Efficacy of Magnesium Nanoparticles in Modifying Growth, Antioxidant Activity, Nitrogen Status, and Expression of WRKY1 and bZIP Transcription Factors in Pepper (Capsicum annuum); an In Vitro Biological Assessment.

This study explored the possible role of magnesium nanoparticles (nMg) on plant growth, metabolism, and gene regulation in pepper. The physiological and molecular responses of pepper plants in presence of different concentrations of nMg (75, 225, and 675 mg/L) or its bulk analog (bMg) in the culture medium were investigated. We focused on how supplementing the culture medium with nMg affected biomass accumulation, activities of several key enzymes (catalase, peroxidase, and phenylalanine ammonia-lyase (PAL)), and expression of two vital transcription factors, WRKY1 and bZIP. Our results demonstrate that nMg and bMg improved biomass accumulation in shoots and roots. The nMg treatments up-regulated the expression of two transcription factors, WRKY1 and bZIP, which are transcriptionally involved in regulating defense/stress responses and secondary metabolism. The nanomaterials enhanced the activity of nitrate reductase, a nitrogen assimilation index. The nano-supplement efficiently stimulated the activities of catalase and peroxidase. The applied treatments also induced the PAL activity, which catalyzes a checkpoint reaction in the biosynthesis of phenylpropanoids. The supplementation of culture medium with nMg augmented the concentrations of proline and phenols. This study suggests the potential contributions of WRKY1 and bZIP transcription factors in regulating plant responses to nanomaterials. Nanomaterials, such as nMg, may improve the efficiency of plant tissue cultures. [ABSTRACT FROM AUTHOR]