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Current Opinion in Biotechnology Feb 2018Metabolic pathway engineering by transgene expression from the plastid (chloroplast) genome offers significant attractions, including straightforward multigene... (Review)
Review
Metabolic pathway engineering by transgene expression from the plastid (chloroplast) genome offers significant attractions, including straightforward multigene engineering by pathway expression from operons, high transgene expression levels, and increased transgene containment due to maternal inheritance of plastids in most crops. In addition, it provides direct access to the large and diverse metabolite pools in chloroplasts and non-green plastid types. Here, we review recent progress with extending the toolbox for plastid engineering and highlight selected applications in the area of metabolic engineering, including the combined engineering of nuclear and plastid genomes for the production of artemisinic acid, the direct harness of chloroplast reducing power for the synthesis of dhurrin and the use of an edible host for the production of astaxanthin.
Topics: Antioxidants; Metabolic Engineering; Plants, Genetically Modified; Plastids; Transformation, Genetic; Transgenes
PubMed: 28738208
DOI: 10.1016/j.copbio.2017.07.004 -
Microscopy (Oxford, England) Feb 2019Plastids and mitochondria are thought to have originated from free-living cyanobacterial and alpha-proteobacterial ancestors, respectively, via endosymbiosis. Their...
Plastids and mitochondria are thought to have originated from free-living cyanobacterial and alpha-proteobacterial ancestors, respectively, via endosymbiosis. Their evolutionary origins dictate that these organelles do not multiply de novo but through the division of pre-existing plastids and mitochondria. Over the past three decades, studies have shown that plastid and mitochondrial division are performed by contractile ring-shaped structures, broadly termed the plastid and mitochondrial-division machineries. Interestingly, the division machineries are hybrid forms of the bacterial cell division system and eukaryotic membrane fission system. The structure and function of the plastid and mitochondrial-division machineries are similar to each other, implying that the division machineries evolved in parallel since their establishment in primitive eukaryotes. Compared with our knowledge of their structures, our understanding of the mechanical details of how these division machineries function is still quite limited. Here, we review and compare the structural frameworks of the plastid and mitochondrial-division machineries in both lower and higher eukaryotes. Then, we highlight fundamental issues that need to be resolved to reveal the underlying mechanisms of plastid and mitochondrial division. Finally, we highlight related studies that point to an exciting future for the field.
Topics: Arabidopsis; Cell Division; Chlorophyta; Mitochondria; Plastids; Rhodophyta; Symbiosis
PubMed: 30476140
DOI: 10.1093/jmicro/dfy132 -
Current Opinion in Plant Biology Apr 2021Genetic approaches to modify starch in crops have been limited by our knowledge of starch biosynthesis. Recent advances in Arabidopsis have revealed key genetic... (Review)
Review
Genetic approaches to modify starch in crops have been limited by our knowledge of starch biosynthesis. Recent advances in Arabidopsis have revealed key genetic components determining the size, shape and number of granules in a plastid. This has opened the doors to new discoveries on granule initiation in crop species. In parallel, advances in genomic resources and gene editing technologies allow targeted manipulation of starch biosynthesis genes in isogenic crop backgrounds. Such technologies have been successfully deployed to alter starch composition, and can now be used to modify other starch traits. This will allow the complex relationships between starch structure and physicochemical properties to be elucidated, which will facilitate the rational manipulation of starches in crops.
Topics: Arabidopsis; Crops, Agricultural; Gene Editing; Plastids; Starch
PubMed: 33677239
DOI: 10.1016/j.pbi.2021.102013 -
Plant Physiology Jan 2018Stromules are plastid stroma-filled tubules that increase the surface area of the envelope and extend the reach of the plastid within the plant cell, affecting... (Review)
Review
Stromules are plastid stroma-filled tubules that increase the surface area of the envelope and extend the reach of the plastid within the plant cell, affecting biosynthesis, metabolism, and signaling.
Topics: Cytoplasmic Vesicles; Plastids; Signal Transduction
PubMed: 29097392
DOI: 10.1104/pp.17.01287 -
Plant Biotechnology Journal Feb 2022In the age of synthetic biology, plastid engineering requires a nimble platform to introduce novel synthetic circuits in plants. While effective for integrating...
In the age of synthetic biology, plastid engineering requires a nimble platform to introduce novel synthetic circuits in plants. While effective for integrating relatively small constructs into the plastome, plastid engineering via homologous recombination of transgenes is over 30 years old. Here we show the design-build-test of a novel synthetic genome structure that does not disturb the native plastome: the 'mini-synplastome'. The mini-synplastome was inspired by dinoflagellate plastome organization, which is comprised of numerous minicircles residing in the plastid instead of a single organellar genome molecule. The first mini-synplastome in plants was developed in vitro to meet the following criteria: (i) episomal replication in plastids; (ii) facile cloning; (iii) predictable transgene expression in plastids; (iv) non-integration of vector sequences into the endogenous plastome; and (v) autonomous persistence in the plant over generations in the absence of exogenous selection pressure. Mini-synplastomes are anticipated to revolutionize chloroplast biotechnology, enable facile marker-free plastid engineering, and provide an unparalleled platform for one-step metabolic engineering in plants.
Topics: Genetic Engineering; Metabolic Engineering; Plants; Plastids; Synthetic Biology; Transgenes
PubMed: 34585834
DOI: 10.1111/pbi.13717 -
Cells Oct 2020GUN1 (genomes uncoupled 1), a chloroplast-localized pentatricopeptide repeat (PPR) protein with a C-terminal small mutS-related (SMR) domain, plays a central role in the... (Review)
Review
GUN1 (genomes uncoupled 1), a chloroplast-localized pentatricopeptide repeat (PPR) protein with a C-terminal small mutS-related (SMR) domain, plays a central role in the retrograde communication of chloroplasts with the nucleus. This flow of information is required for the coordinated expression of plastid and nuclear genes, and it is essential for the correct development and functioning of chloroplasts. Multiple genetic and biochemical findings indicate that GUN1 is important for protein homeostasis in the chloroplast; however, a clear and unified view of GUN1's role in the chloroplast is still missing. Recently, GUN1 has been reported to modulate the activity of the nucleus-encoded plastid RNA polymerase (NEP) and modulate editing of plastid RNAs upon activation of retrograde communication, revealing a major role of GUN1 in plastid RNA metabolism. In this opinion article, we discuss the recently identified links between plastid RNA metabolism and retrograde signaling by providing a new and extended concept of GUN1 activity, which integrates the multitude of functional genetic interactions reported over the last decade with its primary role in plastid transcription and transcript editing.
Topics: Gene Expression Regulation, Plant; Plant Proteins; Plastids; Protein Binding; RNA, Chloroplast; Stress, Physiological
PubMed: 33081381
DOI: 10.3390/cells9102307 -
Biochimica Et Biophysica Acta Sep 2015Plastids, such as chloroplasts, are widely distributed endosymbiotic organelles in plants and algae. Apart from their well-known functions in photosynthesis, they have... (Review)
Review
Plastids, such as chloroplasts, are widely distributed endosymbiotic organelles in plants and algae. Apart from their well-known functions in photosynthesis, they have roles in processes as diverse as signal sensing, fruit ripening, and seed development. As most plastid proteins are produced in the cytosol, plastids have developed dedicated translocon machineries for protein import, comprising the TOC (translocon at the outer envelope membrane of chloroplasts) and TIC (translocon at the inner envelope membrane of chloroplasts) complexes. Multiple lines of evidence reveal that protein import via the TOC complex is actively regulated, based on the specific interplay between distinct receptor isoforms and diverse client proteins. In this review, we summarize recent advances in our understanding of protein import regulation, particularly in relation to control by the ubiquitin-proteasome system (UPS), and how such regulation changes plastid development. The diversity of plastid import receptors (and of corresponding preprotein substrates) has a determining role in plastid differentiation and interconversion. The controllable turnover of TOC components by the UPS influences the developmental fate of plastids, which is fundamentally linked to plant development. Understanding the mechanisms by which plastid protein import is controlled is critical to the development of breakthrough approaches to increase the yield, quality and stress tolerance of important crop plants, which are highly dependent on plastid development. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
Topics: Chloroplast Proteins; Plastids; Proteasome Endopeptidase Complex; Protein Transport; Ubiquitin; Ubiquitination
PubMed: 25762164
DOI: 10.1016/j.bbabio.2015.02.017 -
Journal of Plant Physiology Jun 2015Retrograde signaling, defined as the signaling events leading from the plastids to the nucleus, coordinates the expression of plastid and nuclear genes and is crucial... (Review)
Review
Retrograde signaling, defined as the signaling events leading from the plastids to the nucleus, coordinates the expression of plastid and nuclear genes and is crucial for metabolic as well as developmental processes of the plastids. In the recent past, the identification of various components that are involved in the generation and transmission of plastid-originated retrograde signals and the regulation of nuclear gene expression has only provided a glimpse of the plastid retrograde signaling network, which remains poorly understood. The basic assumptions underlying our current understanding of retrograde signaling stayed untouched for many years. Therefore, an attempt has been made in this review article to summarize established facts and recent advances regarding various retrograde signaling pathways derived from different sources, the identification of key elements mediating retrograde signal transduction and also to give an overview of possible signaling molecules that remain to be investigated.
Topics: Cell Nucleus; Models, Biological; Plastids; Regulatory Sequences, Nucleic Acid; Signal Transduction; Transcription Factors
PubMed: 25974370
DOI: 10.1016/j.jplph.2015.04.001 -
Journal of Experimental Botany Nov 2022Plant seeds do not contain differentiated chloroplasts. Upon germination, the seedlings thus need to gain photoautotrophy before storage energies are depleted. This... (Review)
Review
Plant seeds do not contain differentiated chloroplasts. Upon germination, the seedlings thus need to gain photoautotrophy before storage energies are depleted. This requires the coordinated expression of photosynthesis genes encoded in nuclear and plastid genomes. Chloroplast biogenesis needs to be additionally coordinated with the light regulation network that controls seedling development. This coordination is achieved by nucleus to plastid signals called anterograde and plastid to nucleus signals termed retrograde. Retrograde signals sent from plastids during initial chloroplast biogenesis are also called biogenic signals. They have been recognized as highly important for proper chloroplast biogenesis and for seedling development. The molecular nature, transport, targets, and signalling function of biogenic signals are, however, under debate. Several studies disproved the involvement of a number of key components that were at the base of initial models of retrograde signalling. New models now propose major roles for a functional feedback between plastid and cytosolic protein homeostasis in signalling plastid dysfunction as well as the action of dually localized nucleo-plastidic proteins that coordinate chloroplast biogenesis with light-dependent control of seedling development. This review provides a survey of the developments in this research field, summarizes the unsolved questions, highlights several recent advances, and discusses potential new working modes.
Topics: Plastids; Chloroplasts; Genome, Plastid; Chloroplast Proteins; Photosynthesis
PubMed: 36002302
DOI: 10.1093/jxb/erac344 -
Methods in Molecular Biology (Clifton,... 2018Plastids represent a largely diverse group of organelles in plant and algal cells that have several common features but also a broad spectrum of differences in respect... (Review)
Review
Plastids represent a largely diverse group of organelles in plant and algal cells that have several common features but also a broad spectrum of differences in respect of how they look (color, size, and ultrastructure), and what their specific function and molecular composition is. Plastids and their structural and metabolic diversity significantly contribute to the functionality and developmental flexibility of the plant body throughout its lifetime. In addition, to the multiple roles of given plastid types, this diversity is accomplished in some cases by interconversions between different plastids as a consequence of developmental and environmental signals that regulate plastid differentiation and specialization.
Topics: Chloroplasts; Embryophyta; Plant Physiological Phenomena; Plastids
PubMed: 29987714
DOI: 10.1007/978-1-4939-8654-5_4