The supplementation of nutrient solution with zinc oxide affected cellular metabolism and transcription pattern in Melissa officinalis

This study investigated the molecular and physiological responses of lemon balm seedlings to the manipulation of nutrient solution with zinc oxide nanoparticle (nZnO) at 0, 100, and 300 mgl-1. The augmentation in biomass accumulation and photosynthetic pigments resulted from the nZnO utilization. The exposure of seedlings to nZnO modifed both primary and secondary metabolism in leaves. The nanosupplements upreguated activities of phenylalanine ammonia lyase and catalase enzymes. Moreover, the incease in concentrations of proline, flavonids, and glutathione resulted from the application of nZnO. Furthermore, the nZnO treatments up-regulated the transcription of phenylalanine ammonia-lyase (PAL) and Coumarate: CoA-ligase (4CL) genes, two genes responsible for the production of secondary metabolites. These comparative physiological and molecular investiagtions on plant responses to nZnO and its bulk type may serve as a theoretical basis for function in agricultural and medicinal industries.