ORCID Profile
0000-0003-4993-3816
Current Organisation
Western Sydney University - Hawkesbury Campus
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Plant biochemistry | Plant Cell and Molecular Biology | Plant Biology | Genome Structure and Regulation | Agricultural molecular engineering of nucleic acids and proteins | Plant biology | Plant physiology
Publisher: Wiley
Date: 21-12-2016
DOI: 10.1111/PCE.12636
Abstract: C4 photosynthesis evolved multiple times in erse lineages. Most physiological studies comparing C4 plants were not conducted at the low atmospheric CO2 prevailing during their evolution. Here, 24 C4 grasses belonging to three biochemical subtypes [nicotinamide adenine dinucleotide malic enzyme (NAD-ME), phosphoenolpyruvate carboxykinase (PCK) and nicotinamide adenine dinucleotide phosphate malic enzyme (NADP-ME)] and six major evolutionary lineages were grown under ambient (400 μL L(-1) ) and inter-glacial (280 μL L(-1) ) CO2 . We hypothesized that nitrogen-related and water-related physiological traits are associated with subtypes and lineages, respectively. Photosynthetic rate and stomatal conductance were constrained by the shared lineage, while variation in leaf mass per area (LMA), leaf N per area, plant dry mass and plant water use efficiency were influenced by the subtype. Subtype and lineage were equally important for explaining variations in photosynthetic nitrogen use efficiency (PNUE) and photosynthetic water use efficiency (PWUE). CO2 treatment impacted most parameters. Overall, higher LMA and leaf N distinguished the Chloridoideae/NAD-ME group, while NADP-ME and PCK grasses were distinguished by higher PNUE regardless of lineage. Plants were characterized by high photosynthesis and PWUE when grown at ambient CO2 and by high conductance at inter-glacial CO2 . In conclusion, the evolutionary and biochemical ersity among C4 grasses was aligned with discernible leaf physiology, but it remains unknown whether these traits represent ecophysiological adaptation.
Publisher: Oxford University Press (OUP)
Date: 03-02-2008
DOI: 10.1093/JXB/ERM311
Abstract: The inability to assemble Rubisco from any photosynthetic eukaryote within Escherichia coli has h ered structure-function studies of higher plant Rubisco. Precise genetic manipulation of the tobacco chloroplast genome (plastome) by homologous recombination has facilitated the successful production of transplastomic lines that have either mutated the Rubisco large subunit (L) gene, rbcL, or replaced it with foreign variants. Here the capacity of a new tobacco transplastomic line, (cm)trL, to augment future Rubisco engineering studies is demonstrated. Initially the rbcL was replaced with the selectable marker gene, aadA, and an artificial codon-modified (cm)rbcM gene that codes for the structurally novel Rubisco dimer (L(2), approximately 100 kDa) from Rhodosprillum rubrum. To obtain (cm)trL, the aadA was excised by transiently introducing a T-DNA encoding CRE recombinase biolistically. Selection using aadA enabled transplantation of mutated and wild-type tobacco Rubisco genes into the (cm)trL plastome with an efficiency that was 3- to 10-fold higher than comparable transformations into wild-type tobacco. Transformants producing the re-introduced form I tobacco Rubisco variants (hexadecamers comprising eight L and eight small subunits, approximately 520 kDa) were identified by non-denaturing PAGE with fully segregated homoplasmic lines (where no L(2) Rubisco was produced) obtained within 6-9 weeks after transformation which enabled their Rubisco kinetics to be quickly examined. Here the usefulness of (cm)trL in more readily examining the production, folding, and assembly capabilities of both mutated tobacco and foreign form I Rubisco subunits in tobacco plastids is discussed, and the feasibility of quickly assessing the kinetic properties of those that functionally assemble is demonstrated.
Publisher: Oxford University Press (OUP)
Date: 20-02-2009
Abstract: Manipulation of Rubisco within higher plants is complicated by the different genomic locations of the large (L rbcL) and small (S RbcS) subunit genes. Although rbcL can be accurately modified by plastome transformation, directed genetic manipulation of the multiple nuclear-encoded RbcS genes is more challenging. Here we demonstrate the viability of linking the S and L subunits of tobacco (Nicotiana tabacum) Rubisco using a flexible 40-amino acid tether. By replacing the rbcL in tobacco plastids with an artificial gene coding for a S40L fusion peptide, we found that the fusions readily assemble into catalytic (S40L)8 and (S40L)16 oligomers that are devoid of unlinked S subunits. While there was little or no change in CO2/O2 specificity or carboxylation rate of the Rubisco oligomers, their K ms for CO2 and O2 were reduced 10% to 20% and 45%, respectively. In young maturing leaves of the plastome transformants (called ANtS40L), the S40L-Rubisco levels were approximately 20% that of wild-type controls despite turnover of the S40L-Rubisco oligomers being only slightly enhanced relative to wild type. The reduced Rubisco content in ANtS40L leaves is partly attributed to problems with folding and assembly of the S40L peptides in tobacco plastids that relegate approximately 30% to 50% of the S40L pool to the insoluble protein fraction. Leaf CO2-assimilation rates in ANtS40L at varying pCO2 corresponded with the kinetics and reduced content of the Rubisco oligomers. This fusion strategy provides a novel platform to begin simultaneously engineering Rubisco L and S subunits in tobacco plastids.
Publisher: Oxford University Press (OUP)
Date: 15-03-2018
DOI: 10.1104/PP.18.00023
Publisher: Oxford University Press (OUP)
Date: 31-10-2017
DOI: 10.1104/PP.17.01346
Publisher: Oxford University Press (OUP)
Date: 19-06-2008
DOI: 10.1093/JXB/ERM373
Abstract: The activation of Rubisco in vivo requires the presence of the regulatory protein Rubisco activase. This enzyme facilitates the release of sugar phosphate inhibitors from Rubisco catalytic sites thereby influencing carbamylation. T(1) progeny of transgenic Flaveria bidentis (a C(4) dicot) containing genetically reduced levels of Rubisco activase were used to explore the role of the enzyme in C(4) photosynthesis at high temperature. A range of T(1) progeny was screened at 25 degrees C and 40 degrees C for Rubisco activase content, photosynthetic rate, Rubisco carbamylation, and photosynthetic metabolite pools. The small isoform of F. bidentis activase was expressed and purified from E. coli and used to quantify leaf activase content. In wild-type F. bidentis, the activase monomer content was 10.6+/-0.8 micromol m(-2) (447+/-36 mg m(-2)) compared to a Rubisco site content of 14.2+/-0.8 micromol m(-2). CO(2) assimilation rates and Rubisco carbamylation declined at both 25 degrees C and 40 degrees C when the Rubisco activase content dropped below 3 mumol m(-2) (125 mg m(-2)), with the status of Rubisco carbamylation at an activase content greater than this threshold value being 44+/-5% at 40 degrees C compared to 81+/-2% at 25 degrees C. When the CO(2) assimilation rate was reduced, ribulose-1,5-bisphosphate and aspartate pools increased whereas 3-phosphoglycerate and phosphoenol pyruvate levels decreased, demonstrating an interconnectivity of the C(3) and C(4) metabolites pools. It is concluded that during short-term treatment at 40 degrees C, Rubisco activase content is not the only factor modulating Rubisco carbamylation during C(4) photosynthesis.
Publisher: Wiley
Date: 19-06-2018
DOI: 10.1111/GCB.14330
Abstract: Climate is an important factor limiting tree distributions and adaptation to different thermal environments may influence how tree populations respond to climate warming. Given the current rate of warming, it has been hypothesized that tree populations in warmer, more thermally stable climates may have limited capacity to respond physiologically to warming compared to populations from cooler, more seasonal climates. We determined in a controlled environment how several provenances of widely distributed Eucalyptus tereticornis and E. grandis adjusted their photosynthetic capacity to +3.5°C warming along their native distribution range (~16-38°S) and whether climate of seed origin of the provenances influenced their response to different growth temperatures. We also tested how temperature optima (T
Publisher: Oxford University Press (OUP)
Date: 18-02-2020
DOI: 10.1093/JXB/ERAA077
Abstract: Photosynthesis has become a major trait of interest for cereal yield improvement as breeders appear to have reached the theoretical genetic limit for harvest index, the mass of grain as a proportion of crop biomass. Yield improvements afforded by the adoption of green revolution dwarfing genes to wheat and rice are becoming exhausted, and improvements in biomass and radiation use efficiency are now sought in these crops. Exploring genetic ersity in photosynthesis is now possible using high-throughput techniques, and low-cost genotyping facilitates discovery of the genetic architecture underlying this variation. Photosynthetic traits have been shown to be highly heritable, and significant variation is present for these traits in available germplasm. This offers hope that breeding for improved photosynthesis and radiation use efficiency in cereal crops is tractable and a useful shorter term adjunct to genetic and genome engineering to boost yield potential.
Publisher: Oxford University Press (OUP)
Date: 02-02-2017
DOI: 10.1104/PP.16.01893
Publisher: Oxford University Press (OUP)
Date: 22-11-2023
DOI: 10.1093/JXB/ERAC458
Abstract: Rubisco catalysis is complex and includes an activation step through the formation of a carbamate at the conserved active site lysine residue and the formation of a highly reactive enediol that is the key to its catalytic reaction. The formation of this enediol is both the basis of its success and its Achilles’ heel, creating imperfections to its catalytic efficiency. While Rubisco originally evolved in an atmosphere of high CO2, the earth’s multiple oxidation events provided challenges to Rubisco through the fixation of O2 that competes with CO2 at the active site. Numerous catalytic screens across the Rubisco superfamily have identified significant variation in catalytic properties that have been linked to large and small subunit sequences. Despite this, we still have a rudimentary understanding of Rubisco’s catalytic mechanism and how the evolution of kinetic properties has occurred. This review identifies the lysine base that functions both as an activator and a proton abstractor to create the enediol as a key to understanding how Rubisco may optimize its kinetic properties. The ways in which Rubisco and its partners have overcome catalytic and activation imperfections and thrived in a world of high O2, low CO2, and variable climatic regimes is remarkable.
Publisher: eLife Sciences Publications, Ltd
Date: 17-10-2021
Publisher: Wiley
Date: 20-10-2023
DOI: 10.1111/PCE.14453
Abstract: Photosynthetic manipulation provides new opportunities for enhancing crop yield. However, understanding and quantifying the importance of in idual and multiple manipulations on the seasonal biomass growth and yield performance of target crops across variable production environments is limited. Using a state‐of‐the‐art cross‐scale model in the APSIM platform we predicted the impact of altering photosynthesis on the enzyme‐limited ( A c ) and electron transport‐limited ( A j ) rates, seasonal dynamics in canopy photosynthesis, biomass growth, and yield formation via large multiyear‐by‐location crop growth simulations. A broad list of promising strategies to improve photosynthesis for C 3 wheat and C 4 sorghum were simulated. In the top decile of seasonal outcomes, yield gains were predicted to be modest, ranging between 0% and 8%, depending on the manipulation and crop type. We report how photosynthetic enhancement can affect the timing and severity of water and nitrogen stress on the growing crop, resulting in nonintuitive seasonal crop dynamics and yield outcomes. We predicted that strategies enhancing A c alone generate more consistent but smaller yield gains across all water and nitrogen environments, A j enhancement alone generates larger gains but is undesirable in more marginal environments. Large increases in both A c and A j generate the highest gains across all environments. Yield outcomes of the tested manipulation strategies were predicted and compared for realistic Australian wheat and sorghum production. This study uniquely unpacks complex cross‐scale interactions between photosynthesis and seasonal crop dynamics and improves understanding and quantification of the potential impact of photosynthesis traits (or lack of it) for crop improvement research.
Publisher: Oxford University Press (OUP)
Date: 10-04-2014
DOI: 10.1093/JXB/ERU155
Publisher: Oxford University Press (OUP)
Date: 04-2014
DOI: 10.1093/JXB/ERU130
Publisher: Humana Press
Date: 2014
DOI: 10.1007/978-1-62703-995-6_15
Abstract: The assimilation of CO2 within chloroplasts is catalyzed by the bi-functional enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, Rubisco. Within higher plants the Rubisco large subunit gene, rbcL, is encoded in the plastid genome, while the Rubisco small subunit gene, RbcS is coded in the nucleus by a multi-gene family. Rubisco is considered a poor catalyst due to its slow turnover rate and its additional fixation of O2 that can result in wasteful loss of carbon through the energy requiring photorespiratory cycle. Improving the carboxylation efficiency and CO2/O2 selectivity of Rubisco within higher plants has been a long-term goal which has been greatly advanced in recent times using plastid transformation techniques. Here we present experimental methodologies for efficiently engineering Rubisco in the plastids of a tobacco master-line and analyzing leaf Rubisco content.
Publisher: Oxford University Press (OUP)
Date: 11-03-2022
DOI: 10.1093/JXB/ERAC081
Abstract: Improvement of photosynthetic traits in crops to increase yield potential and crop resilience has recently become a major breeding target. Synthetic biology and genetic technologies offer unparalleled opportunities to create new genetics for photosynthetic traits driven by existing fundamental knowledge. However, large ‘gene bank’ collections of germplasm comprising historical collections of crop species and their relatives offer a wealth of opportunities to find novel allelic variation in the key steps of photosynthesis, to identify new mechanisms and to accelerate genetic progress in crop breeding programmes. Here we explore the available genetic resources in food and fibre crops, strategies to selectively target allelic variation in genes underpinning key photosynthetic processes, and deployment of this variation via gene editing in modern elite material.
Publisher: Oxford University Press (OUP)
Date: 27-04-2016
DOI: 10.1093/JXB/ERW154
Publisher: Wiley
Date: 09-12-2017
DOI: 10.1111/NPH.14351
Abstract: The uncertainty of future climate change is placing pressure on cropping systems to continue to provide stable increases in productive yields. To mitigate future climates and the increasing threats against global food security, new solutions to manipulate photosynthesis are required. This review explores the current efforts available to improve carbon assimilation within plant chloroplasts by engineering Rubisco, which catalyzes the rate‐limiting step of CO 2 fixation. Fixation of CO 2 and subsequent cycling of 3‐phosphoglycerate through the Calvin cycle provides the necessary carbohydrate building blocks for maintaining plant growth and yield, but has to compete with Rubisco oxygenation, which results in photorespiration that is energetically wasteful for plants. Engineering improvements in Rubisco is a complex challenge and requires an understanding of chloroplast gene regulatory pathways, and the intricate nature of Rubisco catalysis and biogenesis, to transplant more efficient forms of Rubisco into crops. In recent times, major advances in Rubisco engineering have been achieved through improvement of our knowledge of Rubisco synthesis and assembly, and identifying amino acid catalytic switches in the L‐subunit responsible for improvements in catalysis. Improving the capacity of CO 2 fixation in crops such as rice will require further advances in chloroplast bioengineering and Rubisco biogenesis. Contents Summary 494 I. Introduction 495 II. Prokaryotic ancestry of chloroplasts influences gene regulatory mechanisms 496 III. The target enzyme of CO 2 fixation within chloroplasts – Rubisco 496 IV. Oxygenation of RuBP leads to photorespiration and h ers C 3 plant photosynthesis 499 V. Exploring nature for improved Rubisco 499 VI. Prospects for improving rice photosynthesis by altering Rubisco catalysis 501 VII. Engineering CO 2 assimilation in higher plants by plastid transformation 501 VIII. Direct bioengineering of Rubisco in higher plants 502 IX. The next challenges that need to be met for Rubisco engineering 505 X. Conclusions 506 Acknowledgements 507 References 507
Publisher: Wiley
Date: 20-12-2020
DOI: 10.1111/PBI.13306
Publisher: Oxford University Press (OUP)
Date: 08-03-2023
DOI: 10.1093/JXB/ERAD076
Abstract: In the developing seeds of all higher plants, filial cells are symplastically isolated from the maternal tissue supplying photosynthate to the reproductive structure. Photoassimilates must be transported apoplastically, crossing several membrane barriers, a process facilitated by sugar transporters. Sugars Will Eventually be Exported Transporters (SWEETs) have been proposed to play a crucial role in apoplastic sugar transport during phloem unloading and the post-phloem pathway in sink tissues. Evidence for this is presented here for developing seeds of the C4 model grass Setaria viridis. Using immunolocalization, SvSWEET4 was detected in various maternal and filial tissues within the seed along the sugar transport pathway, in the vascular parenchyma of the pedicel, and in the xylem parenchyma of the stem. Expression of SvSWEET4a in Xenopus laevis oocytes indicated that it functions as a high-capacity glucose and sucrose transporter. Carbohydrate and transcriptional profiling of Setaria seed heads showed that there were some developmental shifts in hexose and sucrose content and consistent expression of SvSWEET4 homologues. Collectively, these results provide evidence for the involvement of SWEETs in the apoplastic transport pathway of sink tissues and allow a pathway for post-phloem sugar transport into the seed to be proposed.
Publisher: Oxford University Press (OUP)
Date: 04-10-2016
DOI: 10.1093/JXB/ERW357
Publisher: Proceedings of the National Academy of Sciences
Date: 17-08-2011
Abstract: Improving global yields of important agricultural crops is a complex challenge. Enhancing yield and resource use by engineering improvements to photosynthetic carbon assimilation is one potential solution. During the last 40 million years C 4 photosynthesis has evolved multiple times, enabling plants to evade the catalytic inadequacies of the CO 2 -fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). Compared with their C 3 ancestors, C 4 plants combine a faster rubisco with a biochemical CO 2 -concentrating mechanism, enabling more efficient use of water and nitrogen and enhanced yield. Here we show the versatility of plastome manipulation in tobacco for identifying sequences in C 4 -rubisco that can be transplanted into C 3 -rubisco to improve carboxylation rate ( V C ). Using transplastomic tobacco lines expressing native and mutated rubisco large subunits (L-subunits) from Flaveria pringlei (C 3 ), Flaveria floridana (C 3 -C 4 ), and Flaveria bidentis (C 4 ), we reveal that Met-309-Ile substitutions in the L-subunit act as a catalytic switch between C 4 ( 309 Ile faster V C , lower CO 2 affinity) and C 3 ( 309 Met slower V C , higher CO 2 affinity) catalysis. Application of this transplastomic system permits further identification of other structural solutions selected by nature that can increase rubisco V C in C 3 crops. Coengineering a catalytically faster C 3 rubisco and a CO 2 -concentrating mechanism within C 3 crop species could enhance their efficiency in resource use and yield.
Publisher: Cold Spring Harbor Laboratory
Date: 09-12-2011
DOI: 10.1261/RNA.2336611
Abstract: Post-transcriptional regulation in the chloroplast is exerted by nucleus-encoded ribonucleases and RNA-binding proteins. One of these ribonucleases is RNR1, a 3′-to-5′ exoribonuclease of the RNase II family. We have previously shown that Arabidopsis rnr1 -null mutants exhibit specific abnormalities in the expression of the rRNA operon, including the accumulation of precursor 23S, 16S, and 4.5S species and a concomitant decrease in the mature species. 5S rRNA transcripts, however, accumulate to a very low level in both precursor and mature forms, suggesting that they are unstable in the rnr1 background. Here we demonstrate that rnr1 plants overaccumulate an antisense RNA, AS5, that is complementary to the 5S rRNA, its intergenic spacer, and the downstream trnR gene, which encodes tRNA Arg , raising the possibility that AS5 destabilizes 5S rRNA or its precursor and/or blocks rRNA maturation. To investigate this, we used an in vitro system that supports 5S rRNA and trnR processing. We show that AS5 inhibits 5S rRNA maturation from a 5S- trnR precursor, and shorter versions of AS5 demonstrate that inhibition requires intergenic sequences. To test whether the sense and antisense RNAs form double-stranded regions in vitro, treatment with the single-strand-specific mung bean nuclease was used. These results suggest that 5S–AS5 duplexes interfere with a sense-strand secondary structure near the endonucleolytic cleavage site downstream from the 5S rRNA coding region. We hypothesize that these duplexes are degraded by a dsRNA-specific ribonuclease in vivo, contributing to the 5S rRNA deficiency observed in rnr1 .
Publisher: Wiley
Date: 20-03-2017
DOI: 10.1111/NPH.14514
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.PBI.2016.04.002
Abstract: By operating a CO2 concentrating mechanism, C4-photosynthesis offers highly successful solutions to remedy the inefficiency of the CO2-fixing enzyme Rubisco. C4-plant Rubisco has characteristically evolved faster carboxylation rates with low CO2 affinity. Owing to high CO2 concentrations in bundle sheath chloroplasts, faster Rubisco enhances resource use efficiency in C4 plants by reducing the energy and carbon costs associated with photorespiration and lowering the nitrogen investment in Rubisco. Here, we show that C4-Rubisco from some NADP-ME species, such as maize, are also of potential benefit to C3-photosynthesis under current and future atmospheric CO2 pressures. Realizing this bioengineering endeavour necessitates improved understanding of the biogenesis requirements and catalytic variability of C4-Rubisco, as well as the development of transformation capabilities to engineer Rubisco in a wider variety of food and fibre crops.
Publisher: eLife Sciences Publications, Ltd
Date: 29-11-2021
DOI: 10.7554/ELIFE.70095
Abstract: A fundamental limitation of photosynthetic carbon fixation is the availability of CO 2 . In C 4 plants, primary carboxylation occurs in mesophyll cytosol, and little is known about the role of CO 2 diffusion in facilitating C 4 photosynthesis. We have examined the expression, localization, and functional role of selected plasma membrane intrinsic aquaporins (PIPs) from Setaria italica (foxtail millet) and discovered that SiPIP2 is CO 2 -permeable. When ectopically expressed in mesophyll cells of Setaria viridis (green foxtail), SiPIP2 was localized to the plasma membrane and caused no marked changes in leaf biochemistry. Gas exchange and C 18 O 16 O discrimination measurements revealed that targeted expression of SiPIP2 enhanced the conductance to CO 2 diffusion from the intercellular airspace to the mesophyll cytosol. Our results demonstrate that mesophyll conductance limits C 4 photosynthesis at low p CO 2 and that SiPIP2 is a functional CO 2 permeable aquaporin that can improve CO 2 diffusion at the airspace/mesophyll interface and enhance C 4 photosynthesis.
Publisher: Wiley
Date: 06-07-2019
DOI: 10.1111/NPH.15920
Abstract: C
Publisher: Oxford University Press (OUP)
Date: 09-11-2008
Abstract: Plastomic replacement of the tobacco (Nicotiana tabacum) Rubisco large subunit gene (rbcL) with that from sunflower (Helianthus annuus rbcLS) produced tobaccoRst transformants that produced a hybrid Rubisco consisting of sunflower large and tobacco small subunits (LsSt). The tobaccoRst plants required CO2 (0.5% v/v) supplementation to grow autotrophically from seed despite the substrate saturated carboxylation rate, K m, for CO2 and CO2/O2 selectivity of the LsSt enzyme mirroring the kinetically equivalent tobacco and sunflower Rubiscos. Consequently, at the onset of exponential growth when the source strength and leaf LsSt content were sufficient, tobaccoRst plants grew to maturity without CO2 supplementation. When grown under a high pCO2, the tobaccoRst seedlings grew slower than tobacco and exhibited unique growth phenotypes: Juvenile plants formed clusters of 10 to 20 structurally simple oblanceolate leaves, developed multiple apical meristems, and the mature leaves displayed marginal curling and dimpling. Depending on developmental stage, the LsSt content in tobaccoRst leaves was 4- to 7-fold less than tobacco, and gas exchange coupled with chlorophyll fluorescence showed that at 2 mbar pCO2 and growth illumination CO2 assimilation in mature tobaccoRst leaves remained limited by Rubisco activity and its rate (approximately 11 μmol m−2 s−1) was half that of tobacco controls. 35S-methionine labeling showed the stability of assembled LsSt was similar to tobacco Rubisco and measurements of light transient CO2 assimilation rates showed LsSt was adequately regulated by tobacco Rubisco activase. We conclude limitations to tobaccoRst growth primarily stem from reduced rbcLS mRNA levels and the translation and/or assembly of sunflower large with the tobacco small subunits that restricted LsSt synthesis.
Publisher: Elsevier
Date: 2005
Publisher: Wiley
Date: 09-07-2014
DOI: 10.1111/PCE.12386
Publisher: Oxford University Press (OUP)
Date: 06-08-2013
DOI: 10.1093/NAR/GKT640
Publisher: Wiley
Date: 16-05-2022
DOI: 10.1002/SAE2.12014
Abstract: Conventional breeding techniques have been integral to the development of many agronomically important traits in numerous crops. The adoption of modern biotechnology approaches further advanced and refined trait development and introduction beyond the scope possible through conventional breeding. However, crop yields continue to be challenged by abiotic and biotic factors that require the development of traits that are more genetically complex than can be addressed through conventional breeding or traditional genetic engineering. Therefore, more advanced trait development approaches are required to maintain and improve yields and production efficiency, especially as climate change accelerates the incidence of biotic and abiotic challenges to food and fibre crops. Synthetic biology (SynBio) encompasses approaches that design and construct new biological elements (e.g., enzymes, genetic circuits, cells) or redesign existing biological systems to build new and improved functions. SynBio ‘upgrades’ the potential of genetic engineering, which involves the transfer of single genes from one organism to another. This technology can enable the introduction of multiple genes in a single transgenic event, either derived from a foreign organism or synthetically generated. It can also enable the assembly of novel genomes from the ground up from a set of standardised genetic parts, which can then be transferred into the target cell or organism. New opportunities to advance breeding applications through exploiting SynBio technology include the introduction of new genes of known function, artificially creating genetic variation, topical applications of small RNAs as pesticides and potentially speeding up the production of new cultivars with elite traits. This review will draw upon case studies to demonstrate the potential application of SynBio to improve crop productivity and resistance to various challenges. Here, we outline specific solutions to challenges including fungal diseases, insect pests, heat and drought stress and nutrient acquisition in a range of important crops using the SynBio toolkit.
Publisher: Springer Science and Business Media LLC
Date: 09-12-2009
DOI: 10.1007/S11103-008-9436-Z
Abstract: The chloroplast protein CSP41a both binds and cleaves RNA, particularly in stem-loops, and has been found associated with ribosomes. A related protein, CSP41b, co-purifies with CSP41a, ribosomes, and the plastid-encoded RNA polymerase. Here we show that Arabidopsis CSP41a and CSP41b interact in vivo, and that a csp41b null mutant becomes depleted of CSP41a in mature leaves, correlating with a pale green phenotype and reduced accumulation of the ATP synthase and cytochrome b ( 6 )/f complexes. RNA gel blot analyses revealed up to four-fold decreases in accumulation for some chloroplast RNAs, which run-on experiments suggested could tentatively be ascribed to decreased transcription. Depletion of both CSP41a and CSP41b triggered a promoter switch whereby atpBE became predominately transcribed from its nucleus-encoded polymerase promoter as opposed to its plastid-encoded polymerase promoter. Together with published proteomic data, this suggests that CSP41a and/or CSP41b enhances transcription by the plastid-encoded polymerase. Gradient analysis of rRNAs in the mutant suggest a defect in polysome assembly or stability, suggesting that CSP41a and/or CSP41b, which are not present in polysomal fractions, stabilize ribosome assembly intermediates. Although psbA and rbcL mRNAs are normally polysome-associated in the mutant, petD-containing RNAs have diminished association, perhaps accounting for reduced accumulation of its respective multimeric complex. In conclusion, our data suggest that CSP41a and CSP41b stimulate both transcription and translation in the chloroplast.
Publisher: Cold Spring Harbor Laboratory
Date: 27-10-2011
Abstract: Ribonuclease J is an essential enzyme, and the Bacillus subtilis ortholog possesses both endoribonuclease and 5′ → 3′ exoribonuclease activities. Chloroplasts also contain RNase J, which has been postulated to participate, as both an exo- and endonuclease, in the maturation of polycistronic mRNAs. Here we have examined recombinant Arabidopsis RNase J and found both 5′ → 3′ exoribonuclease and endonucleolytic activities. Virus-induced gene silencing was used to reduce RNase J expression in Arabidopsis and Nicotiana benthamiana , leading to chlorosis but surprisingly few disruptions in the cleavage of polycistronic rRNA and mRNA precursors. In contrast, antisense RNAs accumulated massively, suggesting that the failure of chloroplast RNA polymerase to terminate effectively leads to extensive symmetric transcription products that are normally eliminated by RNase J. Mung bean nuclease digestion and polysome analysis revealed that this antisense RNA forms duplexes with sense strand transcripts and prevents their translation. We conclude that a major role of chloroplast RNase J is RNA surveillance to prevent overaccumulation of antisense RNA, which would otherwise exert deleterious effects on chloroplast gene expression.
Publisher: Oxford University Press (OUP)
Date: 09-07-2020
DOI: 10.1105/TPC.20.00288
Publisher: Oxford University Press (OUP)
Date: 05-04-2018
DOI: 10.1093/JXB/ERY129
Publisher: Oxford University Press (OUP)
Date: 07-01-2017
DOI: 10.1093/JXB/ERW484
Publisher: Elsevier BV
Date: 02-2007
Publisher: Oxford University Press (OUP)
Date: 09-2017
DOI: 10.1093/JXB/ERX350
Publisher: Springer Science and Business Media LLC
Date: 28-11-2016
Abstract: Enhancing the catalytic properties of the CO
Publisher: Springer Science and Business Media LLC
Date: 14-09-2020
Publisher: Oxford University Press (OUP)
Date: 29-04-2016
DOI: 10.1093/JXB/ERW163
Publisher: Authorea, Inc.
Date: 07-08-2023
DOI: 10.22541/AU.169140993.39140230/V1
Abstract: Leaf gas exchange measurements provide an important tool for inferring a plant’s photosynthetic biochemistry. In most cases, the responses of photosynthetic CO assimilation to variable intercellular CO concentrations ( A / C response curves) are used to model the maximum rate of carboxylation by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, V ) and the rate of electron transport at a given photosynthetically active radiation (PAR J ). The standard Farquhar-Von Caemmerer-Berry model is typically used with default parameters of Rubisco kinetic values and mesophyll conductance to CO ( g ) derived from tobacco that impairs analytical reliability across species. To study this, here we measured the temperature responses of key in vitro Rubisco catalytic properties and g in cotton ( Gossypium hirsutum cv. Sicot 71) and derived V and J ( J at 2000 µmol m s PAR) from cotton A / C curves incrementally measured at 15°C to 40°C using cotton and tobacco parameters with our new automated fitting R package ‘OptiFitACi’. When applied to cotton, the tobacco parameters produced unrealistic J : V ratio of at 25°C, two- to three-fold higher estimates of V , approximately 50% higher estimates of J and more variable estimates of V and J , compared to model parameterisation with cotton-derived values. We determined that errors arise when using a g of 0.23 mol m s bar or below and Rubisco CO -affinities under ambient O ( K ) outside 461 µbar to 627 µbar to model A / C responses in cotton. We show how the multi- A / C modelling capabilities of ‘OptiFitACi’ serves as a robust, user-friendly extension of ‘plantecophys’ by providing simplified temperature-sensitivity and species-specificity parameterisation capabilities to enable higher accuracy estimates of V and J .
Start Date: 2023
End Date: 12-2025
Amount: $482,066.00
Funder: Australian Research Council
View Funded ActivityStart Date: 09-2013
End Date: 09-2016
Amount: $374,000.00
Funder: Australian Research Council
View Funded Activity