Special Issue "Plant Molecular Farming"

A special issue of Plants (ISSN 2223-7747).

Deadline for manuscript submissions: closed (30 June 2020).

Special Issue Editor

Dr. Rita Abranches

Guest Editor
Plant Cell Biology Laboratory, Instituto de Tecnologia Quimica e Biologica ITQB NOVA, Universidade Nova de Lisboa, Av Republica, 2780-157 Oeiras, Portugal
Interests: molecular farming; recombinant proteins; plant cell cultures; microalgae; cell biology; epigenetics

Special Issue Information

Dear Colleagues,

It has now been 30 years since the pioneering work of Hiatt and colleagues made the cover of Nature with the report, in 1989, of the first successful expression of recombinant antibodies in plants. Since then, plant molecular farming has made great progress through years of steady activity. In 2012, when the first plant-made biopharmaceutical was approved for market release, the production of recombinant proteins in plant-based systems became a reality. Over the course of these three decades, a number of platforms have become available, ranging from whole plants to undifferentiated cultured cells. During this time, many different plant species have been used, as have individual plant organs and unicellular photosynthetic organisms.

This Special Issue of Plants will highlight the versatility of plant-based platforms for the production of recombinant proteins or other high value compounds, with a special focus on the most recent advances in the field as well as on the challenges that remain for the future.

Dr. Rita Abranches
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • molecular farming
  • recombinant proteins
  • high value compounds
  • plant-based platforms

Published Papers (6 papers)

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Research

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Open AccessArticle
Functional Improvement of Human Cardiotrophin 1 Produced in Tobacco Chloroplasts by Co-Expression with Plastid Thioredoxin m
Plants 2020, 9(2), 183; https://doi.org/10.3390/plants9020183 - 02 Feb 2020
Cited by 2
Abstract
Human cardiotrophin 1 (CT1), a cytokine with excellent therapeutic potential, was previously expressed in tobacco chloroplasts. However, the growth conditions required to reach the highest expression levels resulted in an impairment of its bioactivity. In the present study, we have examined new strategies [...] Read more.
Human cardiotrophin 1 (CT1), a cytokine with excellent therapeutic potential, was previously expressed in tobacco chloroplasts. However, the growth conditions required to reach the highest expression levels resulted in an impairment of its bioactivity. In the present study, we have examined new strategies to modulate the expression of this recombinant protein in chloroplasts so as to enhance its production and bioactivity. In particular, we assessed the effect of both the fusion and co-expression of Trx m with CT1 on the production of a functional CT1 by using plastid transformation. Our data revealed that the Trx m fusion strategy was useful to increase the expression levels of CT1 inside the chloroplasts, although CT1 bioactivity was significantly impaired, and this was likely due to steric hindrance between both proteins. By contrast, the expression of functional CT1 was increased when co-expressed with Trx m, because we demonstrated that recombinant CT1 was functionally active during an in vitro signaling assay. While Trx m/CT1 co-expression did not increase the amount of CT1 in young leaves, our results revealed an increase in CT1 protein stability as the leaves aged in this genotype, which also improved the recombinant protein’s overall production. This strategy might be useful to produce other functional biopharmaceuticals in chloroplasts. Full article
(This article belongs to the Special Issue Plant Molecular Farming)
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Open AccessArticle
Plant-Produced Recombinant Influenza A Virus Candidate Vaccine Based on Flagellin Linked to Conservative Fragments of M2 Protein and Hemagglutintin
Plants 2020, 9(2), 162; https://doi.org/10.3390/plants9020162 - 29 Jan 2020
Cited by 1
Abstract
The development of recombinant influenza vaccines with broad spectrum protection is an important task. The combination of conservative viral antigens, such as M2e, the extracellular domain of the transmembrane protein M2, and conserved regions of the second subunit of hemagglutinin (HA), provides an [...] Read more.
The development of recombinant influenza vaccines with broad spectrum protection is an important task. The combination of conservative viral antigens, such as M2e, the extracellular domain of the transmembrane protein M2, and conserved regions of the second subunit of hemagglutinin (HA), provides an opportunity for the development of universal influenza vaccines. Immunogenicity of the antigens could be enhanced by fusion to bacterial flagellin, the ligand for Toll-like receptor 5, acting as a powerful mucosal adjuvant. In this study, we report the transient expression in plants of a recombinant protein comprising flagellin of Salmonella typhimurium fused to the conserved region of the second subunit of HA (76–130 a.a.) of the first phylogenetic group of influenza A viruses and four tandem copies of the M2e peptide. The hybrid protein was expressed in Nicotiana benthamiana plants using the self-replicating potato virus X-based vector pEff up to 300 µg/g of fresh leaf tissue. The intranasal immunization of mice with purified fusion protein induced high levels of M2e-specific serum antibodies and provided protection against lethal challenge with influenza A virus strain A/Aichi/2/68(H3N2). Our results show that M2e and hemagglutinin-derived peptide can be used as important targets for the development of a plant-produced vaccine against influenza. Full article
(This article belongs to the Special Issue Plant Molecular Farming)
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Open AccessArticle
Rapid High-Yield Transient Expression of Swine Hepatitis E ORF2 Capsid Proteins in Nicotiana benthamiana Plants and Production of Chimeric Hepatitis E Virus-Like Particles Bearing the M2e Influenza Epitope
Plants 2020, 9(1), 29; https://doi.org/10.3390/plants9010029 - 24 Dec 2019
Cited by 4
Abstract
The Hepatitis E virus (HEV) is a causative agent of acute hepatitis, mainly transmitted by the fecal-oral route or zoonotic. Open reading frame (ORF) 2 encodes the viral capsid protein, which is essential for virion assembly, host interaction, and inducing neutralizing antibodies. In [...] Read more.
The Hepatitis E virus (HEV) is a causative agent of acute hepatitis, mainly transmitted by the fecal-oral route or zoonotic. Open reading frame (ORF) 2 encodes the viral capsid protein, which is essential for virion assembly, host interaction, and inducing neutralizing antibodies. In this study, we investigated whether full-length and N- and C-terminally modified versions of the capsid protein transiently expressed in N. benthamiana plants could assemble into highly-immunogenic, virus-like particles (VLPs). We also assessed whether such VLPs can act as a carrier of foreign immunogenic epitopes, such as the highly-conserved M2e peptide from the Influenza virus. Plant codon-optimized HEV ORF2 capsid genes were constructed in which the nucleotides coding the N-terminal, the C-terminal, or both parts of the protein were deleted. The M2e peptide was inserted into the P2 loop after the residue Gly556 of HEV ORF2 protein by gene fusion, and three different chimeric constructs were designed. Plants expressed all versions of the HEV capsid protein up to 10% of total soluble protein (TSP), including the chimeras, but only the capsid protein consisting of aa residues 110 to 610 (HEV 110–610) and chimeric M2 HEV 110–610 spontaneously assembled in higher order structures. The chimeric VLPs assembled into particles with 22–36 nm in diameter and specifically reacted with the anti-M2e antibody. Full article
(This article belongs to the Special Issue Plant Molecular Farming)
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Review

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Open AccessReview
Canthaxanthin, a Red-Hot Carotenoid: Applications, Synthesis, and Biosynthetic Evolution
Plants 2020, 9(8), 1039; https://doi.org/10.3390/plants9081039 - 15 Aug 2020
Abstract
Carotenoids are a class of pigments with a biological role in light capture and antioxidant activities. High value ketocarotenoids, such as astaxanthin and canthaxanthin, are highly appealing for applications in human nutraceutical, cosmetic, and animal feed industries due to their color- and health-related [...] Read more.
Carotenoids are a class of pigments with a biological role in light capture and antioxidant activities. High value ketocarotenoids, such as astaxanthin and canthaxanthin, are highly appealing for applications in human nutraceutical, cosmetic, and animal feed industries due to their color- and health-related properties. In this review, recent advances in metabolic engineering and synthetic biology towards the production of ketocarotenoids, in particular the red-orange canthaxanthin, are highlighted. Also reviewed and discussed are the properties of canthaxanthin, its natural producers, and various strategies for its chemical synthesis. We review the de novo synthesis of canthaxanthin and the functional β-carotene ketolase enzyme across organisms, supported by a protein-sequence-based phylogenetic analysis. Various possible modifications of the carotenoid biosynthesis pathway and the present sustainable cost-effective alternative platforms for ketocarotenoids biosynthesis are also discussed. Full article
(This article belongs to the Special Issue Plant Molecular Farming)
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Open AccessReview
Plant Molecular Farming: A Viable Platform for Recombinant Biopharmaceutical Production
Plants 2020, 9(7), 842; https://doi.org/10.3390/plants9070842 - 04 Jul 2020
Cited by 7
Abstract
The demand for recombinant proteins in terms of quality, quantity, and diversity is increasing steadily, which is attracting global attention for the development of new recombinant protein production technologies and the engineering of conventional established expression systems based on bacteria or mammalian cell [...] Read more.
The demand for recombinant proteins in terms of quality, quantity, and diversity is increasing steadily, which is attracting global attention for the development of new recombinant protein production technologies and the engineering of conventional established expression systems based on bacteria or mammalian cell cultures. Since the advancements of plant genetic engineering in the 1980s, plants have been used for the production of economically valuable, biologically active non-native proteins or biopharmaceuticals, the concept termed as plant molecular farming (PMF). PMF is considered as a cost-effective technology that has grown and advanced tremendously over the past two decades. The development and improvement of the transient expression system has significantly reduced the protein production timeline and greatly improved the protein yield in plants. The major factors that drive the plant-based platform towards potential competitors for the conventional expression system are cost-effectiveness, scalability, flexibility, versatility, and robustness of the system. Many biopharmaceuticals including recombinant vaccine antigens, monoclonal antibodies, and other commercially viable proteins are produced in plants, some of which are in the pre-clinical and clinical pipeline. In this review, we consider the importance of a plant- based production system for recombinant protein production, and its potential to produce biopharmaceuticals is discussed. Full article
(This article belongs to the Special Issue Plant Molecular Farming)
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Open AccessFeature PaperReview
Plant Aspartic Proteases for Industrial Applications: Thistle Get Better
Plants 2020, 9(2), 147; https://doi.org/10.3390/plants9020147 - 23 Jan 2020
Cited by 1
Abstract
Plant proteases have a number of applications in industrial processes including cheese manufacturing. The flower of the cardoon plant (Cynara cardunculus L.) is traditionally used as a milk-clotting agent in protected designation of origin cheeses made from goat and sheep milk. Plant-derived [...] Read more.
Plant proteases have a number of applications in industrial processes including cheese manufacturing. The flower of the cardoon plant (Cynara cardunculus L.) is traditionally used as a milk-clotting agent in protected designation of origin cheeses made from goat and sheep milk. Plant-derived rennets are of particular importance to consumers who wish to eat cheeses that are produced without harming any animals. In this review, we have highlighted the importance of plant proteases, particularly aspartic proteases, in industrial processes, as well as exploring more fundamental aspects of their synthesis. We have also reviewed and discussed the production of these enzymes using sustainable and cost-effective alternative platforms. Full article
(This article belongs to the Special Issue Plant Molecular Farming)
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