant gas exchange is regulated by guard cells that form stomatal pores. Stomatal adjustments are crucial for plant survival; they regulate uptake of CO2 for photosynthesis, loss of water and entrance of air pollutants such as ozone. We mapped ozone hypersensitivity, more open stomata and stomatal CO2-insensitivity phenotypes of the Arabidopsis thaliana accession Cvi-0 to a single amino acid substitution in MAP kinase 12 (MPK12). In parallel we showed that stomatal CO2-insensitivity phenotypes of a mutant cis (CO2-insensitive) were caused by a deletion of MPK12. Lack of MPK12 impaired bicarbonate-induced activation of S-type anion channels. We demonstrated that MPK12 interacted with the protein kinase HT1, a central node in guard cell CO2 signaling, and that MPK12 can function as an inhibitor of HT1. These data provide a new function for plant MPKs as protein kinase inhibitors and suggest a mechanism through which guard cell CO2 signaling controls plant water management. %U https://www.biorxiv.org/content/biorxiv/early/2016/09/01/073015.full.pdf