Plant hormone signal integration in guard cells

Abstract

Stomata regulate carbon dioxide uptake and transpirational water loss rates upon environmental fluctuation. The plant hormone abscisic acid (ABA) and methyljasmonate (MeJA) induce stomatal closure under drought and biological stresses, respectively. In Arabidopsis, several genetic factors involving in ABA and MeJA signaling pathways in guard cells have been identified, such as protein phosphatase components ABI1, ABI2 and RCN1, and protein kinases OST1 and CDPKs. In order to understand the signal integration process in guard cells, signal events (reactive oxygen species generation, Ca²⁺ and anion channel activation) were examined in the mutants defective in such signaling components. Our results depict the outline of early signal integration in ABA and MeJA signaling in guard cells.