Heavy metal (HM) emissions have increased due to the impact of rising urbanization and anthropogenic activity, affecting different parts of the environment. The goal of this study is to investigate the combined effect of ZnO NPs and bacteria treatment on protein and gene expression profiles of rice plants that are grown in HMs-polluted water. Seeds were primed with Bacillus spp. (Bacillus cereus and Lysinibacillus macroides) before being cultured in Hoagland media containing ZnO NPs (5 and 10 mg/L) and HMs-contaminated water from the Hayatabad industrial estate (HIE), Peshawar, Pakistan. The results revealed that the maximum nitrogen and protein content was observed in the root, shoot, and leaf of the plant grown by combining bacteria-ZnO NPs treatment under HMs stress as compared with plant grown without or with individual treatments of ZnO NPs and bacteria. Furthermore, protein expression analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) revealed that plants that were grown in HMs-polluted water were found to be affected in contaminated water, however the combined effect of bacteria-ZnO NPs reported the more dense protein profile as compared with their individual treatments. Subsequently, plants that were grown in HMs-polluted water have the highest expression levels of stress-induced genes such as myeloblastosis (Myb), zinc-finger protein (Zat-12), and ascorbate peroxidase (Apx) while the combined effect revealed minimum expression as compared with individual treatments. It is concluded that the combined effect of ZnO NPs and bacteria lowered the stress-induced gene expression while it increased the nitrogen-protein content and protein expression in plant grown under HMs stress.
Keywords: bacteria; gel electrophoresis; heavy metals; nanoparticles; transcription factors; zinc oxide nanoparticles.