Fe2 O3 NPs induced biochemical responses and expression of genes involved in rosmarinic acid biosynthesis pathway in Moldavian balm under salinity stress.

The effect of iron oxide nanoparticle at four concentrations (0, 30, 60 and 90 ppm) and salinity at three levels (0, 50 and 100 mM) were investigated on rosmarinic acid (RA) production in five-week-old Moldavian balm (Dracocephalum moldavica L.) plants. Salinity and spraying iron oxide nanoparticles (NPs) significantly affected Tyr, Phe and Pro amino acids content, PAL, TAT and RAS genes expression levels, RA content, PPO, PAL and SOD activities, MDA content and DPPH radical scavenging activity. PAL, TAT and RAS genes expression rate and content of RA enhanced in Moldavian dragonhead plants exposed by NaCl+NPs. The results of HPLC revealed that simultaneous application of 50 mM NaCl +90 ppm NPs increase the RA content in leaf about 81.15% as compared to control plants. The Tyr and Phe contents were decreased in Moldavian balm plants exposed to salt stress. Application of NPs had a positive effect on the content of these amino acids. Proline content increased under salinity stress and application of iron NPs induced a significant increase in the Pro content of leaf. The results revealed that PAL, PPO and SOD enzymes activities increased under salinity conditions. The highest activity of PPO and SOD was observed in 100 mM NaCl +60 ppm NPs treatment. Simultaneous application of 100 mM NaCl +90 ppm NPs increased the MDA content and DPPH radical scavenging activity compared to control plants. It can be concluded that the application of appropriate levels of NPs moderate the effect of salinity stress in Dracocephalum moldavica L. and results in increased amount of rosmarinic acid compared to control plants. This article is protected by copyright. All rights reserved.