Figure 14.

Working Model of PA Activation of Rboh in ABA-Induced Stomatal Closure in Arabidopsis.

ABA stimulates PLD activity probably through a putative ABA receptor. The lipid messenger PA produced by ABA activation of PLD binds to Rboh in the cytolosolic region of the N terminus. The activation of Rboh by PA binding results in ROS production (including H₂O₂). The PA–ABI1 interaction impairs ABI1 inhibition of H₂O₂ and NO signaling. Possible interactions between the identified components and other intermediates are discussed in the Discussion. The double red lines between ABI1 and stomatal closing indicate that the recruitment of ABI1 to the plasma membrane impairs ABI1 inhibition of stomatal closing.