Biodegradable glycine betaine encapsulated chitosan nanoparticles induce the expression of antioxidant enzyme genes to improve drought tolerance in maize

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Drought is one of the main abiotic stresses that affect the growth and development of maize crop, thus causing food crises across the world. Nanoparticles are considered an effective tool for improving crop yield by upgrading the plant tolerance mechanism under abiotic stress. In this study, we investigated the role of foliar application of glycine betaine-encapsulated chitosan loaded nanoparticles (LNPs) and unloaded chitosan nanoparticles (NPs) in improving morphological, physiological, biochemical and molecular attributes in two maize varieties, HNG and CZP, grown under drought stress. Petri plates experiment was performed to screen different levels of drought (5 % and 20 %) and nanoparticle concentrations (10, 20 and 40 μg NPs). In the pot experiment, 20 % drought stress along with 20 μg LNPs and 20 μg NPs were used to examine the morphological, physiological and biochemical attributes of maize plants. Drought stress led to a significant reduction in fresh and dry weight, relative water content, root and shoot lengths, photosynthetic pigments, and antioxidant enzyme activities, including catalase, superoxide dismutase, ascorbate peroxidase, and proline content compared to control plants. However, foliar application of LNPs resulted in increased photosynthetic pigments, enhanced antioxidant enzyme activity, and elevated proline content under both control and drought-stressed conditions. Conversely, malondialdehyde (MDA) content decreased significantly with the application of LNPs and NPs alone under stress conditions. Moreover, nanoparticles also enhanced the relative expression levels of antioxidant genes, ZmAPX, ZmCAT, and ZmSOD. These findings highlight the potential of LNPs as an ecofriendly which helps in ameliorating drought stress in maize, and other plants.