Antimicrobial peptides (AMPs) with their broad and selective antimicrobial activity and lowered risk of resistance development in microbial populations are promining as a new alternative candidate to conventional antibiotics. Plant-based expression systems can be employed as cost-effective and high scale-up capacity production hosts for recombinant expression of AMPs. LFchimera is a chimerical peptide containing LFcin and LFampin antimicrobial peptides of bovine lactoferrin, and it has stronger bactericidal activity. Here, the LFchimera sequence was codon-optimized for tobacco and fused with endoplasmic reticulum retention signals along with a CaMV 35S promoter and then transferred by agrobacterium-mediated transformation. The integration and expression of the transgene in tobacco plants were confirmed by polymerase chain reaction (PCR) and RT-PCR, respectively. Recombinant production of the peptide was confirmed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), and peptide functional activity was confirmed by the antibacterial evaluation of total protein extracts against various clinical and phytopathogenic bacteria. Finally, LFchimera peptide was partially purified using an affinity column, and the antibacterial activity was shown. Taken together, these results confirmed that tobacco can be utilized for the recombinant production of antimicrobial peptides such as LFchimera.

The phenylpropanoid pathway serves as a rich source of metabolites in plants, and it is considered as a starting point for the production of many other important compounds such as the flavonoids, flavonols, coumarins, and lignans.Scrophularia striatais a member of the Lamiaceae family with some biological activities similar to flavonoid compounds such as antioxidant, antibacterial, anti-inflammatory and analgesic activities. Cinnamate 4-hydroxylase (C4H) and Chalcone synthase (CHS) are key enzymes of the phenylpropanoid pathway, leading to the biosynthesis of several secondary metabolites. In this study, twoS. striataCHS and C4H were isolated and then analyzed. The investigation of the expression of these genes was performed under the effects of three salicylic acid (SA), jasmonic acid (JA), and gibberellic acid (GA) at concentrations of 100 and 300 ppm with a completely randomized design at the transcript level using Real Time PCR method. These have different expression patterns at developmental stages. Moreover, these genes present different sensitivities to hormonal treatment. Considering the total results, it was found that the amount of expression of these genes during the reproductive phase is higher than that of the vegetative phase. Additionally, the treatment of 300 ppm SA in the reproductive phase is the most effective treatment on increasing the corresponding phenylpropanoid compounds. A correlation analysis was performed between the phenylpropanoid compounds content and both CHS and C4H expression values at different phenological development stages. The results indicate that the expression variations of both CHS and C4H are significantly related to the changes in total phenolic content. We believe that the isolation of CHS and C4H can be helpful in better understanding phenylpropanoid metabolis.