Involvement of Arabidopsis Copper Amine Oxidase β in MeJA/wounding-induced stomatal closure

The developmentally-regulated and stress-induced copper amine oxidases (CuAOs) oxidize polyamines to aminoaldehydes producing the plant signal molecule hydrogen peroxide (H2O2) and ammonia. The Arabidopsis thaliana CuAOβ encodes an apoplastic CuAO expressed in root protoxylem and in guard cells. In this study, its role in MeJA/wounding-induced stomatal closure was explored by pharmacological and genetic approaches. MeJA treatments induced stomatal closure in WT plants after 15’. Leaf/root wounding induced both local and systemic signaling leading to stomatal closure after 5’ (local response) as well as 5’ and 60’ (systemic responses to root or distal leaf wounding), while atcuaoβ insertional mutants were unresponsive.No differences in stomatal closure between WT and mutants were observed in physiological conditions. Treatment with the H2O2-scavenger N,N1-dimethylthiourea reversed the MeJA/wounding-induced stomatal closure in WT plants, suggesting a key role of the AtCuAOβ-delivered H2O2 in these event. Results suggest the AtCuAOβ involvement in MeJA/wounding-induced stomatal closure, with a dynamic implying extremely rapid long-distance leaf-to-leaf or root-to-leaf communication.