Investigation of Antioxidative Enzymes and Transcriptomic Analysis in Response to Foliar Application of Zinc Oxide Nanoparticles and Salinity Stress in Solanum lycopersicum

Abstract

Farmers commonly throw away tomato leaves when they harvest tomatoes, although they are a good source of vital biomolecules. ZnO nanoparticles (ZnO NPs) enhance plant growth by regulating abiotic stress and scavenging reactive oxygen species. In the current article, the activities of five antioxidant enzymes—glutathione reductase (GR), peroxidase (POX), glutathione-S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT)—were determined spectrophotometrically to study the interaction between foliar fertilization of ZnO NPs and salt stress in tomato plants. We employed the next-generation sequencing (NGS) technique to investigate the gene expression. It was also used to generate a de novo supertranscript and then determine the sequences modulated by treatments. Differential expression analysis was used to identify increased and reduced gene clusters, and gene enrichment analysis was used to identify over- and under-expressed genes under the treatment. Gene Ontology (GO) was used to identify the functions and regulatory pathways of the differentially expressed genes (DEGs). It was found that ZnO nanoparticles had the capability to overcome the reduction in antioxidant enzyme production levels in the case of the salinity-stressed treatments and enhance the secretion of those enzymes in the non-stressed but sprayed treatments. The ZnO NPs also enhanced the reduction in stress-responsive genes associated with salt stress resistance. The results revealed the impact of ZnO nanoparticles on alleviating the salinity stress reductive effects in antioxidative enzymes and regulating the mechanism by which metabolically relevant genes adaptively respond to salt stress in tomato plants. So, spraying tomato plants (stressed or not) with ZnO NPs is a promising agricultural technique in improving different metabolic pathways that are responsible for plants’ resistance.