Unprecedented enhancement of recombinant protein production in sugarcane culms using a combinatorial promoter stacking system

Enhancing medicinal proteins production in plant bioreactors: A focal review on promoters

The use of plant bioreactors for the production of medicinal proteins has emerged as a promising and cost-effective alternative to traditional microbial and mammalian cell culture systems. This review provides a focused examination of the critical role of promoters in enhancing the production of therapeutic proteins within plant-based platforms. We discuss the latest advancements in promoter discovery, modification, and optimization for the expression of medicinal proteins in plants. The review highlights the challenges and opportunities associated with various types of promoters, including constitutive, tissue-specific, and inducible promoters, and their impact on medicinal protein yield and quality. Case studies are presented to illustrate the successful application of these promoter engineering techniques in plant bioreactors, emphasizing the potential for scalable and sustainable production of pharmaceutical proteins. Additionally, we explore the strategies for improving promoter function. This review is intended to guide researchers and industry professionals in the selection and design of promoters for the enhanced production of medicinal proteins in plant bioreactors.

Incorporation of regulatory DNA elements within a viral vector improves recombinant protein expression in plants

Plants have significant potential as recombinant protein expression chassis, as they can produce complex post-translationally modified proteins that are unobtainable using prokaryotic production systems, with almost limitless scalability and substantially reduced costs relative to eukaryotic cell cultures. Transient protein expression reduces the time taken between transformation and recombinant protein extraction and purification, however low protein yields relative to conventional stable expression systems remain a major obstacle. Here, we have assessed the effectiveness of combining several established genetic components, including a promoter, 5' UTR, 3' UTR, double terminator, and matrix attachment region, to modify the TMV-based pJL-TRBO expression vector for improved recombinant protein expression in plants. Using enhanced green fluorescent protein (eGFP) as a reporter, we quantified expression using fluorescence imaging in planta together with SDS-PAGE and western blotting and showed that our optimum construct resulted in a significant increase relative to pJL-TRBO-eGFP. This increase was exclusively due to the presence of the additional 5' UTR. We anticipate that our expression constructs will be a useful tool for high-yield plant recombinant protein production and may serve as a template for further improvements.

Over expression of modified Isomaltulose Synthase Gene II (ImSyGII) under single and double promoters drive unprecedented sugar contents in sugarcane

Sugarcane has been grown all around the world to meet sugar demands for industrial sector. The current sugar recovery percentage in sugarcane cultivars is dismally low which demands scientific efforts for improvements. Multiple approaches were adopted to enhance sugar contents in commercial sugarcane plants in contrast to conventional plant breeding methods. The exploitation of biotechnological methods and exploration of isomaltulose synthetic genes presented a promising solution to increase the existing low level of sugar recovery percentage in Saccharum officinarum L. Isomaltulose synthase gene II was employed and integrated into plant expression vector driven under the leaf and stem specific promoters terminated by nopaline synthase gene in a cloning strategy shown in the present study. Three gene constructs were developed in various combinations driven under promoters Zea mays ubiquitin and Cestrum Yellow Leaf Curl virus in the single and double combined stacked system. The transformation was executed in multiple formats with single transformed events, double promoter transformation events and triple construct stacked promoters in sugarcane induced calli via the particle gene gun. The transformation of ImSyGII in sugarcane genotype HSF-240 was confirmed by molecular gene analysis while expression quantification was determined through Real Time PCR. Furthermore, HPLC was also done to harvest the increased amounts of Isomaltulose in transgenic sugarcane juice. The present work upheld the enhanced ImSyGII expression in leaves owing to the exploitation of ubiquitin, while the Cestrum Yellow Leaf Curl virus promoter enhanced gene expression in sugarcane stems. The employment of three gene constructs collectively produced elite sugar lines producing more than 78% enhancements in whole sugar recovery percentage. The mature internode proved highly efficient and receptive regarding the production of isomaltulose. Quantifications and sugar contents evaluations upheld an increased Brix ratio of transgenic sugarcane lines than control lines.

Production of Plant Proteins and Peptides with Pharmacological Potential

The use of plant proteins or peptides in biotechnology is based on their identification as possessing bioactive potential in plants. This is usually the case for antimicrobial, fungicidal, or insecticidal components of the plant's defense system. They function in addition to a large number of specialized metabolites. Such proteins can be classified according to their sequence, length, and structure, and this has been tried to describe for a few examples here. Even though such proteins or peptides can be induced during plant-pathogen interaction, they are still present in rather small amounts that make the system not suitable for the production in large-scale systems. Therefore, a suitable type of host needs to be identified, such as cell cultures or adult plants. Bioinformatic predictions can also be used to add to the number of bioactive sequences. Some problems that can occur in production by the plant system itself will be discussed, such as choice of promoter for gene expression, posttranslational protein modifications, protein stability, secretion of proteins, or induction by elicitors. Finally, the plant needs to be set up by biotechnological or molecular methods for production, and the product needs to be enriched or purified. In some cases of small peptides, a direct chemical synthesis might be feasible. Altogether, the process needs to be considered marketable.

Optimising expression and extraction of recombinant proteins in plants

Recombinant proteins are of paramount importance for research, industrial and medical use. Numerous expression chassis are available for recombinant protein production, and while bacterial and mammalian cell cultures are the most widely used, recent developments have positioned transgenic plant chassis as viable and often preferential options. Plant chassis are easily maintained at low cost, are hugely scalable, and capable of producing large quantities of protein bearing complex post-translational modification. Several protein targets, including antibodies and vaccines against human disease, have been successfully produced in plants, highlighting the significant potential of plant chassis. The aim of this review is to act as a guide to producing recombinant protein in plants, discussing recent progress in the field and summarising the factors that must be considered when utilising plants as recombinant protein expression systems, with a focus on optimising recombinant protein expression at the genetic level, and the subsequent extraction and purification of target proteins, which can lead to substantial improvements in protein stability, yield and purity.

Plant-based expression platforms to produce high-value metabolites and proteins

Plant-based heterologous expression systems can be leveraged to produce high-value therapeutics, industrially important proteins, metabolites, and bioproducts. The production can be scaled up, free from pathogen contamination, and offer post-translational modifications to synthesize complex proteins. With advancements in molecular techniques, transgenics, CRISPR/Cas9 system, plant cell, tissue, and organ culture, significant progress has been made to increase the expression of recombinant proteins and important metabolites in plants. Methods are also available to stabilize RNA transcripts, optimize protein translation, engineer proteins for their stability, and target proteins to subcellular locations best suited for their accumulation. This mini-review focuses on recent advancements to enhance the production of high-value metabolites and proteins necessary for therapeutic applications using plants as bio-factories.

Maximizing the Production of Recombinant Proteins in Plants: From Transcription to Protein Stability

The production of therapeutic and industrial recombinant proteins in plants has advantages over established bacterial and mammalian systems in terms of cost, scalability, growth conditions, and product safety. In order to compete with these conventional expression systems, however, plant expression platforms must have additional economic advantages by demonstrating a high protein production yield with consistent quality. Over the past decades, important progress has been made in developing strategies to increase the yield of recombinant proteins in plants by enhancing their expression and reducing their degradation. Unlike bacterial and animal systems, plant expression systems can utilize not only cell cultures but also whole plants for the production of recombinant proteins. The development of viral vectors and chloroplast transformation has opened new strategies to drastically increase the yield of recombinant proteins from plants. The identification of promoters for strong, constitutive, and inducible promoters or the tissue-specific expression of transgenes allows for the production of recombinant proteins at high levels and for special purposes. Advances in the understanding of RNAi have led to effective strategies for reducing gene silencing and increasing recombinant protein production. An increased understanding of protein translation, quality control, trafficking, and degradation has also helped with the development of approaches to enhance the synthesis and stability of recombinant proteins in plants. In this review, we discuss the progress in understanding the processes that control the synthesis and degradation of gene transcripts and proteins, which underlie a variety of developed strategies aimed at maximizing recombinant protein production in plants.

Enhancement of healthful novel sugar contents in genetically engineered sugarcane juice integrated with molecularly characterized ThSyGII (CEMB-SIG2)

Enhancement of sugar contents and yielding healthful sugar products from sugarcane demand high profile scientific strategies. Previous efforts to foster manipulation in metabolic pathways or triggering sugar production through combating abiotic stresses fail to yield high sugar recovery in Saccharum officinarum L. Novel sucrose isomers trehalulose (TH) and isomaltulose (IM) are naturally manufactured in microbial sources. In pursuance of novel scientific methodology, codon optimized sucrose isomerase gene, Trehalulose synthase gene II(CEMB-SIG2) cloned under dual combined stem specific constitutive promoters in pCAMBIA1301 expression vector integrated with Vacuole targeted signal peptide (VTS) to concentrate gene product into the vacuole. The resultant mRNA expression obtained by Real Time PCR validated extremely increased transgene expression in sugarcane culms than leaf tissues. Overall sugar estimation from transgenic sugarcane lines was executed through refractometer. HPLC based quantifications of Trehalulose (TH) alongside different internodes of transgenic sugarcane confirmed the enhancement of boosted sugar concentrations in mature sugarcane culms. Trehalulose synthase gene II receptive sugarcane lines indicated the unprecedented impressions of duly combined constitutive stem regulated promoters. Transgenic sugarcane lines produce highest sugar recovery percentages, 14.9% as compared to control lines (8.5%). The increased sugar recovery percentage in transgenic sugarcane validated the utmost performance and expression of ThSyGII gene .High Profile Liquid chromatography based sugar contents estimation of Trehalulose (TH) and Isomaltulose (IM) yielded unprecedented improvement in the whole sugar recovery percentage as compared to control lines.⁠.

Sugarcane Rhizosphere Bacteria Community Migration Correlates with Growth Stages and Soil Nutrient

Plants and rhizosphere bacterial microbiota have intimate relationships. As neighbors of the plant root system, rhizosphere microorganisms have a crucial impact on plant growth and health. In this study, we sampled rhizosphere soil of sugarcane in May (seedling), July (tillering), September (elongation) and November (maturity), respectively. We employ 16S rRNA amplicon sequencing to investigate seasonal variations in rhizosphere bacteria community structure and abundance, as well as their association with soil edaphic factors. The results demonstrate that soil pH, total nitrogen (TN) and available nitrogen (AN) decrease substantially with time. Rhizosphere bacteria diversity (Shannon) and the total enriched OTUs are also significantly higher in July relative to other months. Bacteria OTUs and functional composition exhibit a strong and significant correlation with soil temperature (Tem), suggesting that Tem was the potential determinant controlling rhizosphere bacteria diversity, enriched OTUs as well as functional composition. Redundancy analysis (RDA) point toward soil total potassium (TK), pH, TN, Tem and AN as principal determinant altering shifting bacteria community structure. Variation partitioning analysis (VPA) analysis further validate that a substantial proportion of variation (70.79%) detected in the rhizosphere bacteria community structure was attributed to edaphic factors. Mfuzz analysis classified the bacterial genera into four distinct clusters, with cluster two exhibiting a distinct and dramatic increase in July, predominantly occupied by Allocatelliglobosispora. The stochastic forest model found the key characteristic bacterial populations that can distinguish the four key growth periods of sugarcane. It may help us to answer some pending questions about the interaction of rhizosphere microorganisms with plants in the future.

Genetic Manipulation of Biosynthetic Pathways in Mint

In recent years, the study of aromatic plants has seen an increase, with great interest from industrial, academic, and pharmaceutical industries. Among plants attracting increased attention are the Mentha spp. (mint), members of the Lamiaceae family. Mint essential oils comprise a diverse class of molecules known as terpenoids/isoprenoids, organic chemicals that are among the most diverse class of naturally plant derived compounds. The terpenoid profile of several Mentha spp. is dominated by menthol, a cyclic monoterpene with some remarkable biological properties that make it useful in the pharmaceutical, medical, cosmetic, and cleaning product industries. As the global market for Mentha essential oils increases, the desire to improve oil composition and yield follows. The monoterpenoid biosynthesis pathway is well characterised so metabolic engineering attempts have been made to facilitate this improvement. This review focuses on the Mentha spp. and attempts at altering the carbon flux through the biosynthetic pathways to increase the yield and enhance the composition of the essential oil. This includes manipulation of endogenous and heterologous biosynthetic enzymes through overexpression and RNAi suppression. Genes involved in the MEP pathway, the menthol and carvone biosynthetic pathways and transcription factors known to affect secondary metabolism will be discussed along with non-metabolic engineering approaches including environmental factors and the use of plant growth regulators.

Effects of plant growth regulators on transient expression of foreign gene in Nicotiana benthamiana L. leaves

BACKGROUND

In the last decades, replicating expression vectors based on plant geminivirus have been widely used for enhancing the efficiency of plant transient expression. By using the replicating expression vector derived from bean yellow dwarf virus and green fluorescent protein as a reporter, we investigated the effects of α-naphthalene acetic acid, gibberellins3, and 6-benzyladenine, as three common plant growth regulators, on the plant biomass and efficiency of transient expression during the process of transient expression in Nicotiana benthamiana L. leaves.

RESULTS

With the increase of the concentration of α-naphthalene acetic acid, gibberellins3, and 6-benzyladenine (from 0.1 to 1.6 mg/L), the fresh weight, dry weight, and leaf area of the seedlings increased first and then returned to the levels similar to the controls (without chemical treatment). The treatment with α-naphthalene acetic acid at 0.2 and 0.4 mg/L can enhance the level of transient expression of green fluorescent protein, which peaked at 0.4 mg/L α-naphthalene acetic acid and was increased about by 19%, compared to the controls. Gibberellins3 at 0.1-0.4 mg/L can enhance the level of transient expression of green fluorescent protein, which peaked at 0.2 mg/L gibberellins3 and was increased by 25%. However, the application of 6-benzyladenine led to decrease in the level of transient expression of green fluorescent protein.

CONCLUSIONS

The appropriate plant growth regulators at moderate concentration could be beneficial to the expression of foreign genes from the Agrobacterium-mediated transient expression system in plants. Thus, appropriate plant growth regulators could be considered as exogenous components that are applied for the production of recombinant protein by plant-based transient expression systems.