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Lao XL, Meng Y, Wu J, Wen J, Nie ZL. Plastid genomes provide insights into the phylogeny and chloroplast evolution of the paper daisy tribe Gnaphalieae (Asteraceae). Gene 2024; 901:148177. [PMID: 38242378 DOI: 10.1016/j.gene.2024.148177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/03/2024] [Accepted: 01/16/2024] [Indexed: 01/21/2024]
Abstract
Chloroplast genomes, as an essential source of phylogenetic information, are increasingly utilized in the evolutionary study of angiosperms. Gnaphalieae is a medium-sized tribe of the sunflower family of Asteraceae, with about 2,100 species in 178 genera distributed in temperate habitats worldwide. There has been considerable progress in our understanding of their phylogenetic evolution using both nuclear and chloroplast sequences, but no focus on chloroplast genomic data. In this study, we performed sequencing, assembly, and annotation of 16 representative chloroplast genomes from all the major lineages of Gnaphalieae. Our results showed that the plastomes exhibited a typical circular tetrad structure with similar genomic structure gene content. But there were differences in genome size, SSRs, and codon usage within the tribe. Phylogenetic analysis revealed Relhania clade is the earliest diverged lineages with the Lasiopogon clade and the Gnaphalium s.s. clade diverged subsequently. The core group includes FLAG clade sister to the HAP and Australasian group. Compared with the outgroup species, chloroplast genome size of the FLAG clade is much reduced whereas those of Australasian, HAP, Gnaphalium s.s., Lasiopogon and Relhania clades are relatively expanded. Insertions and deletions in the intergenic regions associated with repetitive sequence variations are supposed to be the main factor leading to length variations in the chloroplast genomes of Gnaphalieae. The comparative analyses of chloroplast genomes would provide useful implications into understanding the taxonomic and evolutionary history of Gnaphalieae.
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Affiliation(s)
- Xiao-Lin Lao
- College of Biology and Environmental Sciences, Jishou University, Jishou, Hunan 416000, China
| | - Ying Meng
- College of Biology and Environmental Sciences, Jishou University, Jishou, Hunan 416000, China
| | - Jue Wu
- College of Biology and Environmental Sciences, Jishou University, Jishou, Hunan 416000, China
| | - Jun Wen
- Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, USA
| | - Ze-Long Nie
- College of Biology and Environmental Sciences, Jishou University, Jishou, Hunan 416000, China.
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2
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Herbst J, Li QQ, De Veylder L. Mechanistic insights into DNA damage recognition and checkpoint control in plants. NATURE PLANTS 2024; 10:539-550. [PMID: 38503962 DOI: 10.1038/s41477-024-01652-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 02/18/2024] [Indexed: 03/21/2024]
Abstract
The plant DNA damage response (DDR) pathway safeguards genomic integrity by rapid recognition and repair of DNA lesions that, if unrepaired, may cause genome instability. Most frequently, DNA repair goes hand in hand with a transient cell cycle arrest, which allows cells to repair the DNA lesions before engaging in a mitotic event, but consequently also affects plant growth and yield. Through the identification of DDR proteins and cell cycle regulators that react to DNA double-strand breaks or replication defects, it has become clear that these proteins and regulators form highly interconnected networks. These networks operate at both the transcriptional and post-transcriptional levels and include liquid-liquid phase separation and epigenetic mechanisms. Strikingly, whereas the upstream DDR sensors and signalling components are well conserved across eukaryotes, some of the more downstream effectors are diverged in plants, probably to suit unique lifestyle features. Additionally, DDR components display functional diversity across ancient plant species, dicots and monocots. The observed resistance of DDR mutants towards aluminium toxicity, phosphate limitation and seed ageing indicates that gaining knowledge about the plant DDR may offer solutions to combat the effects of climate change and the associated risk for food security.
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Affiliation(s)
- Josephine Herbst
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
- Center for Plant Systems Biology, VIB, Gent, Belgium
| | - Qian-Qian Li
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
- Center for Plant Systems Biology, VIB, Gent, Belgium
| | - Lieven De Veylder
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium.
- Center for Plant Systems Biology, VIB, Gent, Belgium.
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3
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Tripathi D, Oldenburg DJ, Bendich AJ. Ribonucleotide and R-Loop Damage in Plastid DNA and Mitochondrial DNA during Maize Development. PLANTS (BASEL, SWITZERLAND) 2023; 12:3161. [PMID: 37687407 PMCID: PMC10489836 DOI: 10.3390/plants12173161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023]
Abstract
Although the temporary presence of ribonucleotides in DNA is normal, their persistence represents a form of DNA damage. Here, we assess such damage and damage defense to DNA in plastids and mitochondria of maize. Shoot development proceeds from meristematic, non-pigmented cells containing proplastids and promitochondria at the leaf base to non-dividing green cells in the leaf blade containing mature organelles. The organellar DNAs (orgDNAs) become fragmented during this transition. Previously, orgDNA damage and damage defense of two types, oxidative and glycation, was described in maize, and now a third type, ribonucleotide damage, is reported. We hypothesized that ribonucleotide damage changes during leaf development and could contribute to the demise of orgDNAs. The levels of ribonucleotides and R-loops in orgDNAs and of RNase H proteins in organelles were measured throughout leaf development and in leaves grown in light and dark conditions. The data reveal that ribonucleotide damage to orgDNAs increased by about 2- to 5-fold during normal maize development from basal meristem to green leaf and when leaves were grown in normal light conditions compared to in the dark. During this developmental transition, the levels of the major agent of defense, RNase H, declined. The decline in organellar genome integrity during maize development may be attributed to oxidative, glycation, and ribonucleotide damages that are not repaired.
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Affiliation(s)
| | | | - Arnold J. Bendich
- Department of Biology, University of Washington, Seattle, WA 98195, USA; (D.T.); (D.J.O.)
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4
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Tripathi D, Oldenburg DJ, Bendich AJ. Oxidative and Glycation Damage to Mitochondrial DNA and Plastid DNA during Plant Development. Antioxidants (Basel) 2023; 12:antiox12040891. [PMID: 37107266 PMCID: PMC10135910 DOI: 10.3390/antiox12040891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 04/08/2023] Open
Abstract
Oxidative damage to plant proteins, lipids, and DNA caused by reactive oxygen species (ROS) has long been studied. The damaging effects of reactive carbonyl groups (glycation damage) to plant proteins and lipids have also been extensively studied, but only recently has glycation damage to the DNA in plant mitochondria and plastids been reported. Here, we review data on organellar DNA maintenance after damage from ROS and glycation. Our focus is maize, where tissues representing the entire range of leaf development are readily obtained, from slow-growing cells in the basal meristem, containing immature organelles with pristine DNA, to fast-growing leaf cells, containing mature organelles with highly-fragmented DNA. The relative contributions to DNA damage from oxidation and glycation are not known. However, the changing patterns of damage and damage-defense during leaf development indicate tight coordination of responses to oxidation and glycation events. Future efforts should be directed at the mechanism by which this coordination is achieved.
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Affiliation(s)
- Diwaker Tripathi
- Department of Biology, University of Washington, Seattle, WA 98195, USA
| | | | - Arnold J. Bendich
- Department of Biology, University of Washington, Seattle, WA 98195, USA
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5
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Ren Y, Zhu S. Nitric oxide promotes energy metabolism and protects mitochondrial DNA in peaches during cold storage. FRONTIERS IN PLANT SCIENCE 2022; 13:970303. [PMID: 36275543 PMCID: PMC9582448 DOI: 10.3389/fpls.2022.970303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 09/16/2022] [Indexed: 05/30/2023]
Abstract
The mitochondria are important organelles related to energy metabolism and are susceptible to oxidative damage. In this experiment, peaches (Prunus persica) were treated with distilled water (as the control), 15 μmol L-1 of nitric oxide (NO), and 20 μmol L-1 of carboxy-PTIO (NO scavenger). The changes in mitochondrial physiological indicators, energy metabolism process, and mitochondrial DNA (mtDNA) damage and repair were quantified. Compared with the control, NO treatment reduced mitochondrial oxygen consumption and the reactive oxygen species content, increased mitochondrial respiration control rate, and promoted energy metabolism by influencing the activities of citrate synthase, aconitase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase in the tricarboxylic acid cycle and ATPase activity in peach mitochondria. NO treatment also maintained the relative copy number of mtDNA and the relative amplification of long PCR in peaches, decreased the level of 8-hydroxy-2 deoxyguanosine, and upregulated the expression of PpOGG1, PpAPE1, and PpLIG1. These results indicated that exogenous NO treatment (15 μmol L-1) could reduce mtDNA oxidative damage, maintain mtDNA molecular integrity, and inhibit mtDNA copy number reduction by reducing the reactive oxygen species content, thereby promoting mitochondrial energy metabolism and prolonging the storage life of peaches at low temperatures.
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Santana I, Jeon SJ, Kim HI, Islam MR, Castillo C, Garcia GFH, Newkirk GM, Giraldo JP. Targeted Carbon Nanostructures for Chemical and Gene Delivery to Plant Chloroplasts. ACS NANO 2022; 16:12156-12173. [PMID: 35943045 DOI: 10.1021/acsnano.2c02714] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Nanotechnology approaches for improving the delivery efficiency of chemicals and molecular cargoes in plants through plant biorecognition mechanisms remain relatively unexplored. We developed targeted carbon-based nanomaterials as tools for precise chemical delivery (carbon dots, CDs) and gene delivery platforms (single-walled carbon nanotubes, SWCNTs) to chloroplasts, key organelles involved in efforts to improve plant photosynthesis, assimilation of nutrients, and delivery of agrochemicals. A biorecognition approach of coating the nanomaterials with a rationally designed chloroplast targeting peptide improved the delivery of CDs with molecular baskets (TP-β-CD) for delivery of agrochemicals and of plasmid DNA coated SWCNT (TP-pATV1-SWCNT) from 47% to 70% and from 39% to 57% of chloroplasts in leaves, respectively. Plants treated with TP-β-CD (20 mg/L) and TP-pATV1-SWCNT (2 mg/L) had a low percentage of dead cells, 6% and 8%, respectively, similar to controls without nanoparticles, and no permanent cell and chloroplast membrane damage after 5 days of exposure. However, targeted nanomaterials transiently increased leaf H2O2 (0.3225 μmol gFW-1) above control plant levels (0.03441 μmol gFW-1) but within the normal range reported in land plants. The increase in leaf H2O2 levels was associated with oxidative damage in whole plant cell DNA, a transient effect on chloroplast DNA, and a decrease in leaf chlorophyll content (-17%) and carbon assimilation rates at saturation light levels (-32%) with no impact on photosystem II quantum yield. This work provides targeted delivery approaches for carbon-based nanomaterials mediated by biorecognition and a comprehensive understanding of their impact on plant cell and molecular biology for engineering safer and efficient agrochemical and biomolecule delivery tools.
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Affiliation(s)
- Israel Santana
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California 92521, United States
| | - Su-Ji Jeon
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California 92521, United States
| | - Hye-In Kim
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California 92521, United States
| | - Md Reyazul Islam
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California 92521, United States
| | - Christopher Castillo
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California 92521, United States
| | - Gail F H Garcia
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California 92521, United States
| | - Gregory M Newkirk
- Department of Microbiology and Plant Pathology, University of California-Riverside, Riverside, California 92521, United States
| | - Juan Pablo Giraldo
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, California 92521, United States
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Sheikh-Assadi M, Naderi R, Kafi M, Fatahi R, Salami SA, Shariati V. Complete chloroplast genome of Lilium ledebourii (Baker) Boiss and its comparative analysis: lights into selective pressure and adaptive evolution. Sci Rep 2022; 12:9375. [PMID: 35672390 PMCID: PMC9174193 DOI: 10.1038/s41598-022-13449-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 05/24/2022] [Indexed: 01/02/2023] Open
Abstract
Lilium ledebourii (Baker) Boiss is a rare species, which exhibits valuable traits. However, before its genetic diversity and evolutionary were uncovered, its wild resources were jeopardized. Moreover, some ambiguities in phylogenetic relationships of this genus remain unresolved. Therefore, obtaining the whole chloroplast sequences of L. ledebourii and its comparative analysis along with other Lilium species is crucial and pivotal to understanding the evolution of this genus as well as the genetic populations. A multi-scale genome-level analysis, especially selection pressure, was conducted. Detailed third‑generation sequencing and analysis revealed a whole chloroplast genome of 151,884 bp, with an ordinary quadripartite and protected structure comprising 37.0% GC. Overall, 113 different genes were recognized in the chloroplast genome, consisting of 30 distinct tRNA genes, four distinct ribosomal RNAs genes, and 79 unique protein-encoding genes. Here, 3234 SSRs and 2053 complex repeats were identified, and a comprehensive analysis was performed for IR expansion and contraction, and codon usage bias. Moreover, genome-wide sliding window analysis revealed the variability of rpl32-trnL-ccsA, petD-rpoA, ycf1, psbI-trnS-trnG, rps15-ycf1, trnR, trnT-trnL, and trnP-psaJ-rpl33 were higher among the 48 Lilium cp genomes, displaying higher variability of nucleotide in SC regions. Following 1128 pairwise comparisons, ndhB, psbJ, psbZ, and ycf2 exhibit zero synonymous substitution, revealing divergence or genetic restriction. Furthermore, out of 78 protein-coding genes, we found that accD and rpl36 under positive selection: however, at the entire-chloroplast protein scale, the Lilium species have gone through a purifying selection. Also, a new phylogenetic tree for Lilium was rebuilt, and we believe that the Lilium classification is clearer than before. The genetic resources provided here will aid future studies in species identification, population genetics, and Lilium conservation.
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Affiliation(s)
- Morteza Sheikh-Assadi
- Department of Horticultural Science, Faculty of Agricultural Science and Engineering, University of Tehran, Karaj, Iran.
| | - Roohangiz Naderi
- Department of Horticultural Science, Faculty of Agricultural Science and Engineering, University of Tehran, Karaj, Iran.
| | - Mohsen Kafi
- Department of Horticultural Science, Faculty of Agricultural Science and Engineering, University of Tehran, Karaj, Iran
| | - Reza Fatahi
- Department of Horticultural Science, Faculty of Agricultural Science and Engineering, University of Tehran, Karaj, Iran
| | - Seyed Alireza Salami
- Department of Horticultural Science, Faculty of Agricultural Science and Engineering, University of Tehran, Karaj, Iran
| | - Vahid Shariati
- NIGEB Genome Center, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
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8
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Fischer A, Dotzek J, Walther D, Greiner S. Graph-based models of the Oenothera mitochondrial genome capture the enormous complexity of higher plant mitochondrial DNA organization. NAR Genom Bioinform 2022; 4:lqac027. [PMID: 35372837 PMCID: PMC8969700 DOI: 10.1093/nargab/lqac027] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 03/02/2022] [Accepted: 03/09/2022] [Indexed: 12/26/2022] Open
Abstract
Plant mitochondrial genomes display an enormous structural complexity, as recombining repeat-pairs lead to the generation of various sub-genomic molecules, rendering these genomes extremely challenging to assemble. We present a novel bioinformatic data-processing pipeline called SAGBAC (Semi-Automated Graph-Based Assembly Curator) that identifies recombinogenic repeat-pairs and reconstructs plant mitochondrial genomes. SAGBAC processes assembly outputs and applies our novel ISEIS (Iterative Sequence Ends Identity Search) algorithm to obtain a graph-based visualization. We applied this approach to three mitochondrial genomes of evening primrose (Oenothera), a plant genus used for cytoplasmic genetics studies. All identified repeat pairs were found to be flanked by two alternative and unique sequence-contigs defining so-called 'double forks', resulting in four possible contig-repeat-contig combinations for each repeat pair. Based on the inferred structural models, the stoichiometry of the different contig-repeat-contig combinations was analyzed using Illumina mate-pair and PacBio RSII data. This uncovered a remarkable structural diversity of the three closely related mitochondrial genomes, as well as substantial phylogenetic variation of the underlying repeats. Our model allows predicting all recombination events and, thus, all possible sub-genomes. In future work, the proposed methodology may prove useful for the investigation of the sub-genome organization and dynamics in different tissues and at various developmental stages.
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Affiliation(s)
- Axel Fischer
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Jana Dotzek
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Dirk Walther
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Stephan Greiner
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
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9
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Tripathi D, Oldenburg DJ, Bendich AJ. Analysis of the Plastid Genome Sequence During Maize Seedling Development. Front Genet 2022; 13:870115. [PMID: 35559017 PMCID: PMC9086435 DOI: 10.3389/fgene.2022.870115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Shoot development in maize progresses from small, non-pigmented meristematic cells to expanded cells in the green leaf. During this transition, large plastid DNA (ptDNA) molecules in proplastids become fragmented in the photosynthetically-active chloroplasts. The genome sequences were determined for ptDNA obtained from Zea mays B73 plastids isolated from four tissues: base of the stalk (the meristem region); fully-developed first green leaf; first three leaves from light-grown seedlings; and first three leaves from dark-grown (etiolated) seedlings. These genome sequences were then compared to the Z. mays B73 plastid reference genome sequence that was previously obtained from green leaves. The assembled plastid genome was identical among these four tissues to the reference genome. Furthermore, there was no difference among these tissues in the sequence at and around the previously documented 27 RNA editing sites. There were, however, more sequence variants (insertions/deletions and single-nucleotide polymorphisms) for leaves grown in the dark than in the light. These variants were tightly clustered into two areas within the inverted repeat regions of the plastid genome. We propose a model for how these variant clusters could be generated by replication-transcription conflict.
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Affiliation(s)
- Diwaker Tripathi
- Department of Biology, University of Washington, Seattle, WA, United States
| | - Delene J Oldenburg
- Department of Biology, University of Washington, Seattle, WA, United States
| | - Arnold J Bendich
- Department of Biology, University of Washington, Seattle, WA, United States
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10
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Glycation damage to organelles and their DNA increases during maize seedling development. Sci Rep 2022; 12:2688. [PMID: 35177666 PMCID: PMC8854438 DOI: 10.1038/s41598-022-06454-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/31/2022] [Indexed: 11/17/2022] Open
Abstract
Shoot development in maize begins when meristematic, non-pigmented cells at leaf base stop dividing and proceeds toward the expanded green cells of the leaf blade. During this transition, promitochondria and proplastids develop into mature organelles and their DNA becomes fragmented. Changes in glycation damage during organelle development were measured for protein and DNA, as well as the glycating agent methyl glyoxal and the glycation-defense protein DJ-1 (known as Park7 in humans). Maize seedlings were grown under normal, non-stressful conditions. Nonetheless, we found that glycation damage, as well as defenses against glycation, follow the same developmental pattern we found previously for reactive oxygen species (ROS): as damage increases, damage-defense measures decrease. In addition, light-grown leaves had more glycation and less DJ-1 compared to dark-grown leaves. The demise of maize organellar DNA during development may therefore be attributed to both oxidative and glycation damage that is not repaired. The coordination between oxidative and glycation damage, as well as damage-response from the nucleus is also discussed.
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Chen J, Wang L, Jin X, Wan J, Zhang L, Je BI, Zhao K, Kong F, Huang J, Tian M. Oryza sativa ObgC1 Acts as a Key Regulator of DNA Replication and Ribosome Biogenesis in Chloroplast Nucleoids. RICE (NEW YORK, N.Y.) 2021; 14:65. [PMID: 34251486 PMCID: PMC8275814 DOI: 10.1186/s12284-021-00498-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 05/30/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND The Spo0B-associated GTP-binding protein (Obg) GTPase, has diverse and important functions in bacteria, including morphological development, DNA replication and ribosome maturation. Homologs of the Bacillus subtilis Obg have been also found in chloroplast of Oryza sativa, but their primary roles remain unknown. RESULTS We clarify that OsObgC1 is a functional homolog of AtObgC. The mutant obgc1-d1 exhibited hypersensitivity to the DNA replication inhibitor hydroxyurea. Quantitative PCR results showed that the ratio of chloroplast DNA to nuclear DNA in the mutants was higher than that of the wild-type plants. After DAPI staining, OsObgC1 mutants showed abnormal nucleoid architectures. The specific punctate staining pattern of OsObgC1-GFP signal suggests that this protein localizes to the chloroplast nucleoids. Furthermore, loss-of-function mutation in OsObgC1 led to a severe suppression of protein biosynthesis by affecting plastid rRNA processing. It was also demonstrated through rRNA profiling that plastid rRNA processing was decreased in obgc1-d mutants, which resulted in impaired ribosome biogenesis. The sucrose density gradient profiles revealed a defective chloroplast ribosome maturation of obgc1-d1 mutants. CONCLUSION Our findings here indicate that the OsObgC1 retains the evolutionarily biological conserved roles of prokaryotic Obg, which acts as a signaling hub that regulates DNA replication and ribosome biogenesis in chloroplast nucleoids.
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Affiliation(s)
- Ji Chen
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
- Division of Applied Life Sciences (BK21+), Graduate School of Gyeongsang National University, Jinju, 660-701, Republic of Korea
| | - Li Wang
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Xiaowan Jin
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Jian Wan
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Lang Zhang
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Byoung Il Je
- College of Ecology and Environment, Chengdu University of Technology, Chengdu, 61005, China
| | - Ke Zhao
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Fanlei Kong
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Jin Huang
- Division of Applied Life Sciences (BK21+), Graduate School of Gyeongsang National University, Jinju, 660-701, Republic of Korea.
- College of Ecology and Environment, Chengdu University of Technology, Chengdu, 61005, China.
| | - Mengliang Tian
- Institute for New Rural Development, Sichuan Agricultural University, Yaan, 625000, China.
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12
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Lyko P, Wicke S. Genomic reconfiguration in parasitic plants involves considerable gene losses alongside global genome size inflation and gene births. PLANT PHYSIOLOGY 2021; 186:1412-1423. [PMID: 33909907 PMCID: PMC8260112 DOI: 10.1093/plphys/kiab192] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/13/2021] [Indexed: 05/02/2023]
Abstract
Parasitic plant genomes and transcriptomes reveal numerous genetic innovations, the functional-evolutionary relevance and roles of which open unprecedented research avenues.
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Affiliation(s)
- Peter Lyko
- Institute for Biology, Humboldt-University of Berlin, Germany
| | - Susann Wicke
- Institute for Biology, Humboldt-University of Berlin, Germany
- Author for communication:
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13
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Ferguson JN, Tidy AC, Murchie EH, Wilson ZA. The potential of resilient carbon dynamics for stabilizing crop reproductive development and productivity during heat stress. PLANT, CELL & ENVIRONMENT 2021; 44:2066-2089. [PMID: 33538010 DOI: 10.1111/pce.14015] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 05/20/2023]
Abstract
Impaired carbon metabolism and reproductive development constrain crop productivity during heat stress. Reproductive development is energy intensive, and its requirement for respiratory substrates rises as associated metabolism increases with temperature. Understanding how these processes are integrated and the extent to which they contribute to the maintenance of yield during and following periods of elevated temperatures is important for developing climate-resilient crops. Recent studies are beginning to demonstrate links between processes underlying carbon dynamics and reproduction during heat stress, consequently a summation of research that has been reported thus far and an evaluation of purported associations are needed to guide and stimulate future research. To this end, we review recent studies relating to source-sink dynamics, non-foliar photosynthesis and net carbon gain as pivotal in understanding how to improve reproductive development and crop productivity during heat stress. Rapid and precise phenotyping during narrow phenological windows will be important for understanding mechanisms underlying these processes, thus we discuss the development of relevant high-throughput phenotyping approaches that will allow for more informed decision-making regarding future crop improvement.
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Affiliation(s)
- John N Ferguson
- Division of Plant & Crop Science, University of Nottingham, Leicestershire, UK
- Future Food Beacon of Excellence, School of Biosciences, University of Nottingham, Leicestershire, UK
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Alison C Tidy
- Division of Plant & Crop Science, University of Nottingham, Leicestershire, UK
| | - Erik H Murchie
- Division of Plant & Crop Science, University of Nottingham, Leicestershire, UK
| | - Zoe A Wilson
- Division of Plant & Crop Science, University of Nottingham, Leicestershire, UK
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14
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Huang R, Xie X, Li F, Tian E, Chao Z. Chloroplast genomes of two Mediterranean Bupleurum species and the phylogenetic relationship inferred from combined analysis with East Asian species. PLANTA 2021; 253:81. [PMID: 33765202 DOI: 10.1007/s00425-021-03602-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
The chloroplast genomes of Mediterranean Bupleurum species are reported for the first time. Phylogenetic analysis supports the species as a basal clade of Bupleurum with divergence time at 35.40 Ma. Bupleurum is one of the most species-rich genus with high medicinal value in Apiaceae. Although infrageneric classifications of Bupleurum have been the subject of numerous studies, it still remains controversial. Chloroplast genome information will prove essential in advancing our understanding on phylogenetic study. Here we report cp genomes of two woody Bupleurum species (Bupleurum gibraltaricum and B. fruticosum) endemic to Mediterranean. The complete cp genomes of the two species were 157,303 and 157,391 bp in size, respectively. They encoded 114 unique genes including 30 tRNA genes, 4 rRNA genes and 80 protein coding genes. Genome structure, distributions of SDRs and SSRs, gene content exhibited similarities among Bupleurum species. High variable hotspots were detected in eight intergenic spacers and four genes. Most of genes were under purifying selection with two exceptions: atpF and clpP. The phylogenetic analysis based on 80 coding genes revealed that the genus was divided into 2 distinct clades corresponding to the 2 subgenera (subg. Penninervia, subg. Bupleurum) with divergence time at the end of collision of India with Eurasia. Most species diversified mainly during the later period of uplift of Qinghai-Tibetan Plateau. The cp genomes of the two Bupleurum species can be significant complementary to insights into the cp genome characteristics of this genus. The comparative chloroplast genomes and phylogenetic analysis advances our understanding of the evolution of cp genomes and phylogeny in Bupleurum.
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Affiliation(s)
- Rong Huang
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, 510515, China
| | - Xuena Xie
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, 510515, China
| | - Fang Li
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, 510515, China
| | - Enwei Tian
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, 510515, China
| | - Zhi Chao
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, 510515, China.
- Guangdong Provincial Key Laboratory of Chinese Medicine Pharmaceutics, Guangzhou, 510515, China.
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Duan S, Hu L, Dong B, Jin HL, Wang HB. Signaling from Plastid Genome Stability Modulates Endoreplication and Cell Cycle during Plant Development. Cell Rep 2021; 32:108019. [PMID: 32783941 DOI: 10.1016/j.celrep.2020.108019] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/08/2020] [Accepted: 07/20/2020] [Indexed: 01/10/2023] Open
Abstract
Plastid-nucleus genome coordination is crucial for plastid activity, but the mechanisms remain unclear. By treating Arabidopsis plants with the organellar genome-damaging agent ciprofloxacin, we found that plastid genome instability can alter endoreplication and the cell cycle. Similar results are observed in the plastid genome instability mutants of reca1why1why3. Cell division and embryo development are disturbed in the reca1why1why3 mutant. Notably, SMR5 and SMR7 genes, which encode cell-cycle kinase inhibitors, are upregulated in plastid genome instability plants, and the mutation of SMR7 can restore the endoreplication and growth phenotype of reca1why1why3 plants. Furthermore, we establish that the DNA damage response transcription factor SOG1 mediates the alteration of endoreplication and cell cycle triggered by plastid genome instability. Finally, we demonstrate that reactive oxygen species produced in plastids are important for plastid-nucleus genome coordination. Our findings uncover a molecular mechanism for the coordination of plastid and nuclear genomes during plant growth and development.
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Affiliation(s)
- Sujuan Duan
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, People's Republic of China; Institute of Medical Plant Physiology and Ecology, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, 510006 Guangzhou, People's Republic of China
| | - Lili Hu
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, People's Republic of China
| | - Beibei Dong
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, People's Republic of China
| | - Hong-Lei Jin
- Institute of Medical Plant Physiology and Ecology, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, 510006 Guangzhou, People's Republic of China.
| | - Hong-Bin Wang
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, People's Republic of China; Institute of Medical Plant Physiology and Ecology, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, 510006 Guangzhou, People's Republic of China.
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Gajecka M, Marzec M, Chmielewska B, Jelonek J, Zbieszczyk J, Szarejko I. Changes in plastid biogenesis leading to the formation of albino regenerants in barley microspore culture. BMC PLANT BIOLOGY 2021; 21:22. [PMID: 33413097 PMCID: PMC7792217 DOI: 10.1186/s12870-020-02755-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 11/24/2020] [Indexed: 06/06/2023]
Abstract
BACKGROUND Microspore embryogenesis is potentially the most effective method of obtaining doubled haploids (DH) which are utilized in breeding programs to accelerate production of new cultivars. However, the regeneration of albino plants significantly limits the exploitation of androgenesis for DH production in cereals. Despite many efforts, the precise mechanisms leading to development of albino regenerants have not yet been elucidated. The objective of this study was to reveal the genotype-dependent molecular differences in chloroplast differentiation that lead to the formation of green and albino regenerants in microspore culture of barley. RESULTS We performed a detailed analysis of plastid differentiation at successive stages of androgenesis in two barley cultivars, 'Jersey' and 'Mercada' that differed in their ability to produce green regenerants. We demonstrated the lack of transition from the NEP-dependent to PEP-dependent transcription in plastids of cv. 'Mercada' that produced mostly albino regenerants in microspore culture. The failed NEP-to-PEP transition was associated with the lack of activity of Sig2 gene encoding a sigma factor necessary for transcription of plastid rRNA genes. A very low level of 16S and 23S rRNA transcripts and impaired plastid translation machinery resulted in the inhibition of photomorphogenesis in regenerating embryos and albino regenerants. Furthermore, the plastids present in differentiating 'Mercada' embryos contained a low number of plastome copies whose replication was not always completed. Contrary to 'Mercada', cv. 'Jersey' that produced 90% green regenerants, showed the high activity of PEP polymerase, the highly increased expression of Sig2, plastid rRNAs and tRNAGlu, which indicated the NEP inhibition. The increased expression of GLKs genes encoding transcription factors required for induction of photomorphogenesis was also observed in 'Jersey' regenerants. CONCLUSIONS Proplastids present in microspore-derived embryos of albino-producing genotypes did not pass the early checkpoints of their development that are required for induction of further light-dependent differentiation of chloroplasts. The failed activation of plastid-encoded RNA polymerase during differentiation of embryos was associated with the genotype-dependent inability to regenerate green plants in barley microspore culture. The better understanding of molecular mechanisms underlying formation of albino regenerants may be helpful in overcoming the problem of albinism in cereal androgenesis.
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Affiliation(s)
- Monika Gajecka
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, Jagiellonska 28, Katowice, 40-032, Poland
| | - Marek Marzec
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, Jagiellonska 28, Katowice, 40-032, Poland
| | - Beata Chmielewska
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, Jagiellonska 28, Katowice, 40-032, Poland
| | - Janusz Jelonek
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, Jagiellonska 28, Katowice, 40-032, Poland
| | - Justyna Zbieszczyk
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, Jagiellonska 28, Katowice, 40-032, Poland
| | - Iwona Szarejko
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia, Jagiellonska 28, Katowice, 40-032, Poland.
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17
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Lim LWK, Chung HH, Hussain H. Organellar genome copy number variations and integrity across different organs, growth stages, phenotypes and main localities of sago palm (Metroxylon sagu Rottboll) in Sarawak, Malaysia. GENE REPORTS 2020. [DOI: 10.1016/j.genrep.2020.100808] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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18
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Freudenthal JA, Pfaff S, Terhoeven N, Korte A, Ankenbrand MJ, Förster F. A systematic comparison of chloroplast genome assembly tools. Genome Biol 2020; 21:254. [PMID: 32988404 PMCID: PMC7520963 DOI: 10.1186/s13059-020-02153-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/22/2020] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Chloroplasts are intracellular organelles that enable plants to conduct photosynthesis. They arose through the symbiotic integration of a prokaryotic cell into an eukaryotic host cell and still contain their own genomes with distinct genomic information. Plastid genomes accommodate essential genes and are regularly utilized in biotechnology or phylogenetics. Different assemblers that are able to assess the plastid genome have been developed. These assemblers often use data of whole genome sequencing experiments, which usually contain reads from the complete chloroplast genome. RESULTS The performance of different assembly tools has never been systematically compared. Here, we present a benchmark of seven chloroplast assembly tools, capable of succeeding in more than 60% of known real data sets. Our results show significant differences between the tested assemblers in terms of generating whole chloroplast genome sequences and computational requirements. The examination of 105 data sets from species with unknown plastid genomes leads to the assembly of 20 novel chloroplast genomes. CONCLUSIONS We create docker images for each tested tool that are freely available for the scientific community and ensure reproducibility of the analyses. These containers allow the analysis and screening of data sets for chloroplast genomes using standard computational infrastructure. Thus, large scale screening for chloroplasts within genomic sequencing data is feasible.
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Affiliation(s)
- Jan A. Freudenthal
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074 Germany
- AnaLife Data Science, Wiesengrund 16, Würzburg, 97295 Waldbrunn Germany
| | - Simon Pfaff
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074 Germany
- Department of Bioinformatics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, 97074 Germany
| | - Niklas Terhoeven
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074 Germany
- AnaLife Data Science, Wiesengrund 16, Würzburg, 97295 Waldbrunn Germany
| | - Arthur Korte
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074 Germany
| | - Markus J. Ankenbrand
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074 Germany
- AnaLife Data Science, Wiesengrund 16, Würzburg, 97295 Waldbrunn Germany
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Josef-Schneider-Str. 2, Würzburg, 97080 Germany
| | - Frank Förster
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074 Germany
- Department of Bioinformatics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, 97074 Germany
- Fraunhofer IME-BR, Ohlebergsweg 12, Gießen, 35392 Germany
- Bioinformatics Core Facility of the University of Gießen, Heinrich-Buff-Ring 58, Gießen, 35392 Germany
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19
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Freudenthal JA, Pfaff S, Terhoeven N, Korte A, Ankenbrand MJ, Förster F. A systematic comparison of chloroplast genome assembly tools. Genome Biol 2020; 21:254. [PMID: 32988404 DOI: 10.1101/665869] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 08/22/2020] [Indexed: 05/21/2023] Open
Abstract
BACKGROUND Chloroplasts are intracellular organelles that enable plants to conduct photosynthesis. They arose through the symbiotic integration of a prokaryotic cell into an eukaryotic host cell and still contain their own genomes with distinct genomic information. Plastid genomes accommodate essential genes and are regularly utilized in biotechnology or phylogenetics. Different assemblers that are able to assess the plastid genome have been developed. These assemblers often use data of whole genome sequencing experiments, which usually contain reads from the complete chloroplast genome. RESULTS The performance of different assembly tools has never been systematically compared. Here, we present a benchmark of seven chloroplast assembly tools, capable of succeeding in more than 60% of known real data sets. Our results show significant differences between the tested assemblers in terms of generating whole chloroplast genome sequences and computational requirements. The examination of 105 data sets from species with unknown plastid genomes leads to the assembly of 20 novel chloroplast genomes. CONCLUSIONS We create docker images for each tested tool that are freely available for the scientific community and ensure reproducibility of the analyses. These containers allow the analysis and screening of data sets for chloroplast genomes using standard computational infrastructure. Thus, large scale screening for chloroplasts within genomic sequencing data is feasible.
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Affiliation(s)
- Jan A Freudenthal
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074, Germany
| | - Simon Pfaff
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074, Germany
- AnaLife Data Science, Wiesengrund 16, Würzburg, 97295 Waldbrunn, Germany
- Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Josef-Schneider-Str. 2, Würzburg, 97080, Germany
| | - Niklas Terhoeven
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074, Germany
- AnaLife Data Science, Wiesengrund 16, Würzburg, 97295 Waldbrunn, Germany
| | - Arthur Korte
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074, Germany
- Department of Bioinformatics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, 97074, Germany
| | - Markus J Ankenbrand
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074, Germany
- AnaLife Data Science, Wiesengrund 16, Würzburg, 97295 Waldbrunn, Germany
| | - Frank Förster
- Center for Computational and Theoretical Biology, University of Würzburg, Campus Hubland Nord, Würzburg, 97074, Germany.
- Department of Bioinformatics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, 97074, Germany.
- Fraunhofer IME-BR, Ohlebergsweg 12, Gießen, 35392, Germany.
- Bioinformatics Core Facility of the University of Gießen, Heinrich-Buff-Ring 58, Gießen, 35392, Germany.
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20
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Wu Z, Liao R, Yang T, Dong X, Lan D, Qin R, Liu H. Analysis of six chloroplast genomes provides insight into the evolution of Chrysosplenium (Saxifragaceae). BMC Genomics 2020; 21:621. [PMID: 32912155 PMCID: PMC7488271 DOI: 10.1186/s12864-020-07045-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/01/2020] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Chrysosplenium L. (Saxifragaceae) is a genus of plants widely distributed in Northern Hemisphere and usually found in moist, shaded valleys and mountain slopes. This genus is ideal for studying plant adaptation to low light conditions. Although some progress has been made in the systematics and biogeography of Chrysosplenium, its chloroplast genome evolution remains to be investigated. RESULTS To fill this gap, we sequenced the chloroplast genomes of six Chrysosplenium species and analyzed their genome structure, GC content, and nucleotide diversity. Moreover, we performed a phylogenetic analysis and calculated non-synonymous (Ka) /synonymous (Ks) substitution ratios using the combined protein-coding genes of 29 species within Saxifragales and two additional species as outgroups, as well as a pair-wise estimation for each gene within Chrysosplenium. Compared with the outgroups in Saxifragaceae, the six Chrysosplenium chloroplast genomes had lower GC contents; they also had conserved boundary regions and gene contents, as only the rpl32 gene was lost in four of the Chrysosplenium chloroplast genomes. Phylogenetic analyses suggested that the Chrysosplenium separated to two major clades (the opposite group and the alternate group). The selection pressure estimation (Ka/Ks ratios) of genes in the Chrysosplenium species showed that matK and ycf2 were subjected to positive selection. CONCLUSION This study provides genetic resources for exploring the phylogeny of Chrysosplenium and sheds light on plant adaptation to low light conditions. The lower average GC content and the lacking gene of rpl32 indicated selective pressure in their unique habitats. Different from results previously reported, our selective pressure estimation suggested that the genes related to photosynthesis (such as ycf2) were under positive selection at sites in the coding region.
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Affiliation(s)
- Zhihua Wu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, Key Laboratory of State Ethnic Affairs Commission for Biological Technology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, Hubei, China
| | - Rui Liao
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, Key Laboratory of State Ethnic Affairs Commission for Biological Technology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, Hubei, China
| | - Tiange Yang
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, Key Laboratory of State Ethnic Affairs Commission for Biological Technology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, Hubei, China
| | - Xiang Dong
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, Hubei, China
| | - Deqing Lan
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, Key Laboratory of State Ethnic Affairs Commission for Biological Technology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, Hubei, China
| | - Rui Qin
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, Key Laboratory of State Ethnic Affairs Commission for Biological Technology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, Hubei, China
| | - Hong Liu
- Hubei Provincial Key Laboratory for Protection and Application of Special Plant Germplasm in Wuling Area of China, Key Laboratory of State Ethnic Affairs Commission for Biological Technology, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, Hubei, China.
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21
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Sugimoto H, Hirano M, Tanaka H, Tanaka T, Kitagawa-Yogo R, Muramoto N, Mitsukawa N. Plastid-targeted forms of restriction endonucleases enhance the plastid genome rearrangement rate and trigger the reorganization of its genomic architecture. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:1042-1057. [PMID: 31925982 DOI: 10.1111/tpj.14687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/25/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
Plant cells have acquired chloroplasts (plastids) with a unique genome (ptDNA), which developed during the evolution of endosymbiosis. The gene content and genome structure of ptDNAs in land plants are considerably stable, although those of algal ptDNAs are highly varied. Plant cells seem, therefore, to be intolerant of any structural or organizational changes in the ptDNA. Genome rearrangement functions as a driver of genomic evolutionary divergence. Here, we aimed to create various types of rearrangements in the ptDNA of Arabidopsis genomes using plastid-targeted forms of restriction endonucleases (pREs). Arabidopsis plants expressing each of the three specific pREs, i.e., pTaqI, pHinP1I, and pMseI, were generated; they showed the leaf variegation phenotypes associated with impaired chloroplast development. We confirmed that these pREs caused double-stranded breaks (DSB) at their recognition sites in ptDNAs. Genome-wide analysis of ptDNAs revealed that the transgenic lines exhibited a large number of rearrangements such as inversions and deletions/duplications, which were dominantly repaired by microhomology-mediated recombination and microhomology-mediated end-joining, and less by non-homologous end-joining. Notably, pHinP1I, which recognized a small number of sites in ptDNA, induced drastic structural changes, including regional copy number variations throughout ptDNAs. In contrast, the transient expression of either pTaqI or pMseI, whose recognition site numbers were relatively larger, resulted in small-scale changes at the whole genome level. These results indicated that DSB frequencies and their distribution are major determinants in shaping ptDNAs.
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Affiliation(s)
- Hiroki Sugimoto
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Minoru Hirano
- Bio System Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Hidenori Tanaka
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Tomoko Tanaka
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Ritsuko Kitagawa-Yogo
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Nobuhiko Muramoto
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Norihiro Mitsukawa
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
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Greiner S, Golczyk H, Malinova I, Pellizzer T, Bock R, Börner T, Herrmann RG. Chloroplast nucleoids are highly dynamic in ploidy, number, and structure during angiosperm leaf development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:730-746. [PMID: 31856320 DOI: 10.1111/tpj.14658] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/20/2019] [Accepted: 12/10/2019] [Indexed: 05/19/2023]
Abstract
Chloroplast nucleoids are large, compact nucleoprotein structures containing multiple copies of the plastid genome. Studies on structural and quantitative changes of plastid DNA (ptDNA) during leaf development are scarce and have produced controversial data. We have systematically investigated nucleoid dynamics and ptDNA quantities in the mesophyll of Arabidopsis, tobacco, sugar beet, and maize from the early post-meristematic stage until necrosis. DNA of individual nucleoids was quantified by DAPI-based supersensitive epifluorescence microscopy. Nucleoids occurred in scattered, stacked, or ring-shaped arrangements and in recurring patterns during leaf development that was remarkably similar between the species studied. Nucleoids per organelle varied from a few in meristematic plastids to >30 in mature chloroplasts (corresponding to about 20-750 nucleoids per cell). Nucleoid ploidies ranged from haploid to >20-fold even within individual organelles, with average values between 2.6-fold and 6.7-fold and little changes during leaf development. DNA quantities per organelle increased gradually from about a dozen plastome copies in tiny plastids of apex cells to 70-130 copies in chloroplasts of about 7 μm diameter in mature mesophyll tissue, and from about 80 plastome copies in meristematic cells to 2600-3300 copies in mature diploid mesophyll cells without conspicuous decline during leaf development. Pulsed-field electrophoresis, restriction of high-molecular-weight DNA from chloroplasts and gerontoplasts, and CsCl equilibrium centrifugation of single-stranded and double-stranded ptDNA revealed no noticeable fragmentation of the organelle DNA during leaf development, implying that plastid genomes in mesophyll tissues are remarkably stable until senescence.
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Affiliation(s)
- Stephan Greiner
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476, Potsdam-Golm, Germany
| | - Hieronim Golczyk
- Department of Molecular Biology, Institute of Biotechnology, John Paul II Catholic University of Lublin, Konstantynów 1i, 20-708, Lublin, Poland
| | - Irina Malinova
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476, Potsdam-Golm, Germany
| | - Tommaso Pellizzer
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476, Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476, Potsdam-Golm, Germany
| | - Thomas Börner
- Institut für Biologie/Molekulare Genetik, Humboldt-Universität zu Berlin, Rhoda Erdmann Haus, Philippstr. 13, D-10115, Berlin, Germany
| | - Reinhold G Herrmann
- Department für Biologie I, Ludwig-Maximilians-Universität München, Bereich Botanik, Menzinger Str. 67, D-80638, Munich, Germany
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The Tempo and Mode of Angiosperm Mitochondrial Genome Divergence Inferred from Intraspecific Variation in Arabidopsis thaliana. G3-GENES GENOMES GENETICS 2020; 10:1077-1086. [PMID: 31964685 PMCID: PMC7056966 DOI: 10.1534/g3.119.401023] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The mechanisms of sequence divergence in angiosperm mitochondrial genomes have long been enigmatic. In particular, it is difficult to reconcile the rapid divergence of intergenic regions that can make non-coding sequences almost unrecognizable even among close relatives with the unusually high levels of sequence conservation found in genic regions. It has been hypothesized that different mutation and repair mechanisms act on genic and intergenic sequences or alternatively that mutational input is relatively constant but that selection has strikingly different effects on these respective regions. To test these alternative possibilities, we analyzed mtDNA divergence within Arabidopsis thaliana, including variants from the 1001 Genomes Project and changes accrued in published mutation accumulation (MA) lines. We found that base-substitution frequencies are relatively similar for intergenic regions and synonymous sites in coding regions, whereas indel and nonsynonymous substitutions rates are greatly depressed in coding regions, supporting a conventional model in which mutation/repair mechanisms are consistent throughout the genome but differentially filtered by selection. Most types of sequence and structural changes were undetectable in 10-generation MA lines, but we found significant shifts in relative copy number across mtDNA regions for lines grown under stressed vs. benign conditions. We confirmed quantitative variation in copy number across the A. thaliana mitogenome using both whole-genome sequencing and droplet digital PCR, further undermining the classic but oversimplified model of a circular angiosperm mtDNA structure. Our results suggest that copy number variation is one of the most fluid features of angiosperm mitochondrial genomes.
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Wynn E, Purfeerst E, Christensen A. Mitochondrial DNA Repair in an Arabidopsis thaliana Uracil N-Glycosylase Mutant. PLANTS (BASEL, SWITZERLAND) 2020; 9:E261. [PMID: 32085412 PMCID: PMC7076443 DOI: 10.3390/plants9020261] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/14/2020] [Accepted: 02/16/2020] [Indexed: 02/07/2023]
Abstract
Substitution rates in plant mitochondrial genes are extremely low, indicating strong selective pressure as well as efficient repair. Plant mitochondria possess base excision repair pathways; however, many repair pathways such as nucleotide excision repair and mismatch repair appear to be absent. In the absence of these pathways, many DNA lesions must be repaired by a different mechanism. To test the hypothesis that double-strand break repair (DSBR) is that mechanism, we maintained independent self-crossing lineages of plants deficient in uracil-N-glycosylase (UNG) for 11 generations to determine the repair outcomes when that pathway is missing. Surprisingly, no single nucleotide polymorphisms (SNPs) were fixed in any line in generation 11. The pattern of heteroplasmic SNPs was also unaltered through 11 generations. When the rate of cytosine deamination was increased by mitochondrial expression of the cytosine deaminase APOBEC3G, there was an increase in heteroplasmic SNPs but only in mature leaves. Clearly, DNA maintenance in reproductive meristem mitochondria is very effective in the absence of UNG while mitochondrial genomes in differentiated tissue are maintained through a different mechanism or not at all. Several genes involved in DSBR are upregulated in the absence of UNG, indicating that double-strand break repair is a general system of repair in plant mitochondria. It is important to note that the developmental stage of tissues is critically important for these types of experiments.
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Affiliation(s)
- Emily Wynn
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (E.W.); (E.P.)
- United States Department of Agriculture, Agricultural Research Service, U.S. Meat Animal Research Center, Clay Center, NE 68933, USA
| | - Emma Purfeerst
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (E.W.); (E.P.)
- Athletics Department, Bethany Lutheran College, Mankato, MN 56001, USA
| | - Alan Christensen
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; (E.W.); (E.P.)
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Tripathi D, Nam A, Oldenburg DJ, Bendich AJ. Reactive Oxygen Species, Antioxidant Agents, and DNA Damage in Developing Maize Mitochondria and Plastids. FRONTIERS IN PLANT SCIENCE 2020; 11:596. [PMID: 32508860 PMCID: PMC7248337 DOI: 10.3389/fpls.2020.00596] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 04/20/2020] [Indexed: 05/14/2023]
Abstract
Maize shoot development progresses from non-pigmented meristematic cells at the base of the leaf to expanded and non-dividing green cells of the leaf blade. This transition is accompanied by the conversion of promitochondria and proplastids to their mature forms and massive fragmentation of both mitochondrial DNA (mtDNA) and plastid DNA (ptDNA), collectively termed organellar DNA (orgDNA). We measured developmental changes in reactive oxygen species (ROS), which at high concentrations can lead to oxidative stress and DNA damage, as well as antioxidant agents and oxidative damage in orgDNA. Our plants were grown under normal, non-stressful conditions. Nonetheless, we found more oxidative damage in orgDNA from leaf than stalk tissues and higher levels of hydrogen peroxide, superoxide, and superoxide dismutase in leaf than stalk tissues and in light-grown compared to dark-grown leaves. In both mitochondria and plastids, activities of the antioxidant enzyme peroxidase were higher in stalk than in leaves and in dark-grown than light-grown leaves. In protoplasts, the amount of the small-molecule antioxidants, glutathione and ascorbic acid, and catalase activity were also higher in the stalk than in leaf tissue. The data suggest that the degree of oxidative stress in the organelles is lower in stalk than leaf and lower in dark than light growth conditions. We speculate that the damaged/fragmented orgDNA in leaves (but not the basal meristem) results from ROS signaling to the nucleus to stop delivering DNA repair proteins to mature organelles producing large amounts of ROS.
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26
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Johnston IG. Tension and Resolution: Dynamic, Evolving Populations of Organelle Genomes within Plant Cells. MOLECULAR PLANT 2019; 12:764-783. [PMID: 30445187 DOI: 10.1016/j.molp.2018.11.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/25/2018] [Accepted: 11/07/2018] [Indexed: 06/09/2023]
Abstract
Mitochondria and plastids form dynamic, evolving populations physically embedded in the fluctuating environment of the plant cell. Their evolutionary heritage has shaped how the cell controls the genetic structure and the physical behavior of its organelle populations. While the specific genes involved in these processes are gradually being revealed, the governing principles underlying this controlled behavior remain poorly understood. As the genetic and physical dynamics of these organelles are central to bioenergetic performance and plant physiology, this challenges both fundamental biology and strategies to engineer better-performing plants. This article reviews current knowledge of the physical and genetic behavior of mitochondria and chloroplasts in plant cells. An overarching hypothesis is proposed whereby organelles face a tension between genetic robustness and individual control and responsiveness, and different species resolve this tension in different ways. As plants are immobile and thus subject to fluctuating environments, their organelles are proposed to favor individual responsiveness, sacrificing genetic robustness. Several notable features of plant organelles, including large genomes, mtDNA recombination, fragmented organelles, and plastid/mitochondrial differences may potentially be explained by this hypothesis. Finally, the ways that quantitative and systems biology can help shed light on the plethora of open questions in this field are highlighted.
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Affiliation(s)
- Iain G Johnston
- School of Biosciences, University of Birmingham, Birmingham, UK; Birmingham Institute for Forest Research, University of Birmingham, Birmingham, UK.
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27
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Baruch-Torres N, Brieba LG. Plant organellar DNA polymerases are replicative and translesion DNA synthesis polymerases. Nucleic Acids Res 2017; 45:10751-10763. [PMID: 28977655 PMCID: PMC5737093 DOI: 10.1093/nar/gkx744] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/14/2017] [Indexed: 02/01/2023] Open
Abstract
Genomes acquire lesions that can block the replication fork and some lesions must be bypassed to allow survival. The nuclear genome of flowering plants encodes two family-A DNA polymerases (DNAPs), the result of a duplication event, that are the sole DNAPs in plant organelles. These DNAPs, dubbed Plant Organellar Polymerases (POPs), resemble the Klenow fragment of bacterial DNAP I and are not related to metazoan and fungal mitochondrial DNAPs. Herein we report that replicative POPs from the plant model Arabidopsis thaliana (AtPolI) efficiently bypass one the most insidious DNA lesions, an apurinic/apyrimidinic (AP) site. AtPolIs accomplish lesion bypass with high catalytic efficiency during nucleotide insertion and extension. Lesion bypass depends on two unique polymerization domain insertions evolutionarily unrelated to the insertions responsible for lesion bypass by DNAP θ, an analogous lesion bypass polymerase. AtPolIs exhibit an insertion fidelity that ranks between the fidelity of replicative and lesion bypass DNAPs, moderate 3′-5′ exonuclease activity and strong strand-displacement. AtPolIs are the first known example of a family-A DNAP evolved to function in both DNA replication and lesion bypass. The lesion bypass capabilities of POPs may be required to prevent replication fork collapse in plant organelles.
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Affiliation(s)
- Noe Baruch-Torres
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, 36821 Irapuato Guanajuato, México
| | - Luis G Brieba
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, 36821 Irapuato Guanajuato, México
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Yang Z, Hou Q, Cheng L, Xu W, Hong Y, Li S, Sun Q. RNase H1 Cooperates with DNA Gyrases to Restrict R-Loops and Maintain Genome Integrity in Arabidopsis Chloroplasts. THE PLANT CELL 2017; 29:2478-2497. [PMID: 28939594 PMCID: PMC5774575 DOI: 10.1105/tpc.17.00305] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 09/05/2017] [Accepted: 09/20/2017] [Indexed: 05/19/2023]
Abstract
Maintaining organellar genome integrity is essential for eukaryotic cells, and many factors can threaten genome integrity. R-loops are DNA:RNA duplexes produced during transcription, with the nontemplated DNA forming a single-stranded region. R-loops function in the regulation of transcription, DNA replication, and DNA repair, but can also be susceptible to lesions that form double-stranded breaks and thus induce genome instability. From investigating the function of a plant chloroplast-localized R-loop removing enzyme AtRNH1C, we have found that it is responsible for plastid R-loop homeostasis, chloroplast genome instability, and development. Interactome analysis revealed that AtRNH1C associates with multiple chloroplast-localized DNA and RNA metabolism-related proteins, including the core DNA gyrases complex. The interaction between AtRNH1C and AtGyrases was critical for R-loop homeostasis in chloroplast and important to release the transcription-replication conflicts in the highly transcribed and replication originated cp-rDNA regions and thus to reduce the DNA damage. Our results reveal the plastid R-loop accumulation leads to chloroplast DNA instability and provide insight into the maintenance of genome integrity in chloroplasts, in which the evolutionarily conserved RNase H1 and DNA gyrase proteins are involved.
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Affiliation(s)
- Zhuo Yang
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Quancan Hou
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lingling Cheng
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wei Xu
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yantao Hong
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shuai Li
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qianwen Sun
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
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Miller ME, Liberatore KL, Kianian SF. Optimization and Comparative Analysis of Plant Organellar DNA Enrichment Methods Suitable for Next-generation Sequencing. J Vis Exp 2017. [PMID: 28784941 DOI: 10.3791/55528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Plant organellar genomes contain large, repetitive elements that may undergo pairing or recombination to form complex structures and/or sub-genomic fragments. Organellar genomes also exist in admixtures within a given cell or tissue type (heteroplasmy), and an abundance of subtypes may change throughout development or when under stress (sub-stoichiometric shifting). Next-generation sequencing (NGS) technologies are required to obtain deeper understanding of organellar genome structure and function. Traditional sequencing studies use several methods to obtain organellar DNA: (1) If a large amount of starting tissue is used, it is homogenized and subjected to differential centrifugation and/or gradient purification. (2) If a smaller amount of tissue is used (i.e., if seeds, material, or space is limited), the same process is performed as in (1), followed by whole-genome amplification to obtain sufficient DNA. (3) Bioinformatics analysis can be used to sequence the total genomic DNA and to parse out organellar reads. All these methods have inherent challenges and tradeoffs. In (1), it may be difficult to obtain such a large amount of starting tissue; in (2), whole-genome amplification could introduce a sequencing bias; and in (3), homology between nuclear and organellar genomes could interfere with assembly and analysis. In plants with large nuclear genomes, it is advantageous to enrich for organellar DNA to reduce sequencing costs and sequence complexity for bioinformatics analyses. Here, we compare a traditional differential centrifugation method with a fourth method, an adapted CpG-methyl pulldown approach, to separate the total genomic DNA into nuclear and organellar fractions. Both methods yield sufficient DNA for NGS, DNA that is highly enriched for organellar sequences, albeit at different ratios in mitochondria and chloroplasts. We present the optimization of these methods for wheat leaf tissue and discuss major advantages and disadvantages of each approach in the context of sample input, protocol ease, and downstream application.
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Affiliation(s)
- Marisa E Miller
- Cereal Disease Laboratory, United States Department of Agriculture-Agricultural Research Service; Department of Horticultural Science, University of Minnesota
| | - Katie L Liberatore
- Cereal Disease Laboratory, United States Department of Agriculture-Agricultural Research Service; Department of Plant Pathology, University of Minnesota
| | - Shahryar F Kianian
- Cereal Disease Laboratory, United States Department of Agriculture-Agricultural Research Service; Department of Plant Pathology, University of Minnesota;
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30
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Cheng N, Lo YS, Ansari MI, Ho KC, Jeng ST, Lin NS, Dai H. Correlation between mtDNA complexity and mtDNA replication mode in developing cotyledon mitochondria during mung bean seed germination. THE NEW PHYTOLOGIST 2017; 213:751-763. [PMID: 27611966 DOI: 10.1111/nph.14158] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 07/18/2016] [Indexed: 05/11/2023]
Abstract
The currently accepted model of recombination-dependent replication (RDR) in plant mitochondrial DNA (mtDNA) does not clearly explain how RDR progresses and how highly complex mtDNA develops. This study aimed to investigate the correlation between RDR and mtDNA complexity during mitochondrial development in mung bean (Vigna radiata) seed, and the initiation and processing of RDR in plant mitochondria. Flow cytometry, pulsed-field gel electrophoresis, electron microscopy, real-time PCR and biochemical studies were used in this study. The highly dynamic changes in mtDNA complexity correspond to mtDNA RDR activity throughout mitochondrial development. With in vitro freeze-thaw treatment or prolonged in vivo cold incubation, the mtDNA rosette core disappeared and the rosette structure converted to a much longer linear DNA structure. D-loops, Holliday junctions and putative RDR forks often appeared near the rosette cores. We hypothesize that the rosette core may consist of condensed mtDNA and a replication starting sequence, and play an initial and central role in RDR. The satellite cores in the rosette structure may represent the re-initiation sites of mtDNA RDR in the same parental molecule, thereby forming highly complex and giant mitochondrial molecules, representing the RDR intermediates, in vivo.
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Affiliation(s)
- Ning Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
- Institute of Plant Biology, National Taiwan University, Taipei, 10617, Taiwan
| | - Yih-Shan Lo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | | | - Kuo-Chieh Ho
- Institute of Plant Biology, National Taiwan University, Taipei, 10617, Taiwan
| | - Shih-Tong Jeng
- Institute of Plant Biology, National Taiwan University, Taipei, 10617, Taiwan
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Hwa Dai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
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31
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R Marcelino V, Cremen MCM, Jackson CJ, Larkum AAW, Verbruggen H. Evolutionary Dynamics of Chloroplast Genomes in Low Light: A Case Study of the Endolithic Green Alga Ostreobium quekettii. Genome Biol Evol 2016; 8:2939-2951. [PMID: 27566760 PMCID: PMC5633697 DOI: 10.1093/gbe/evw206] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Some photosynthetic organisms live in extremely low light environments. Light limitation is associated with selective forces as well as reduced exposure to mutagens, and over evolutionary timescales it can leave a footprint on species’ genomes. Here, we present the chloroplast genomes of four green algae (Bryopsidales, Ulvophyceae), including the endolithic (limestone-boring) alga Ostreobium quekettii, which is a low light specialist. We use phylogenetic models and comparative genomic tools to investigate whether the chloroplast genome of Ostreobium corresponds to our expectations of how low light would affect genome evolution. Ostreobium has the smallest and most gene-dense chloroplast genome among Ulvophyceae reported to date, matching our expectation that light limitation would impose resource constraints reflected in the chloroplast genome architecture. Rates of molecular evolution are significantly slower along the phylogenetic branch leading to Ostreobium, in agreement with the expected effects of low light and energy levels on molecular evolution. We expected the ability of Ostreobium to perform photosynthesis in very low light to be associated with positive selection in genes related to the photosynthetic machinery, but instead, we observed that these genes may be under stronger purifying selection. Besides shedding light on the genome dynamics associated with a low light lifestyle, this study helps to resolve the role of environmental factors in shaping the diversity of genome architectures observed in nature.
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Affiliation(s)
| | | | | | - Anthony A W Larkum
- Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, NSW 2007, Australia
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32
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Havird JC, Sloan DB. The Roles of Mutation, Selection, and Expression in Determining Relative Rates of Evolution in Mitochondrial versus Nuclear Genomes. Mol Biol Evol 2016; 33:3042-3053. [PMID: 27563053 DOI: 10.1093/molbev/msw185] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Eukaryotes rely on proteins encoded by the nuclear and mitochondrial (mt) genomes, which interact within multisubunit complexes such as oxidative-phosphorylation enzymes. Although selection is thought to be less efficient on the asexual mt genome, in bilaterian animals the ratio of nonsynonymous to synonymous substitutions (ω) is lower in mt- compared with nuclear-encoded OXPHOS subunits, suggesting stronger effects of purifying selection in the mt genome. Because high levels of gene expression constrain protein sequence evolution, one proposed resolution to this paradox is that mt genes are expressed more highly than nuclear genes. To test this hypothesis, we investigated expression and sequence evolution of mt and nuclear genes from 84 diverse eukaryotes that vary in mt gene content and mutation rate. We found that the relationship between mt and nuclear ω values varied dramatically across eukaryotes. In contrast, transcript abundance is consistently higher for mt genes than nuclear genes, regardless of which genes happen to be in the mt genome. Consequently, expression levels cannot be responsible for the differences in ω Rather, 84% of the variance in the ratio of ω values between mt and nuclear genes could be explained by differences in mutation rate between the two genomes. We relate these findings to the hypothesis that high rates of mt mutation select for compensatory changes in the nuclear genome. We also propose an explanation for why mt transcripts consistently outnumber their nuclear counterparts, with implications for mitonuclear protein imbalance and aging.
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Affiliation(s)
- Justin C Havird
- Department of Biology, Colorado State University, Fort Collins, CO
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO
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Gonzalez-Hunt CP, Rooney JP, Ryde IT, Anbalagan C, Joglekar R, Meyer JN. PCR-Based Analysis of Mitochondrial DNA Copy Number, Mitochondrial DNA Damage, and Nuclear DNA Damage. ACTA ACUST UNITED AC 2016; 67:20.11.1-20.11.25. [PMID: 26828332 DOI: 10.1002/0471140856.tx2011s67] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Because of the role that DNA damage and depletion play in human disease, it is important to develop and improve tools to assess these endpoints. This unit describes PCR-based methods to measure nuclear and mitochondrial DNA damage and copy number. Long amplicon quantitative polymerase chain reaction (LA-QPCR) is used to detect DNA damage by measuring the number of polymerase-inhibiting lesions present based on the amount of PCR amplification; real-time PCR (RT-PCR) is used to calculate genome content. In this unit, we provide step-by-step instructions to perform these assays in Homo sapiens, Mus musculus, Rattus norvegicus, Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, Oryzias latipes, Fundulus grandis, and Fundulus heteroclitus, and discuss the advantages and disadvantages of these assays.
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Affiliation(s)
| | - John P Rooney
- Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Ian T Ryde
- Nicholas School of the Environment, Duke University, Durham, North Carolina
| | | | - Rashmi Joglekar
- Nicholas School of the Environment, Duke University, Durham, North Carolina
| | - Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, North Carolina
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Odahara M, Inouye T, Nishimura Y, Sekine Y. RECA plays a dual role in the maintenance of chloroplast genome stability in Physcomitrella patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 84:516-526. [PMID: 26340426 DOI: 10.1111/tpj.13017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 08/27/2015] [Accepted: 08/28/2015] [Indexed: 06/05/2023]
Abstract
Chloroplast DNA (cpDNA) encodes essential genes for chloroplast functions, including photosynthesis. Homologous recombination occurs frequently in cpDNA; however, its significance and underlying mechanism remain poorly understood. In this study, we analyzed the role of a nuclear-encoded chloroplast-localized homolog of RecA recombinase, which is a key factor in homologous recombination in bacteria, in the moss Physcomitrella patens. Complete knockout (KO) of the P. patens chloroplast RecA homolog RECA2 caused a modest growth defect and conferred sensitivity to methyl methanesulfonate and UV. The KO mutant exhibited low recovery of cpDNA from methyl methanesulfonate damage, suggesting that RECA2 knockout impairs repair of damaged cpDNA. The RECA2 KO mutant also exhibited reduced cpDNA copy number and an elevated level of cpDNA molecule resulting from aberrant recombination between short dispersed repeats (13-63 bp), indicating that the RECA2 KO chloroplast genome was destabilized. Taken together, these data suggest a dual role for RECA2 in the maintenance of chloroplast genome stability: RECA2 suppresses aberrant recombination between short dispersed repeats and promotes repair of damaged DNA.
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Affiliation(s)
- Masaki Odahara
- Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kita-Shirakawa, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Takayuki Inouye
- Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Yoshiki Nishimura
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kita-Shirakawa, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yasuhiko Sekine
- Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
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35
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Oldenburg DJ, Bendich AJ. DNA maintenance in plastids and mitochondria of plants. FRONTIERS IN PLANT SCIENCE 2015; 6:883. [PMID: 26579143 PMCID: PMC4624840 DOI: 10.3389/fpls.2015.00883] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/05/2015] [Indexed: 05/02/2023]
Abstract
The DNA molecules in plastids and mitochondria of plants have been studied for over 40 years. Here, we review the data on the circular or linear form, replication, repair, and persistence of the organellar DNA (orgDNA) in plants. The bacterial origin of orgDNA appears to have profoundly influenced ideas about the properties of chromosomal DNA molecules in these organelles to the point of dismissing data inconsistent with ideas from the 1970s. When found at all, circular genome-sized molecules comprise a few percent of orgDNA. In cells active in orgDNA replication, most orgDNA is found as linear and branched-linear forms larger than the size of the genome, likely a consequence of a virus-like DNA replication mechanism. In contrast to the stable chromosomal DNA molecules in bacteria and the plant nucleus, the molecular integrity of orgDNA declines during leaf development at a rate that varies among plant species. This decline is attributed to degradation of damaged-but-not-repaired molecules, with a proposed repair cost-saving benefit most evident in grasses. All orgDNA maintenance activities are proposed to occur on the nucleoid tethered to organellar membranes by developmentally-regulated proteins.
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36
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Scarcelli N, Mariac C, Couvreur TLP, Faye A, Richard D, Sabot F, Berthouly‐Salazar C, Vigouroux Y. Intra‐individual polymorphism in chloroplasts from
NGS
data: where does it come from and how to handle it? Mol Ecol Resour 2015; 16:434-45. [DOI: 10.1111/1755-0998.12462] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/07/2015] [Accepted: 08/21/2015] [Indexed: 01/11/2023]
Affiliation(s)
- N. Scarcelli
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
| | - C. Mariac
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
| | - T. L. P. Couvreur
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
- Département des Sciences Biologiques Laboratoire de Botanique Systématique et d'Ecologie Ecole Normale Supérieure Université de Yaoundé I BP 047 Yaoundé Cameroon
| | - A. Faye
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
| | - D. Richard
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
| | - F. Sabot
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
| | - C. Berthouly‐Salazar
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
- Route des Hydrocarbures Centre de Recherche de Bel‐Air IRD/ISRA BP 1386 – 18524 Dakar Senegal
| | - Y. Vigouroux
- UMR DIADE IRD Montpellier 911 avenue Agropolis 34394 Montpellier Cedex 5 France
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37
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Raven JA. Implications of mutation of organelle genomes for organelle function and evolution. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:5639-50. [PMID: 26077836 DOI: 10.1093/jxb/erv298] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Organelle genomes undergo more variation, including that resulting from damage, than eukaryotic nuclear genomes, or bacterial genomes, under the same conditions. Recent advances in characterizing the changes to genomes of chloroplasts and mitochondria of Zea mays should, when applied more widely, help our understanding of how damage to organelle genomes relates to how organelle function is maintained through the life of individuals and in succeeding generations. Understanding of the degree of variation in the changes to organelle DNA and its repair among photosynthetic organisms might help to explain the variations in the rate of nucleotide substitution among organelle genomes. Further studies of organelle DNA variation, including that due to damage and its repair might also help us to understand why the extent of DNA turnover in the organelles is so much greater than that in their bacterial (cyanobacteria for chloroplasts, proteobacteria for mitochondria) relatives with similar rates of production of DNA-damaging reactive oxygen species. Finally, from the available data, even the longest-lived organelle-encoded proteins, and the RNAs needed for their synthesis, are unlikely to maintain organelle function for much more than a week after the complete loss of organelle DNA.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK †School of Plant Biology, University of Western Australia, M048, 35 Stirling Highway, Crawley, WA 6009, Australia
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Wu CS, Chaw SM. Evolutionary Stasis in Cycad Plastomes and the First Case of Plastome GC-Biased Gene Conversion. Genome Biol Evol 2015; 7:2000-9. [PMID: 26116919 PMCID: PMC4524490 DOI: 10.1093/gbe/evv125] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2015] [Indexed: 01/09/2023] Open
Abstract
In angiosperms, gene conversion has been known to reduce the mutational load of plastid genomes (the plastomes). Particularly, more frequent gene conversions in inverted repeat (IR) than in single copy (SC) regions result in contrasting substitution rates between these two regions. However, little has been known about the effect of gene conversion in the evolution of gymnosperm plastomes. Cycads (Cycadophyta) are the second largest gymnosperm group. Evolutionary study of their plastomes is limited to the basal cycad genus, Cycas. In this study, we addressed three questions. 1) Do the plastomes of other cycad genera evolve slowly as previously observed in the plastome of Cycas taitungensis? 2) Do substitution rates differ between their SC and IR regions? And 3) Does gene conversion occur in the cycad plastomes? If yes, is it AT-biased or GC-biased? Plastomes of eight species from other eight genera of cycads were sequenced. These plastomes are highly conserved in genome organization. Excluding ginkgo, cycad plastomes have significantly lower synonymous and nonsynonymous substitution rates than other gymnosperms, reflecting their evolutionary stasis in nucleotide mutations. In the IRs of cycad plastomes, the reduced substitution rates and GC-biased mutations are associated with a GC-biased gene conversion (gBGC) mechanism. Further investigations suggest that in cycads, gBGC is able to rectify plastome-wide mutations. Therefore, this study is the first to uncover the plastomic gBGC in seed plants. We also propose a gBGC model to interpret the dissimilar evolutionary patterns as well as the compositionally biased mutations in the SC and IR regions of cycad plastomes.
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Affiliation(s)
- Chung-Shien Wu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Shu-Miaw Chaw
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
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Kumar RA, Oldenburg DJ, Bendich AJ. Molecular integrity of chloroplast DNA and mitochondrial DNA in mesophyll and bundle sheath cells of maize. PLANTA 2015; 241:1221-30. [PMID: 25638645 DOI: 10.1007/s00425-015-2253-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/22/2015] [Indexed: 05/10/2023]
Abstract
When compared to maize mesophyll cells, the plastid and mitochondrial DNAs in bundle sheath cells are less fragmented, less damaged, and contain fewer DNA polymerase-blocking impediments. Plants that conduct C4 photosynthesis differ from those that employ C3 photosynthesis with respect to leaf anatomy, biochemical pathways, and the proteins and RNA transcripts present in the leaf mesophyll (M) and bundle sheath (BS) cells. Here, we investigate the organellar DNA (orgDNA) from plastids and mitochondria in these two cell types. We use standard qPCR, long PCR, and DNA damage analysis to quantify the amount and quality of orgDNA in isolated M and BS cells of maize. When compared to M cells, BS cells have less orgDNA damage and a higher percentage of unimpeded orgDNA. In addition, the orgDNA is more fragmented in M than BS cells, although orgDNA in BS is subject to more in vitro repair. We suggest that the differences in molecular integrity of orgDNA in these two cells are due to higher levels of reactive oxygen species in M than BS cells.
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Affiliation(s)
- Rachana A Kumar
- Department of Biology, University of Washington, Seattle, WA, 98195-5325, USA
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Raven JA, Griffiths H. Photosynthesis in reproductive structures: costs and benefits. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1699-705. [PMID: 25871648 PMCID: PMC4669558 DOI: 10.1093/jxb/erv009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 05/18/2023]
Abstract
The role of photosynthesis by reproductive structures during grain-filling has important implications for cereal breeding, but the methods for assessing the contribution by reproductive structures to grain-filling are invasive and prone to compensatory changes elsewhere in the plant. A technique analysing the natural abundance of stable carbon isotopes in soluble carbohydrates has significant promise. However, it depends crucially on there being no more than two sources of organic carbon (leaf and ear/awn), with significantly different (13)C:(12)C ratios and no secondary fractionation during grain-filling. The role of additional peduncle carbohydrate reserves represents a potential means for N remobilization, as well as for hydraulic continuity during grain-filling. The natural abundance of the stable isotopes of carbon and oxygen are also useful for exploring the influence of reproduction on whole plant carbon and water relations and have been used to examine the resource costs of reproduction in females and males of dioecious plants. Photosynthesis in reproductive structures is widespread among oxygenic photosynthetic organisms, including many clades of algae and embryophytes of different levels of complexity. The possible evolutionary benefits of photosynthesis in reproductive structures include decreasing the carbon cost of reproduction and 'use' of transpiratory loss of water to deliver phloem-immobile calcium Ca(2+) and silicon [Si(OH)4] via the xylem. The possible costs of photosynthesis in reproductive structures are increasing damage to DNA from photosynthetically active, and hence UV-B, radiation and the production of reactive oxygen species.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK , and School of Plant Biology, University of Western Australia, M048, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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Ma J, Li XQ. Organellar genome copy number variation and integrity during moderate maturation of roots and leaves of maize seedlings. Curr Genet 2015; 61:591-600. [PMID: 25782449 DOI: 10.1007/s00294-015-0482-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 03/01/2015] [Accepted: 03/03/2015] [Indexed: 01/30/2023]
Abstract
Little information is available about organellar genome copy numbers and integrity in plant roots, although it was reported recently that the plastid and mitochondrial genomes were damaged under light, resulting in non-functional fragments in green seedling leaves in a maize line. In the present study, we investigated organellar genome copy numbers and integrity, after assessing the cellular ploidy, in seedling leaves and roots of two elite maize (Zea mays) cultivars using both long-fragment polymerase chain reaction (long-PCR) and real-time quantitative polymerase chain reaction (qPCR, a type of short-PCR). Since maize leaf and root cells are mainly diploid according to chromosome number counting and the literature, the DNA amount ratio between the organellar genomes and the nuclear genome could be used to estimate average organellar genome copy numbers per cell. In the present study, both long-PCR and qPCR analyses found that green leaves had dramatically more plastid DNA and less mitochondrial DNA than roots had in both cultivars. The similarity in results from long-PCR and qPCR suggests that green leaves and roots during moderate maturation have largely intact plastid and mitochondrial genomes. The high resolution of qPCR led to the detection of an increase in copies in the plastid genome and a decrease in copies in the analyzed mitochondrial sub-genomes during the moderate maturation of seedling leaves and roots. These results suggest that green seedling leaves and roots of these two maize cultivars during moderate maturation had essentially intact organellar genomes, an increased copy number of the plastid genome, and decreased copy numbers of certain mitochondrial sub-genomes.
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Affiliation(s)
- Jin Ma
- Potato Research Centre, Agriculture and Agri-Food Canada, 850 Lincoln Road, P.O. Box 20280, Fredericton, NB, E3B 4Z7, Canada
| | - Xiu-Qing Li
- Potato Research Centre, Agriculture and Agri-Food Canada, 850 Lincoln Road, P.O. Box 20280, Fredericton, NB, E3B 4Z7, Canada.
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Chloroplast RNA polymerases: Role in chloroplast biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:761-9. [PMID: 25680513 DOI: 10.1016/j.bbabio.2015.02.004] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 01/26/2015] [Accepted: 02/02/2015] [Indexed: 12/18/2022]
Abstract
Plastid genes are transcribed by two types of RNA polymerase in angiosperms: the bacterial type plastid-encoded RNA polymerase (PEP) and one (RPOTp in monocots) or two (RPOTp and RPOTmp in dicots) nuclear-encoded RNA polymerase(s) (NEP). PEP is a bacterial-type multisubunit enzyme composed of core subunits (coded for by the plastid rpoA, rpoB, rpoC1 and rpoC2 genes) and additional protein factors (sigma factors and polymerase associated protein, PAPs) encoded in the nuclear genome. Sigma factors are required by PEP for promoter recognition. Six different sigma factors are used by PEP in Arabidopsis plastids. NEP activity is represented by phage-type RNA polymerases. Only one NEP subunit has been identified, which bears the catalytic activity. NEP and PEP use different promoters. Many plastid genes have both PEP and NEP promoters. PEP dominates in the transcription of photosynthesis genes. Intriguingly, rpoB belongs to the few genes transcribed exclusively by NEP. Both NEP and PEP are active in non-green plastids and in chloroplasts at all stages of development. The transcriptional activity of NEP and PEP is affected by endogenous and exogenous factors. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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