FIGURE 2.

Maize stomatal response to climate change. (A) Heat enhances the maize stomatal responses to drought stress. Drought reduces stomatal size and opening, and increases stomatal density, which, in turn, reduces transpiration and photosynthetic rate. When drought and heat coexist, plants experience a reduction in transpiration rate and photosynthetic rate, possibly related to a reduction in stomatal size and opening, accompanied by an increase in stomatal density. This triggers a reduction in biomass accumulation, which is more severe than that induced by drought stress. (B) Possible molecular mechanisms of stomatal response to climate change. Drought stress, individually or in combination with high temperatures, reduces stomatal opening by increasing abscisic acid (ABA) levels. This stomatal response could trigger the increase of the distance of action of ZmSHR1 from the longitudinal leaf veins. ZmSHR1 might act to positively regulate ZmSPCHs/ZmICE1 heterodimers, increasing the number of stomatal files and, consequently, the stomatal density.