Reactive oxygen species and nitric oxide as mediators in plant hypersensitive response and stomatal closure

Abstract

Nitric oxide (NO) and reactive oxygen species (ROS) have attracted considerable interest from plant pathologists since they regulate plant defenses via the hypersensitive response (HR) and stomatal closure. Here, we introduce the regulatory mechanisms of NO and ROS bursts and discuss the role of such bursts in HR and stomatal closure. It showed that epidermal sections of leaves respond to pathogens by the rapid and intense production of intracellular ROS and NO. Oxidative stress and H₂O₂ induce stomatal closure. Catalase and peroxidase-deficient plants are also hyperresponsive to pathogen invasion, suggesting a role for H₂O₂ in HR-mediated cell death. The analysis reveals that ROS and NO play important roles in stomatal closure and HR that involves multiple pathways. Therefore, multi-disciplinary and multi-omics combined analysis is crucial to the advancement of ROS and NO research and their role in plant defense mechanism.

Keywords: Effector; hypersensitive response; nitric oxide; reactive oxygen species; stomatal closure.

Figure 1.

Production of NO and ROS. (a) Nitric oxide production includes synthesis by nitric oxide synthase (NOS), nitrite reduction by nitrate reductase (NR) and non-enzymatic NO generation (NENGS). (b) ROS is produced by several enzymes including NADPH oxidase, peroxidase, oxalate oxidase, and copper-containing amine oxidases.

Figure 2.

ROS and NO in stomatal closure. ABA and pathogen through activating RbohD/F and accumulation of H₂O₂ and NO promote stomatal closure. NR: nitrate reductase; NOS: nitric oxide synthase.