Green light modulates disease resistance in Arabidopsis thaliana against Pseudomonas syringae pv. tomato

Light plays a pivotal role in regulating plant physiological processes. However, the influence of specific light wavelengths on plant defense to pathogen infection remains insufficiently explored. We investigated the role of different light wavelengths, with a particular focus on green light (GL), in modulating disease responses and signaling in Arabidopsis. We pretreated Arabidopsis Col-0 plants with various light wavelengths before challenging them with Pseudomonas syringae pv. tomato DC3000 (PstDC3000). GL at an intensity of 100 µmol m^–2 s^–1 significantly suppressed disease incidence compared to white light (WL). GL upregulated the expression of key defense-related genes, including COI1, JAR1, PDF1.2, and PAD4, compared to WL. Furthermore, GL promoted callose deposition and reduced H₂O₂ production relative to the WL treatment. Jasmonic acid (JA)-deficient mutants (∆Jar1 and ∆Coi1) exhibited heightened disease severity under GL treatment compared with that of Col-0, underscoring the central role of the JA pathway in GL-mediated defense responses. These results indicate that GL functions as a crucial modulator of the defense response in Arabidopsis, offering new insights into the relationship between light quality and plant immunity. However, further research is required to elucidate the precise perception mechanisms and signaling networks involved in GL-mediated defense responses.