Ozone Induced Stomatal Regulations, MAPK and Phytohormone Signaling in Plants

Ozone (O₃) is a gaseous environmental pollutant that can enter leaves through stomatal pores and cause damage to foliage. It can induce oxidative stress through the generation of reactive oxygen species (ROS) like hydrogen peroxide (H₂O₂) that can actively participate in stomatal closing or opening in plants. A number of phytohormones, including abscisic acid (ABA), ethylene (ET), salicylic acid (SA), and jasmonic acid (JA) are involved in stomatal regulation in plants. The effects of ozone on these phytohormones' ability to regulate the guard cells of stomata have been little studied, however, and the goal of this paper is to explore and understand the effects of ozone on stomatal regulation through guard cell signaling by phytohormones. In this review, we updated the existing knowledge by considering several physiological mechanisms related to stomatal regulation after response to ozone. The collected information should deepen our understanding of the molecular pathways associated with response to ozone stress, in particular, how it influences stomatal regulation, mitogen-activated protein kinase (MAPK) activity, and phytohormone signaling. After summarizing the findings and noting the gaps in the literature, we present some ideas for future research on ozone stress in plants.