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

Abstract

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.