Fig. 2

Expression patterns for genes involved in the CO₂ signaling pathway of the stomata. Wild-type data are presented as an average of both wild-type genotypes. Data are presented as the average of log-transformed counts-per-million +/− standard error. Green area represents a maize guard cell. The bicarbonate pool produced by CA-medicated CO₂ hydration is sensed by RHC1. When bicarbonate levels are high, RHC1 interacts with and binds HT1. This prevents HT1 from inhibiting OST1 (indicated with dashed line). With HT1 sequestered to the plasma membrane, OST1 is able to activate SLAC1, which results in stomatal closure. As pictured here, RHC1 and SLAC1 are both expected to localize to the plasma membrane [28]