Oximes, peroxidases, and oxidative nitric oxide production: a new framework for plant NO metabolism?

Nitric oxide (NO) is a small, gaseous reactive species that plays key roles in plant development and responses to environmental stimuli. In mammals, NO is produced via both nitrate/nitrite reduction and the oxidation of l-arginine by nitric oxide synthase (NOS). In plants, while the reductive pathway was identified early on, a NOS-like equivalent remained elusive for decades. In this opinion article, we describe recent discoveries that suggest a modular oxidative pathway, in which peroxidases may play a key role. Together with earlier observations, this model supports a broader conceptual framework for oxidative NO production in plants, moving beyond the expectation of animal-like homologs. This serves as a reminder that plants often solve biochemical challenges in innovative ways.