Ecofriendly Application of Synthetic Zinc Oxide Nanoparticles as Stress Regulator Bio-Fertilizer for Zea mays

Agricultural production is consistently threatened by stressors such as salinity. Few studies have reported on the released antioxidative enzymes and the salinity-responsive genes identified using RNA sequencing and de novo assembly in maize. To further understand the harmony between stressing the maize with a NaCl solution as a compensatory water-irrigation method and spraying regulatory zinc oxide nanoparticles (ZnO/NPs), the salinity-responsive genes were analyzed using RNA sequencing and bioinformatics tools, and the antioxidant enzymatic activities were determined. Differential expression analysis was used to uncover genes that were up-/down-regulated during the experiment. The regulatory pathways and functions of differentially expressed genes (DEGs) were estimated. Glutathione reductase/-s-transferase (GR/GST), peroxidase (POX), superoxide dismutase (SOD), and catalase (CAT) enzymes were determined spectrophotometrically. Mitigating salinity stress with 150 mM NaCl led to significant oxidative stress, markedly elevating enzyme activities: POX and GST by 275% and 254%, GR by 166%, CAT by 91%, and SOD by 56%. Treatment with ZnO/NPs alleviated this stress, decreasing enzyme activity by 61% for GST, 55% for POX, 38% for CAT, 28% for SOD, and 25% for GR. The results of RNA-seq revealed candidate genes related to changes in stressed/non-stressed maize plants, regardless of whether they were sprayed with the nanoparticles or not. This study’s results offer novel insights into the genetic traits of maize subjected to salinity stress and ZnO/nanoparticle application, thereby advancing the comprehension of how ZnO/nanoparticles might alleviate the detrimental impacts of salinity on plants whose properties were enhanced to be used in the eco-friendly synthesis of nanoparticles that were used as a bio-fertilizer in priming plants.