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Schmidt JA, Richter LV, Condoluci LA, Ahner BA. Mitigation of deleterious phenotypes in chloroplast-engineered plants accumulating high levels of foreign proteins. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:42. [PMID: 33568217 PMCID: PMC7877051 DOI: 10.1186/s13068-021-01893-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 01/28/2021] [Indexed: 05/19/2023]
Abstract
BACKGROUND The global demand for functional proteins is extensive, diverse, and constantly increasing. Medicine, agriculture, and industrial manufacturing all rely on high-quality proteins as major active components or process additives. Historically, these demands have been met by microbial bioreactors that are expensive to operate and maintain, prone to contamination, and relatively inflexible to changing market demands. Well-established crop cultivation techniques coupled with new advancements in genetic engineering may offer a cheaper and more versatile protein production platform. Chloroplast-engineered plants, like tobacco, have the potential to produce large quantities of high-value proteins, but often result in engineered plants with mutant phenotypes. This technology needs to be fine-tuned for commercial applications to maximize target protein yield while maintaining robust plant growth. RESULTS Here, we show that a previously developed Nicotiana tabacum line, TetC-cel6A, can produce an industrial cellulase at levels of up to 28% of total soluble protein (TSP) with a slight dwarf phenotype but no loss in biomass. In seedlings, the dwarf phenotype is recovered by exogenous application of gibberellic acid. We also demonstrate that accumulating foreign protein represents an added burden to the plants' metabolism that can make them more sensitive to limiting growth conditions such as low nitrogen. The biomass of nitrogen-limited TetC-cel6A plants was found to be as much as 40% lower than wildtype (WT) tobacco, although heterologous cellulase production was not greatly reduced compared to well-fertilized TetC-cel6A plants. Furthermore, cultivation at elevated carbon dioxide (1600 ppm CO2) restored biomass accumulation in TetC-cel6A plants to that of WT, while also increasing total heterologous protein yield (mg Cel6A plant-1) by 50-70%. CONCLUSIONS The work reported here demonstrates that well-fertilized tobacco plants have a substantial degree of flexibility in protein metabolism and can accommodate considerable levels of some recombinant proteins without exhibiting deleterious mutant phenotypes. Furthermore, we show that the alterations to protein expression triggered by growth at elevated CO2 can help rebalance endogenous protein expression and/or increase foreign protein production in chloroplast-engineered tobacco.
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Affiliation(s)
- Jennifer A Schmidt
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA.
| | - Lubna V Richter
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Lisa A Condoluci
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Beth A Ahner
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
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Schmidt JA, McGrath JM, Hanson MR, Long SP, Ahner BA. Field-grown tobacco plants maintain robust growth while accumulating large quantities of a bacterial cellulase in chloroplasts. NATURE PLANTS 2019; 5:715-721. [PMID: 31285558 DOI: 10.1038/s41477-019-0467-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 06/04/2019] [Indexed: 06/09/2023]
Abstract
High accumulation of heterologous proteins expressed from the plastid genome has sometimes been reported to result in compromised plant phenotypes. Comparisons of transplastomic plants to wild-type (WT) are typically made in environmentally controlled chambers with relatively low light; little is known about the performance of such plants under field conditions. Here, we report on two plastid-engineered tobacco lines expressing the bacterial cellulase Cel6A. Field-grown plants producing Cel6A at ~20% of total soluble protein exhibit no loss in biomass or Rubisco content and only minor reductions in photosynthesis compared to WT. These experiments demonstrate that, when grown in the field, tobacco possesses sufficient metabolic flexibility to accommodate high levels of recombinant protein by increasing total protein synthesis and accumulation and/or by reallocating unneeded endogenous proteins. Based on current tobacco cultivation practices and readily achievable recombinant protein yields, we estimate that specific proteins could be obtained from field-grown transgenic tobacco plants at costs three orders of magnitude less than current cell culture methods.
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Affiliation(s)
- Jennifer A Schmidt
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Justin M McGrath
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Urbana, IL, USA
| | - Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Stephen P Long
- Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, IL, USA
- Department of Crop Sciences, University of Illinois, Urbana-Champaign, Urbana, IL, USA
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Beth A Ahner
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA.
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3
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Pasoreck EK, Su J, Silverman IM, Gosai SJ, Gregory BD, Yuan JS, Daniell H. Terpene metabolic engineering via nuclear or chloroplast genomes profoundly and globally impacts off-target pathways through metabolite signalling. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:1862-75. [PMID: 27507797 PMCID: PMC4980996 DOI: 10.1111/pbi.12548] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/03/2016] [Accepted: 02/08/2016] [Indexed: 05/09/2023]
Abstract
The impact of metabolic engineering on nontarget pathways and outcomes of metabolic engineering from different genomes are poorly understood questions. Therefore, squalene biosynthesis genes FARNESYL DIPHOSPHATE SYNTHASE (FPS) and SQUALENE SYNTHASE (SQS) were engineered via the Nicotiana tabacum chloroplast (C), nuclear (N) or both (CN) genomes to promote squalene biosynthesis. SQS levels were ~4300-fold higher in C and CN lines than in N, but all accumulated ~150-fold higher squalene due to substrate or storage limitations. Abnormal leaf and flower phenotypes, including lower pollen production and reduced fertility, were observed regardless of the compartment or level of transgene expression. Substantial changes in metabolomes of all lines were observed: levels of 65-120 unrelated metabolites, including the toxic alkaloid nicotine, changed by as much as 32-fold. Profound effects of transgenesis on nontarget gene expression included changes in the abundance of 19 076 transcripts by up to 2000-fold in CN; 7784 transcripts by up to 1400-fold in N; and 5224 transcripts by as much as 2200-fold in C. Transporter-related transcripts were induced, and cell cycle-associated transcripts were disproportionally repressed in all three lines. Transcriptome changes were validated by qRT-PCR. The mechanism underlying these large changes likely involves metabolite-mediated anterograde and/or retrograde signalling irrespective of the level of transgene expression or end product, due to imbalance of metabolic pools, offering new insight into both anticipated and unanticipated consequences of metabolic engineering.
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Affiliation(s)
- Elise K Pasoreck
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jin Su
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ian M Silverman
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Sager J Gosai
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian D Gregory
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Joshua S Yuan
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA
| | - Henry Daniell
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Albarracín RM, Becher ML, Farran I, Sander VA, Corigliano MG, Yácono ML, Pariani S, López ES, Veramendi J, Clemente M. The fusion of Toxoplasma gondii SAG1 vaccine candidate to Leishmania infantum heat shock protein 83-kDa improves expression levels in tobacco chloroplasts. Biotechnol J 2015; 10:748-59. [PMID: 25823559 DOI: 10.1002/biot.201400742] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 02/12/2015] [Accepted: 03/25/2015] [Indexed: 11/12/2022]
Abstract
Chloroplast transformation technology has emerged as an alternative platform offering many advantages over nuclear transformation. SAG1 is the main surface antigen of the intracellular parasite Toxoplasma gondii and a promising candidate to produce an anti-T. gondii vaccine. The aim of this study was to investigate the expression of SAG1 using chloroplast transformation technology in tobacco plants. In order to improve expression in transplastomic plants, we also expressed the 90-kDa heat shock protein of Leishmania infantum (LiHsp83) as a carrier for the SAG1 antigen. SAG1 protein accumulation in transplastomic plants was approximately 0.1-0.2 μg per gram of fresh weight (FW). Fusion of SAG1 to LiHsp83 significantly increased the level of SAG1 accumulation in tobacco chloroplasts (by up to 500-fold). We also evaluated the functionality of the chLiHsp83-SAG1. Three human seropositive samples reacted with SAG1 expressed in transplastomic chLiHsp83-SAG1 plants. Oral immunization with chLiHsp83-SAG1 elicited a significant reduction of the cyst burden that correlated with an increase of SAG1-specific antibodies. We propose the fusion of foreign proteins to LiHsp83 as a novel strategy to increase the expression level of the recombinant proteins using chloroplast transformation technology, thus addressing one of the current challenges for this approach in antigen protein production.
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Affiliation(s)
- Romina M Albarracín
- Laboratorio de Biotecnología Vegetal, IIB-INTECH, CONICET-UNSAM, Chascomús, Provincia de Buenos Aires, Argentina
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5
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Scotti N, Sannino L, Idoine A, Hamman P, De Stradis A, Giorio P, Maréchal-Drouard L, Bock R, Cardi T. The HIV-1 Pr55 gag polyprotein binds to plastidial membranes and leads to severe impairment of chloroplast biogenesis and seedling lethality in transplastomic tobacco plants. Transgenic Res 2015; 24:319-31. [PMID: 25348481 DOI: 10.1007/s11248-014-9845-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/21/2014] [Indexed: 11/25/2022]
Abstract
Chloroplast genetic engineering has long been recognised as a powerful technology to produce recombinant proteins. To date, however, little attention has been given to the causes of pleiotropic effects reported, in some cases, as consequence of the expression of foreign proteins in transgenic plastids. In this study, we investigated the phenotypic alterations observed in transplastomic tobacco plants accumulating the Pr55(gag) polyprotein of human immunodeficiency virus (HIV-1). The expression of Pr55(gag) at high levels in the tobacco plastome leads to a lethal phenotype of seedlings grown in soil, severe impairment of plastid development and photosynthetic activity, with chloroplasts largely resembling undeveloped proplastids. These alterations are associated to the binding of Pr55(gag) to thylakoids. During particle assembly in HIV-1 infected human cells, the binding of Pr55(gag) to a specific lipid [phosphatidylinositol-(4-5) bisphosphate] in the plasma membrane is mediated by myristoylation at the amino-terminus and the so-called highly basic region (HBR). Surprisingly, the non-myristoylated Pr55(gag) expressed in tobacco plastids was likely able, through the HBR motif, to bind to nonphosphorous glycerogalactolipids or other classes of lipids present in plastidial membranes. Although secondary consequences of disturbed chloroplast biogenesis on expression of nuclear-encoded plastid proteins cannot be ruled out, results of proteomic analyses suggest that their altered accumulation could be due to retrograde control in which chloroplasts relay their status to the nucleus for fine-tuning of gene expression.
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Affiliation(s)
- N Scotti
- CNR-IBBR, Institute of Biosciences and BioResources, National Research Council of Italy, Via Università 133, 80055, Portici, NA, Italy,
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Permyakova NV, Uvarova EA, Deineko EV. State of research in the field of the creation of plant vaccines for veterinary use. RUSSIAN JOURNAL OF PLANT PHYSIOLOGY: A COMPREHENSIVE RUSSIAN JOURNAL ON MODERN PHYTOPHYSIOLOGY 2015; 62:23-38. [PMID: 32214753 PMCID: PMC7089518 DOI: 10.1134/s1021443715010100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Indexed: 06/08/2023]
Abstract
Transgenic plants as an alternative of costly systems of recombinant immunogenic protein expression are the source for the production of cheap and highly efficient biotherapeuticals of new generation, including plant vaccines. In the present review, possibilities of plant system application for the production of recombinant proteins for veterinary use are considered, the history of the "edible vaccine" concept is briefly summarized, advantages and disadvantages of various plant systems for the expression of recombinant immunogenic proteins are discussed. The list of recombinant plant vaccines for veterinary use, which are at different stages of clinical trials, is presented.
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Affiliation(s)
- N. V. Permyakova
- Institute of Cytology and Genetics, Rusian Academy of Sciences, Siberian Branch, pr. Lavrent’eva 10, Novosibirsk, 630090 Russia
| | - E. A. Uvarova
- Institute of Cytology and Genetics, Rusian Academy of Sciences, Siberian Branch, pr. Lavrent’eva 10, Novosibirsk, 630090 Russia
| | - E. V. Deineko
- Institute of Cytology and Genetics, Rusian Academy of Sciences, Siberian Branch, pr. Lavrent’eva 10, Novosibirsk, 630090 Russia
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De Vijlder T, Valkenborg D, Dewaele D, Remmerie N, Laukens K, Witters E. A generic approach for "shotgun" analysis of the soluble proteome of plant cell suspension cultures. J Chromatogr B Analyt Technol Biomed Life Sci 2015; 974:48-56. [PMID: 25463197 DOI: 10.1016/j.jchromb.2014.10.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/13/2014] [Accepted: 10/21/2014] [Indexed: 12/21/2022]
Abstract
Cell suspension cultures from different plant species act as important model systems for studying cellular processes in plant biology and are often used as "green factories" for the production of valuable secondary metabolites and recombinant proteins. While mass spectrometry based proteome analysis techniques are ideally suited to study plant cell metabolism and other fundamental cellular processes from a birds eye perspective, they remain underused in plant studies. We describe a comprehensive sample preparation and multidimensional 'shotgun' proteomics strategy that can be generically applied to plant cell suspension cultures. This strategy was optimized and tested on an Arabidopsis thaliana ecotype Landsberg erecta culture. Furthermore, the implementation of strong cation exchange chromatography as a peptide fractionation step is elaborately tested. Its utility in mass spectrometry based proteome analysis is discussed. Using the presented analytical platform, over 13,000 unique peptides and 2640 proteins could be identified from a single plant cell suspension sample. Finally, the experimental setup is validated using Nicotiana tabacum cv. "Bright Yellow-2" (BY-2) plant cell suspension cultures, thereby demonstrating that the presented analytical platform can also be valuable tool in proteome analysis of non-genomic model systems.
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Affiliation(s)
- Thomas De Vijlder
- Center for Proteomics (CFP), Groenenborgerlaan 171, B-2020 Antwerp, Belgium; Laboratory of Plant Growth and Development, Department of Biology, University of Antwerp, Groenenborgerlaan 171, Antwerp, Belgium.
| | - Dirk Valkenborg
- Center for Proteomics (CFP), Groenenborgerlaan 171, B-2020 Antwerp, Belgium; Vlaamse Instelling voor Technologisch Onderzoek (VITO), Boeretang 200, B-2400 Mol, Belgium; Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Agoralaan 1, B-3590 Diepenbeek, Belgium
| | - Debbie Dewaele
- Biomolecular & Analytical Mass Spectrometry, Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
| | - Noor Remmerie
- Center for Proteomics (CFP), Groenenborgerlaan 171, B-2020 Antwerp, Belgium; Laboratory of Plant Growth and Development, Department of Biology, University of Antwerp, Groenenborgerlaan 171, Antwerp, Belgium
| | - Kris Laukens
- Biomedical Informatics Research Center Antwerp (Biomina), University of Antwerp/Antwerp University Hospital, Wilrijkstraat 10, B-2650 Edegem, Belgium; Advanced Database Research and Modelling, Department of Mathematics and Computer Science, University of Antwerp, Middelheimlaan 1, B-2020 Antwerp, Belgium
| | - Erwin Witters
- Center for Proteomics (CFP), Groenenborgerlaan 171, B-2020 Antwerp, Belgium; Vlaamse Instelling voor Technologisch Onderzoek (VITO), Boeretang 200, B-2400 Mol, Belgium; Laboratory for Ecophysiology, Biochemistry and Toxicology, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
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Kolotilin I, Kaldis A, Pereira EO, Laberge S, Menassa R. Optimization of transplastomic production of hemicellulases in tobacco: effects of expression cassette configuration and tobacco cultivar used as production platform on recombinant protein yields. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:65. [PMID: 23642171 PMCID: PMC3655837 DOI: 10.1186/1754-6834-6-65] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 04/29/2013] [Indexed: 05/21/2023]
Abstract
BACKGROUND Chloroplast transformation in tobacco has been used extensively to produce recombinant proteins and enzymes. Chloroplast expression cassettes can be designed with different configurations of the cis-acting elements that govern foreign gene expression. With the aim to optimize production of recombinant hemicellulases in transplastomic tobacco, we developed a set of cassettes that incorporate elements known to facilitate protein expression in chloroplasts and examined expression and accumulation of a bacterial xylanase XynA. Biomass production is another important factor in achieving sustainable and high-volume production of cellulolytic enzymes. Therefore, we compared productivity of two tobacco cultivars - a low-alkaloid and a high-biomass - as transplastomic expression platforms. RESULTS Four different cassettes expressing XynA produced various mutant phenotypes of the transplastomic plants, affected their growth rate and resulted in different accumulation levels of the XynA enzyme. The most productive cassette was identified and used further to express XynA and two additional fungal xylanases, Xyn10A and Xyn11B, in a high-biomass tobacco cultivar. The high biomass cultivar allowed for a 60% increase in XynA production per plant. Accumulation of the fungal enzymes reached more than 10-fold higher levels than the bacterial enzyme, constituting up to 6% of the total soluble protein in the leaf tissue. Use of a well-characterized translational enhancer with the selected expression cassette revealed inconsistent effects on accumulation of the recombinant xylanases. Additionally, differences in the enzymatic activity of crude plant extracts measured in leaves of different age suggest presence of a specific xylanase inhibitor in the green leaf tissue. CONCLUSION Our results demonstrate the pivotal importance of the expression cassette design and appropriate tobacco cultivar for high-level transplastomic production of recombinant proteins.
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Affiliation(s)
- Igor Kolotilin
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, ON, Canada
| | - Angelo Kaldis
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, ON, Canada
| | - Eridan Orlando Pereira
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, ON, Canada
- Department of Biology, Western University, London, ON, Canada
| | - Serge Laberge
- Soils and Crops Research Development Center, Agriculture and Agri-Food Canada, Québec, QC, Canada
| | - Rima Menassa
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, ON, Canada
- Department of Biology, Western University, London, ON, Canada
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Hanson MR, Gray BN, Ahner BA. Chloroplast transformation for engineering of photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:731-42. [PMID: 23162121 DOI: 10.1093/jxb/ers325] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Many efforts are underway to engineer improvements in photosynthesis to meet the challenges of increasing demands for food and fuel in rapidly changing environmental conditions. Various transgenes have been introduced into either the nuclear or plastid genomes in attempts to increase photosynthetic efficiency. We examine the current knowledge of the critical features that affect levels of expression of plastid transgenes and protein accumulation in transplastomic plants, such as promoters, 5' and 3' untranslated regions, RNA-processing sites, translation signals and amino acid sequences that affect protein turnover. We review the prior attempts to manipulate the properties of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) through plastid transformation. We illustrate how plastid operons could be created for expression of the multiple genes needed to introduce new pathways or enzymes to enhance photosynthetic rates or reduce photorespiration. We describe here the past accomplishments and future prospects for manipulating plant enzymes and pathways to enhance carbon assimilation through plastid transformation.
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Affiliation(s)
- Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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Kazakoff SH, Imelfort M, Edwards D, Koehorst J, Biswas B, Batley J, Scott PT, Gresshoff PM. Capturing the biofuel wellhead and powerhouse: the chloroplast and mitochondrial genomes of the leguminous feedstock tree Pongamia pinnata. PLoS One 2012; 7:e51687. [PMID: 23272141 PMCID: PMC3522722 DOI: 10.1371/journal.pone.0051687] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 11/05/2012] [Indexed: 11/18/2022] Open
Abstract
Pongamia pinnata (syn. Millettia pinnata) is a novel, fast-growing arboreal legume that bears prolific quantities of oil-rich seeds suitable for the production of biodiesel and aviation biofuel. Here, we have used Illumina® 'Second Generation DNA Sequencing (2GS)' and a new short-read de novo assembler, SaSSY, to assemble and annotate the Pongamia chloroplast (152,968 bp; cpDNA) and mitochondrial (425,718 bp; mtDNA) genomes. We also show that SaSSY can be used to accurately assemble 2GS data, by re-assembling the Lotus japonicus cpDNA and in the process assemble its mtDNA (380,861 bp). The Pongamia cpDNA contains 77 unique protein-coding genes and is almost 60% gene-dense. It contains a 50 kb inversion common to other legumes, as well as a novel 6.5 kb inversion that is responsible for the non-disruptive, re-orientation of five protein-coding genes. Additionally, two copies of an inverted repeat firmly place the species outside the subclade of the Fabaceae lacking the inverted repeat. The Pongamia and L. japonicus mtDNA contain just 33 and 31 unique protein-coding genes, respectively, and like other angiosperm mtDNA, have expanded intergenic and multiple repeat regions. Through comparative analysis with Vigna radiata we measured the average synonymous and non-synonymous divergence of all three legume mitochondrial (1.59% and 2.40%, respectively) and chloroplast (8.37% and 8.99%, respectively) protein-coding genes. Finally, we explored the relatedness of Pongamia within the Fabaceae and showed the utility of the organellar genome sequences by mapping transcriptomic data to identify up- and down-regulated stress-responsive gene candidates and confirm in silico predicted RNA editing sites.
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Affiliation(s)
- Stephen H. Kazakoff
- Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Michael Imelfort
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - David Edwards
- Australian Centre for Plant Functional Genomics, The University of Queensland, Brisbane, Queensland, Australia
| | - Jasper Koehorst
- Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Bandana Biswas
- Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Jacqueline Batley
- Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Paul T. Scott
- Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Peter M. Gresshoff
- Australian Research Council Centre of Excellence for Integrative Legume Research, The University of Queensland, Brisbane, Queensland, Australia
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Ceccoli RD, Blanco NE, Segretin ME, Melzer M, Hanke GT, Scheibe R, Hajirezaei MR, Bravo-Almonacid FF, Carrillo N. Flavodoxin displays dose-dependent effects on photosynthesis and stress tolerance when expressed in transgenic tobacco plants. PLANTA 2012; 236:1447-58. [PMID: 22763502 DOI: 10.1007/s00425-012-1695-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 06/16/2012] [Indexed: 05/18/2023]
Abstract
Ferredoxins are iron-sulfur proteins involved in various one-electron transfer pathways. Ferredoxin levels decrease under adverse environmental conditions in photosynthetic organisms. In cyanobacteria, this decline is compensated by induction of flavodoxin, an isofunctional flavoprotein. Flavodoxin is not present in higher plants, but transgenic Nicotiana tabacum lines accumulating Anabaena flavodoxin in plastids display increased tolerance to different sources of environmental stress. As the degree of tolerance correlated with flavodoxin dosage in plastids of nuclear-transformed transgenic tobacco, we prepared plants expressing even higher levels of flavodoxin by direct plastid transformation. A suite of nuclear- and chloroplast-transformed lines expressing a wide range of flavodoxin levels, from 0.3 to 10.8 μmol m(-2), did not exhibit any detectable growth phenotype relative to the wild type. In the absence of stress, the contents of both chlorophyll a and carotenoids, as well as the photosynthetic performance (photosystem II maximum efficiency, photosystem II operating efficiency, electron transport rates and carbon assimilation rates), displayed a moderate increase with flavodoxin concentrations up to 1.3-2.6 μmol flavodoxin m(-2), and then declined to wild-type levels. Stress tolerance, as estimated by the damage inflicted on exposure to the pro-oxidant methyl viologen, also exhibited a bell-shaped response, with a significant, dose-dependent increase in tolerance followed by a drop in the high-expressing lines. The results indicate that optimal photosynthetic performance and stress tolerance were observed at flavodoxin levels comparable to those of endogenous ferredoxin. Further increases in flavodoxin content become detrimental to plant fitness.
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Affiliation(s)
- Romina D Ceccoli
- División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario, Universidad Nacional de Rosario, Suipacha 531, S2002LRK, Rosario, Argentina
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12
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Abstract
Plants have been proved as a novel production platform for a wide range of biologically important compounds such as enzymes, therapeutic proteins, antibiotics, and proteins with immunological properties. In this context, plastid genetic engineering can be potentially used to produce recombinant proteins. However, several challenges still remain to be overcome if the full potential of plastid transformation technology is to be realized. They include the development of plastid transformation systems for species other than tobacco, the expression of transgenes in non-green plastids, the increase of protein accumulation and the appearance of pleiotropic effects. In this paper, we discuss the novel tools recently developed to overcome some limitations of chloroplast transformation.
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Affiliation(s)
- M. Manuela Rigano
- Department of Soil, Plant, Environmental and Animal Production Sciences; University of Naples ‘Federico II’; Portici, Italy
| | - Nunzia Scotti
- CNR-IGV; National Research Council of Italy; Institute of Plant Genetics; Res. Div. Portici; Portici, Italy
| | - Teodoro Cardi
- CNR-IGV; National Research Council of Italy; Institute of Plant Genetics; Res. Div. Portici; Portici, Italy
- CRA-ORT; Agricultural Research Council; Research Centre for Vegetable and Ornamental Crops; Pontecagnano, Italy
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