Nanoencapsulated nitric oxide donor triggers a dose-dependent effect on the responses of maize seedlings to high light stress

• Maize felt the dynamic photoinhibition from the first day in a high-light environment. • The protective effect induced by the nanoencapsulated NO donor was dose-dependent. • GSNO-CS NPs (400 µM) provides early activation of protective mechanisms. • GSNO-CS NPs (400 µM) mitigates the photoinhibition effect on maize plants. • GSNO-CS NPs (400 µM) increased the S-nitrosothiol levels in the maize leaves. Nanoencapsulation of nitric oxide (NO) donors provides sustained release of NO, prolonging its action on plants. Here, we evaluated the action of NO-releasing chitosan nanoparticles containing GSNO (S-nitrosoglutathione) on the protection of maize plants ( Zea mays cv. Balu 787) against high light-induced stress. Experiment 1 was used to compare maize plants under different light intensities. Experiment 2 evaluated the protective effect of chitosan nanoparticles containing GSNO (NPNO) in different concentrations (200 or 400 µM). Experiment 3 compared the protective effect of NPNO to non-nanoencapsulated GSNO (NO) and nanoparticles without NO-releasing molecule (NP). In experiments 1 and 2, chlorophyll a fluorescence and gas exchange measurements were performed. In experiment 3, chlorophyll a fluorescence and biochemical analyses were carried out. In experiment 1, increases in dynamic photoinhibition (DP) of 135% (Day 1), 370% (Day 2), 206% (Day 3), and 100% (Day 5) were observed from sun plants. In experiment 2, NPNO400 showed higher levels of DP on the first (+ 148%) and second days (+ 171%), followed by a reduction on the fifth day (- 22%). For gas exchange parameters, NPNO400 attenuated the reduction in A at noon and significantly increased k , while NPNO200 decreased the k value. The differences in the effects induced by NPNO treatments are dose-dependent. In experiment 3, NPNO was the only treatment that significantly increased NO bioavailability and the activity of antioxidant enzymes (SOD; POD), contributing to mitigating stress caused by excess light on plants. The nanoencapsulation of NO donors protected maize plants against photoinhibition.