Further Characterization of MUAS35SCP and FUAS35SCP Recombinant Promoters and Their Implication in Translational Research.

Recombinant promoters are of high value in translational research. Earlier, we developed two recombinant promoters, namely MUAS35SCP and FUAS35SCP, and their transcriptional activities were found to be stronger than that of the most widely used CaMV35S promoter in dicot plants. Presently, we are reporting constitutive expression of both GUS and GFP reporters under the control of these promoters in several monocots, including rice, wheat, and pearl millet. We observed that these promoters could express the reporter genes constitutively, and their expression abilities were almost equal to that of the CaMV35S2 promoter. Plant-derived enriched PaDef (Persea americana var. drymifolia defensin) and NsDef2 (Nigella sativa L. defensin 2) antimicrobial peptides expressed under the control of these promoters arrest the growth of devastating phytopathogens like Pseudomonas syringae, Rhodococcus fascians, and Alternaria alternata. We observed that plant-derived NsDef2 and PaDef under control of these promoters showed approximately 80-90% inhibitory activity against Pseudomonas syringae. Hence, these promoters were constitutive and universal, as they can drive the expression of transgenes in both dicot and monocot plants. Alongside, these promoters could become a valuable tool for raising genetically modified plants with in-built resistance toward phytopathogens.

Engineering of Plants for Efficient Production of Therapeutics.

Plants are becoming useful platforms for recombinant protein production at present time. With the advancement of efficient molecular tools of genomics, proteomics, plants are now being used as a biofactory for production of different life saving therapeutics. Plant-based biofactory is an established production system with the benefits of cost-effectiveness, high scalability, rapid production, enabling post-translational modification, and being devoid of harmful pathogens contamination. This review introduces the main challenges faced by plant expression system: post-translational modifications, protein stability, biosafety concern and regulation. It also summarizes essential factors to be considered in engineering plants, including plant expression system, promoter, post-translational modification, codon optimization, and fusion tags, protein stabilization and purification, subcellular targeting, and making vaccines in an edible way. This review will be beneficial and informative to scholars and readers in the field of plant biotechnology.

Synthetic promoters from blueberry red ringspot virus (BRRV).

MAIN CONCLUSION: We analyzed the synthetic full-length transcript promoter of Blueberry red ringspot virus (BRRV) and developed two chimeric promoters (MBR3 and FBR3). Transcriptional activities of these chimeric promoters were found equivalent to that of the CaMV35S2 promoter. Chimeric promoters driven plant-derived PaDef protein showed high antimicrobial activities against several pathogens. Blueberry red ringspot virus (BRRV) is a pararetrovirus under the genus, Soymovirus belongs to the Caulimoviridae family. We have made a synthetic version of the BRRV-Flt promoter and analyzed its activity in detail. A 372 bp promoter fragment BR3 (- 212 to + 160) showed the strongest transcriptional activity compared with other fragments in both transient and transgenic assays; its activity was found near equivalent to that of the CaMV35S promoter. We constructed two chimeric promoters; MBR3 and FBR3 by fusing the UASs (Upstream activation sequences) of Mirabilis mosaic virus (MUAS; - 297 to - 38; 335 bp) and Figwort mosaic virus (FUAS; - 249 to - 54; 303 bp) respectively to the core promoter domain of BR3 (BR3; - 212 to + 160; 372 bp). The activities of MBR3 and FBR3 promoters were found equivalent to that of the activity of the CaMV35S2 promoter and approximately 4.0 (four) times stronger than that of the CaMV35S promoter. Histochemical and fluorometric GUS assays confirmed the above observation. The transcriptional efficacies of these recombinant promoters were tested by evaluating the antibacterial and antifungal activities of recombinant plant-derived antimicrobial peptide Persea americana var. drymifolia defensin (PaDef) driven under these promoters. Bioassays showed promising antifungal activities of the plant made PaDef against Alternaria alternata and antibacterial property against Gram-positive (S. aureus and R. fascians) and Gram-negative bacteria (E. coli and P. aeruginosa). Based upon the above results, MBR3 and FBR3 could be useful promoters for plant genetic engineering and can become useful substitutes for the widely used CaMV35S2 promoter in plant biology.