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Ochiai KK, Hanawa D, Ogawa HA, Tanaka H, Uesaka K, Edzuka T, Shirae-Kurabayashi M, Toyoda A, Itoh T, Goshima G. Genome sequence and cell biological toolbox of the highly regenerative, coenocytic green feather alga Bryopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 119:1091-1111. [PMID: 38642374 DOI: 10.1111/tpj.16764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 02/10/2024] [Accepted: 03/27/2024] [Indexed: 04/22/2024]
Abstract
Green feather algae (Bryopsidales) undergo a unique life cycle in which a single cell repeatedly executes nuclear division without cytokinesis, resulting in the development of a thallus (>100 mm) with characteristic morphology called coenocyte. Bryopsis is a representative coenocytic alga that has exceptionally high regeneration ability: extruded cytoplasm aggregates rapidly in seawater, leading to the formation of protoplasts. However, the genetic basis of the unique cell biology of Bryopsis remains poorly understood. Here, we present a high-quality assembly and annotation of the nuclear genome of Bryopsis sp. (90.7 Mbp, 27 contigs, N50 = 6.7 Mbp, 14 034 protein-coding genes). Comparative genomic analyses indicate that the genes encoding BPL-1/Bryohealin, the aggregation-promoting lectin, are heavily duplicated in Bryopsis, whereas homologous genes are absent in other ulvophyceans, suggesting the basis of regeneration capability of Bryopsis. Bryopsis sp. possesses >30 kinesins but only a single myosin, which differs from other green algae that have multiple types of myosin genes. Consistent with this biased motor toolkit, we observed that the bidirectional motility of chloroplasts in the cytoplasm was dependent on microtubules but not actin in Bryopsis sp. Most genes required for cytokinesis in plants are present in Bryopsis, including those in the SNARE or kinesin superfamily. Nevertheless, a kinesin crucial for cytokinesis initiation in plants (NACK/Kinesin-7II) is hardly expressed in the coenocytic part of the thallus, possibly underlying the lack of cytokinesis in this portion. The present genome sequence lays the foundation for experimental biology in coenocytic macroalgae.
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Affiliation(s)
- Kanta K Ochiai
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Toba, 517-0004, Japan
| | - Daiki Hanawa
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8550, Japan
| | - Harumi A Ogawa
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Toba, 517-0004, Japan
| | - Hiroyuki Tanaka
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8550, Japan
| | - Kazuma Uesaka
- Centre for Gene Research, Nagoya University, Nagoya, 464-8602, Japan
| | - Tomoya Edzuka
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Toba, 517-0004, Japan
| | - Maki Shirae-Kurabayashi
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Toba, 517-0004, Japan
| | - Atsushi Toyoda
- Comparative Genomics Laboratory, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
- Advanced Genomics Center, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan
| | - Takehiko Itoh
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8550, Japan
| | - Gohta Goshima
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Toba, 517-0004, Japan
- Department of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan
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Every refuge has its price: Ostreobium as a model for understanding how algae can live in rock and stay in business. Semin Cell Dev Biol 2023; 134:27-36. [PMID: 35341677 DOI: 10.1016/j.semcdb.2022.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 02/20/2022] [Accepted: 03/08/2022] [Indexed: 11/23/2022]
Abstract
Ostreobium is a siphonous green alga in the Bryopsidales (Chlorophyta) that burrows into calcium carbonate (CaCO3) substrates. In this habitat, it lives under environmental conditions unusual for an alga (i.e., low light and low oxygen) and it is a major agent of carbonate reef bioerosion. In coral skeletons, Ostreobium can form conspicuous green bands recognizable by the naked eye and it is thought to contribute to the coral's nutritional needs. With coral reefs in global decline, there is a renewed focus on understanding Ostreobium biology and its roles in the coral holobiont. This review summarizes knowledge on Ostreobium's morphological structure, biodiversity and evolution, photosynthesis, mechanism of bioerosion and its role as a member of the coral holobiont. We discuss the resources available to study Ostreobium biology, lay out some of the uncharted territories in Ostreobium biology and offer perspectives for future research.
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Robison T, Nelson JM, Hauser DA, Lewis LA, Li FW. Dynamic plastid and mitochondrial genomes in Chaetopeltidales (Chlorophyceae) and characterization of a new chlorophyte taxon. AMERICAN JOURNAL OF BOTANY 2022; 109:939-951. [PMID: 35678538 DOI: 10.1002/ajb2.16015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 03/31/2022] [Accepted: 04/01/2022] [Indexed: 06/15/2023]
Abstract
PREMISE Chaetopeltidales is a poorly characterized order in the Chlorophyceae, with only two plastid and no mitochondrial genomes published. Here we describe a new taxon in Chaetopeltidales, Gormaniella terricola gen. et sp. nov. and characterize both of its organellar genomes. METHODS Gormaniella terricola was inadvertently isolated from a surface-sterilized hornwort thallus. Light microscopy was used to characterize its vegetative morphology. Organellar genomes were assembled, annotated, and analyzed using a variety of software packages. RESULTS The mitochondrial genome (66,927 bp) represents the first complete mitochondrial genome published for Chaetopeltidales. The chloroplast genome, measuring 428,981 bp, is one of the largest plastid genomes published to date and shares this large size and an incredible number of short, dispersed repeats with the other sequenced chloroplast genomes in Chaetopeltidales. Despite these shared features, the chloroplast genomes of Chaetopeltidales appear to be highly rearranged when compared to one another, with numerous inversions, translocations, and duplications, suggesting a particularly dynamic chloroplast genome. Both the chloroplast and mitochondrial genomes of G. terricola contain a number of mobile group I and group II introns, which appear to have invaded separately. Three of the introns within the mitochondrial genome encode homing endonucleases that are phylogenetically nested within those found in fungi, rather than algae, suggesting a possible case of horizontal gene transfer. CONCLUSIONS These results help to shed light on a poorly understood group of algae and their unusual organellar genomes, raising additional questions about the unique patterns of genome evolution within Chaetopeltidales.
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Affiliation(s)
- Tanner Robison
- Plant Biology Section, Cornell University, Ithaca, NY, USA
- Boyce Thompson Institute, Ithaca, NY, USA
| | | | | | - Louise A Lewis
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Fay-Wei Li
- Plant Biology Section, Cornell University, Ithaca, NY, USA
- Boyce Thompson Institute, Ithaca, NY, USA
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Liu F, Wang H, Song W. Tandem integration of circular plasmid contributes significantly to the expanded mitochondrial genomes of the green-tide forming alga Ulva meridionalis (Ulvophyceae, Chlorophyta). FRONTIERS IN PLANT SCIENCE 2022; 13:937398. [PMID: 35991460 PMCID: PMC9389341 DOI: 10.3389/fpls.2022.937398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/05/2022] [Indexed: 05/22/2023]
Abstract
Comparative mitogenomics of Ulva species have revealed remarkable variations in genome size due to the integration of exogenous DNA fragments, the proliferation of group I/II introns, and the change of repeat sequences. The genus Ulva is a species-rich taxonomic group, containing a variety of green-tide forming algae. In this study, five complete mitogenomes of the green-tide forming macroalga, Ulva meridionalis R. Horimoto and S. Shimada, were assembled and compared with the available ulvophyceae mtDNAs. The main circular mitogenomes of U. meridionalis ranged from 82.94 to 111.49 kb in size, and its 111.49-kb mitogenome was the largest Ulva mitogenome sequenced so far. The expansion of U. meridionalis mitogenomes is mainly due to the tandem integration of a 5.36-kb mitochondrial circular plasmid (pUme), as well as the proliferation of introns. An intact DNA-directed RNA polymerase gene (rpo) was present in pUme of U. meridionalis and was then detected in two putative plasmids (pUmu1 and pUmu2) found in Ulva mutabilis. The observed integration of the circular plasmid into U. meridionalis mitogenomes seems to occur via homologous recombination, and is a more recent evolutionary event. Many highly homologous sequences of these three putative plasmids can be detected in the other Ulva mtDNAs sequenced thus far, indicating the integration of different mitochondrial plasmid DNA into the mitogenomes is a common phenomenon in the evolution of Ulva mitogenomes. The random incidence of destruction of plasmid-derived rpos and open reading frames (orfs) suggests that their existence is not the original characteristic of Ulva mitogenomes and there is no selective pressure to maintain their integrity. The frequent integration and rapid divergence of plasmid-derived sequences is one of the most important evolutionary forces to shape the diversity of Ulva mitogenomes.
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Affiliation(s)
- Feng Liu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Marine Ecology and Environmental Science Laboratory, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
- *Correspondence: Feng Liu, ,
| | - Hongshu Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Marine Ecology and Environmental Science Laboratory, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Wenli Song
- Rongcheng Ecological Civilization Construction Coordination Center, Weihai, China
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Kim H, Yang JH, Bustamante DE, Calderon MS, Mansilla A, Maggs CA, Hansen GI, Yoon HS. Organelle Genome Variation in the Red Algal Genus Ahnfeltia (Florideophyceae). Front Genet 2021; 12:724734. [PMID: 34646303 PMCID: PMC8503264 DOI: 10.3389/fgene.2021.724734] [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: 06/14/2021] [Accepted: 09/09/2021] [Indexed: 11/13/2022] Open
Abstract
The agarophyte Ahnfeltia (Ahnfeltiales, Rhodophyta) is a globally widespread genus with 11 accepted species names. Two of the most widespread species in this genus, A. plicata and A. fastigiata, may have diverged genetically due to past geographic changes and subsequent geographic isolation. To investigate this genomic and genetic diversity, we generated new plastid (ptDNAs) and mitochondrial genomes (mtDNAs) of these Ahnfeltia species from four different regions (A. plicata - Chile and UK and A. fastigiata - Korea and Oregon). Two architecture variations were found in the Ahnfeltia genomes: in ptDNA of A. fastigiata Oregon, the hypothetical pseudogene region was translocated, likely due to recombination with palindromic repeats or a gene transfer from a red algal plasmid. In mtDNA of A. fastigiata Korea, the composition of the group II intronic ORFs was distinct from others suggesting different scenarios of gain and loss of group II intronic ORFs. These features resulted in genome size differences between the two species. Overall gene contents of organelle genomes of Ahnfeltia were conserved. Phylogenetic analysis using concatenated genes from ptDNAs and mtDNAs supported the monophyly of the Ahnfeltiophycidae. The most probable individual gene trees showed that the Ahnfeltia populations were genetically diversified. These trees, the cox1 haplotype network, and a dN/dS analysis all supported the theory that these Ahnfeltia populations have diversified genetically in accordance with geographic distribution.
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Affiliation(s)
- Hocheol Kim
- Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
| | - Ji Hyun Yang
- Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
| | - Danilo E Bustamante
- Instituto de Investigación para el Desarrollo Sustentable de Ceja de Selva (INDES-CES), Universidad Nacional Toribio Rodríguez de Mendoza, Chachapoyas, Peru
| | - Martha S Calderon
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, Punta Arenas, Chile
| | - Andres Mansilla
- Laboratorio de Macroalgas Antárticas y Subantárticas, Universidad de Magallanes, Punta Arenas, Chile
| | - Christine A Maggs
- School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Gayle I Hansen
- Marine Algal Biodiversity Research, Newport, OR, United States
| | - Hwan Su Yoon
- Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea
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Mukhopadhyay J, Hausner G. Organellar Introns in Fungi, Algae, and Plants. Cells 2021; 10:cells10082001. [PMID: 34440770 PMCID: PMC8393795 DOI: 10.3390/cells10082001] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/31/2021] [Accepted: 08/05/2021] [Indexed: 12/16/2022] Open
Abstract
Introns are ubiquitous in eukaryotic genomes and have long been considered as ‘junk RNA’ but the huge energy expenditure in their transcription, removal, and degradation indicate that they may have functional significance and can offer evolutionary advantages. In fungi, plants and algae introns make a significant contribution to the size of the organellar genomes. Organellar introns are classified as catalytic self-splicing introns that can be categorized as either Group I or Group II introns. There are some biases, with Group I introns being more frequently encountered in fungal mitochondrial genomes, whereas among plants Group II introns dominate within the mitochondrial and chloroplast genomes. Organellar introns can encode a variety of proteins, such as maturases, homing endonucleases, reverse transcriptases, and, in some cases, ribosomal proteins, along with other novel open reading frames. Although organellar introns are viewed to be ribozymes, they do interact with various intron- or nuclear genome-encoded protein factors that assist in the intron RNA to fold into competent splicing structures, or facilitate the turn-over of intron RNAs to prevent reverse splicing. Organellar introns are also known to be involved in non-canonical splicing, such as backsplicing and trans-splicing which can result in novel splicing products or, in some instances, compensate for the fragmentation of genes by recombination events. In organellar genomes, Group I and II introns may exist in nested intronic arrangements, such as introns within introns, referred to as twintrons, where splicing of the external intron may be dependent on splicing of the internal intron. These nested or complex introns, with two or three-component intron modules, are being explored as platforms for alternative splicing and their possible function as molecular switches for modulating gene expression which could be potentially applied towards heterologous gene expression. This review explores recent findings on organellar Group I and II introns, focusing on splicing and mobility mechanisms aided by associated intron/nuclear encoded proteins and their potential roles in organellar gene expression and cross talk between nuclear and organellar genomes. Potential application for these types of elements in biotechnology are also discussed.
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MESH Headings
- Evolution, Molecular
- Gene Expression Regulation, Fungal
- Gene Expression Regulation, Plant
- Genome, Fungal
- Genome, Plant
- Introns
- Organelles/genetics
- Organelles/metabolism
- RNA Splicing
- RNA Stability
- RNA, Algal/genetics
- RNA, Algal/metabolism
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
- Transcription, Genetic
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Mitochondrial Genomic Landscape: A Portrait of the Mitochondrial Genome 40 Years after the First Complete Sequence. Life (Basel) 2021; 11:life11070663. [PMID: 34357035 PMCID: PMC8303319 DOI: 10.3390/life11070663] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/02/2021] [Accepted: 07/03/2021] [Indexed: 12/11/2022] Open
Abstract
Notwithstanding the initial claims of general conservation, mitochondrial genomes are a largely heterogeneous set of organellar chromosomes which displays a bewildering diversity in terms of structure, architecture, gene content, and functionality. The mitochondrial genome is typically described as a single chromosome, yet many examples of multipartite genomes have been found (for example, among sponges and diplonemeans); the mitochondrial genome is typically depicted as circular, yet many linear genomes are known (for example, among jellyfish, alveolates, and apicomplexans); the chromosome is normally said to be “small”, yet there is a huge variation between the smallest and the largest known genomes (found, for example, in ctenophores and vascular plants, respectively); even the gene content is highly unconserved, ranging from the 13 oxidative phosphorylation-related enzymatic subunits encoded by animal mitochondria to the wider set of mitochondrial genes found in jakobids. In the present paper, we compile and describe a large database of 27,873 mitochondrial genomes currently available in GenBank, encompassing the whole eukaryotic domain. We discuss the major features of mitochondrial molecular diversity, with special reference to nucleotide composition and compositional biases; moreover, the database is made publicly available for future analyses on the MoZoo Lab GitHub page.
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Starko S, Bringloe TT, Soto Gomez M, Darby H, Graham SW, Martone PT. Genomic Rearrangements and Sequence Evolution across Brown Algal Organelles. Genome Biol Evol 2021; 13:evab124. [PMID: 34061182 PMCID: PMC8290108 DOI: 10.1093/gbe/evab124] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2021] [Indexed: 02/06/2023] Open
Abstract
Organellar genomes serve as useful models for genome evolution and contain some of the most widely used phylogenetic markers, but they are poorly characterized in many lineages. Here, we report 20 novel mitochondrial genomes and 16 novel plastid genomes from the brown algae. We focused our efforts on the orders Chordales and Laminariales but also provide the first plastid genomes (plastomes) from Desmarestiales and Sphacelariales, the first mitochondrial genome (mitome) from Ralfsiales and a nearly complete mitome from Sphacelariales. We then compared gene content, sequence evolution rates, shifts in genome structural arrangements, and intron distributions across lineages. We confirm that gene content is largely conserved in both organellar genomes across the brown algal tree of life, with few cases of gene gain or loss. We further show that substitution rates are generally lower in plastid than mitochondrial genes, but plastomes are more variable in gene arrangement, as mitomes tend to be colinear even among distantly related lineages (with exceptions). Patterns of intron distribution across organellar genomes are complex. In particular, the mitomes of several laminarialean species possess group II introns that have T7-like ORFs, found previously only in mitochondrial genomes of Pylaiella spp. (Ectocarpales). The distribution of these mitochondrial introns is inconsistent with vertical transmission and likely reflects invasion by horizontal gene transfer between lineages. In the most extreme case, the mitome of Hedophyllum nigripes is ∼40% larger than the mitomes of close relatives because of these introns. Our results provide substantial insight into organellar evolution across the brown algae.
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Affiliation(s)
- Samuel Starko
- Department of Biology, University of Victoria, Victoria, Canada
- Department of Botany & Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Trevor T Bringloe
- Department of BioSciences, University of Melbourne, Melbourne, Australia
| | - Marybel Soto Gomez
- Department of Botany & Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Hayley Darby
- Department of Botany & Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Sean W Graham
- Department of Botany & Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Patrick T Martone
- Department of Botany & Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
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Plazzi F, Puccio G, Passamonti M. HERMES: An improved method to test mitochondrial genome molecular synapomorphies among clades. Mitochondrion 2021; 58:285-295. [PMID: 33639269 DOI: 10.1016/j.mito.2021.02.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/10/2021] [Accepted: 02/12/2021] [Indexed: 02/06/2023]
Abstract
Mitochondrial chromosomes have diversified among eukaryotes and many different architectures and features are now acknowledged for this genome. Here we present the improved HERMES index, which can measure and quantify the amount of molecular change experienced by mitochondrial genomes. We test the improved approach with ten molecular phylogenetic studies based on complete mitochondrial genomes, representing six bilaterian Phyla. In most cases, HERMES analysis spotted out clades or single species with peculiar molecular synapomorphies, allowing to identify phylogenetic and ecological patterns. The software presented herein handles linear, circular, and multi-chromosome genomes, thus widening the HERMES scope to the complete eukaryotic domain.
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Affiliation(s)
- Federico Plazzi
- Department of Biological, Geological and Environmental Sciences, University of Bologna, via Selmi, 3, 40126 Bologna, Italy.
| | - Guglielmo Puccio
- Department of Biological, Geological and Environmental Sciences, University of Bologna, via Selmi, 3, 40126 Bologna, Italy.
| | - Marco Passamonti
- Department of Biological, Geological and Environmental Sciences, University of Bologna, via Selmi, 3, 40126 Bologna, Italy.
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Iha C, Dougan KE, Varela JA, Avila V, Jackson CJ, Bogaert KA, Chen Y, Judd LM, Wick R, Holt KE, Pasella MM, Ricci F, Repetti SI, Medina M, Marcelino VR, Chan CX, Verbruggen H. Genomic adaptations to an endolithic lifestyle in the coral-associated alga Ostreobium. Curr Biol 2021; 31:1393-1402.e5. [PMID: 33548192 DOI: 10.1016/j.cub.2021.01.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/21/2020] [Accepted: 01/07/2021] [Indexed: 02/06/2023]
Abstract
The green alga Ostreobium is an important coral holobiont member, playing key roles in skeletal decalcification and providing photosynthate to bleached corals that have lost their dinoflagellate endosymbionts. Ostreobium lives in the coral's skeleton, a low-light environment with variable pH and O2 availability. We present the Ostreobium nuclear genome and a metatranscriptomic analysis of healthy and bleached corals to improve our understanding of Ostreobium's adaptations to its extreme environment and its roles as a coral holobiont member. The Ostreobium genome has 10,663 predicted protein-coding genes and shows adaptations for life in low and variable light conditions and other stressors in the endolithic environment. This alga presents a rich repertoire of light-harvesting complex proteins but lacks many genes for photoprotection and photoreceptors. It also has a large arsenal of genes for oxidative stress response. An expansion of extracellular peptidases suggests that Ostreobium may supplement its energy needs by feeding on the organic skeletal matrix, and a diverse set of fermentation pathways allows it to live in the anoxic skeleton at night. Ostreobium depends on other holobiont members for vitamin B12, and our metatranscriptomes identify potential bacterial sources. Metatranscriptomes showed Ostreobium becoming a dominant agent of photosynthesis in bleached corals and provided evidence for variable responses among coral samples and different Ostreobium genotypes. Our work provides a comprehensive understanding of the adaptations of Ostreobium to its extreme environment and an important genomic resource to improve our comprehension of coral holobiont resilience, bleaching, and recovery.
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Affiliation(s)
- Cintia Iha
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia.
| | - Katherine E Dougan
- School of Chemistry and Molecular Biosciences and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Javier A Varela
- School of Microbiology, Centre for Synthetic Biology and Biotechnology, Environmental Research Institute, and APC Microbiome Institute, University College Cork, Cork T12 YN60, Ireland
| | - Viridiana Avila
- Pennsylvania State University, University Park, PA 16802, USA
| | | | - Kenny A Bogaert
- Phycology Research Group, Ghent University, Krijgslaan 281 S8, 9000 Gent, Belgium
| | - Yibi Chen
- School of Chemistry and Molecular Biosciences and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Louise M Judd
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Ryan Wick
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Kathryn E Holt
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Marisa M Pasella
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Francesco Ricci
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Sonja I Repetti
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mónica Medina
- Pennsylvania State University, University Park, PA 16802, USA
| | - Vanessa R Marcelino
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia
| | - Cheong Xin Chan
- School of Chemistry and Molecular Biosciences and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Heroen Verbruggen
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia.
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Fang J, Liu B, Liu G, Verbruggen H, Zhu H. Six Newly Sequenced Chloroplast Genomes From Trentepohliales: The Inflated Genomes, Alternative Genetic Code and Dynamic Evolution. FRONTIERS IN PLANT SCIENCE 2021; 12:780054. [PMID: 34956275 PMCID: PMC8692980 DOI: 10.3389/fpls.2021.780054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/15/2021] [Indexed: 05/17/2023]
Abstract
Cephaleuros is often known as an algal pathogen with 19 taxonomically valid species, some of which are responsible for red rust and algal spot diseases in vascular plants. No chloroplast genomes have yet been reported in this genus, and the limited genetic information is an obstacle to understanding the evolution of this genus. In this study, we sequenced six new Trentepohliales chloroplast genomes, including four Cephaleuros and two Trentepohlia. The chloroplast genomes of Trentepohliales are large compared to most green algae, ranging from 216 to 408 kbp. They encode between 93 and 98 genes and have a GC content of 26-36%. All new chloroplast genomes were circular-mapping and lacked a quadripartite structure, in contrast to the previously sequenced Trentepohlia odorata, which does have an inverted repeat. The duplicated trnD -GTC, petD, and atpA genes in C. karstenii may be remnants of the IR region and shed light on its reduction. Chloroplast genes of Trentepohliales show elevated rates of evolution, strong rearrangement dynamics and several genes display an alternative genetic code with reassignment of the UGA/UAG codon presumably coding for arginine. Our results present the first whole chloroplast genome of the genus Cephaleuros and enrich the chloroplast genome resources of Trentepohliales.
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Affiliation(s)
- Jiao Fang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Benwen Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Guoxiang Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Heroen Verbruggen
- School of BioSciences, University of Melbourne, Melbourne, VIC, Australia
| | - Huan Zhu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- *Correspondence: Huan Zhu,
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Díaz-Tapia P, Ly M, Verbruggen H. Extensive cryptic diversity in the widely distributed Polysiphonia scopulorum (Rhodomelaceae, Rhodophyta): Molecular species delimitation and morphometric analyses. Mol Phylogenet Evol 2020; 152:106909. [PMID: 32702527 DOI: 10.1016/j.ympev.2020.106909] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 06/30/2020] [Accepted: 07/15/2020] [Indexed: 10/23/2022]
Abstract
Our knowledge of seaweed diversity and biogeography still largely relies on information derived from morphological identifications, but the use of molecular tools is revealing that cryptic diversity is common among algae. Polysiphonia scopulorum is a turf-forming red alga widely reported in tropical and temperate coasts worldwide. The only study based on material collected from its Australian type locality and the Iberian Peninsula indicates that it is a species complex, but the extent of cryptic diversity across its geographical range is not known. To investigate the species diversity in P. scopulorum, the geographical distribution of species-level lineages and their morphological characterization, we collected 135 specimens from Australia, South Africa and southern Europe. Two gene datasets (cox1 and rbcL) were used to delimit species using three methods (GMYC, PTP, ABGD), leading to a consensus result that our collections of the P. scopulorum complex comprise 12 species. Five of these species were resolved in a highly supported clade, while the other seven species were related to other taxonomically accepted species or in unresolved parts of the tree. Morphometric and statistical analysis of a set of ten quantitative characters showed that there are no clear morphological correlates of species boundaries, demonstrating true cryptic diversity in the P. scopulorum complex. Distribution patterns of the 12 species were variable, ranging from species only known from a single site to species with a wide distribution spanning three continents. Our study indicates that a significant level of undiscovered cryptic diversity is likely to be found in algal turfs, a type of seaweed community formed by small entangled species.
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Affiliation(s)
- Pilar Díaz-Tapia
- School of BioSciences, University of Melbourne, Victoria 3010, Australia; Coastal Biology Research Group, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of A Coruña, 15071 A Coruña, Spain; Instituto Español de Oceanografía (IEO), Centro Oceanográfico de A Coruña, Aptdo. 130, 15080 A Coruña, Spain.
| | - Monica Ly
- School of BioSciences, University of Melbourne, Victoria 3010, Australia.
| | - Heroen Verbruggen
- School of BioSciences, University of Melbourne, Victoria 3010, Australia.
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Smith DR. Common Repeat Elements in the Mitochondrial and Plastid Genomes of Green Algae. Front Genet 2020; 11:465. [PMID: 32477407 PMCID: PMC7235400 DOI: 10.3389/fgene.2020.00465] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 04/15/2020] [Indexed: 12/31/2022] Open
Abstract
Despite both originating from endosymbiotic bacteria, one does not typically expect mitochondrial DNA (mtDNA) to show strong sequence identity to plastid DNA (ptDNA). Nevertheless, a recent analysis of Haematococcus lacustris revealed exactly that. A common repeat element has proliferated throughout the mtDNA and ptDNA of this chlamydomonadalean green alga, resulting in the unprecedented situation whereby these two distinct organelle genomes are largely made up of nearly identical sequences. In this short update to the work on H. lacustris, I highlight another chlamydomonadalean species (Stephanosphaera pluvialis) for which matching repeats have spread throughout its organelle genomes (but to a lesser degree than in H. lacustris). What's more, the organelle repeats from S. pluvialis are similar to those from H. lacustris, suggesting that they have a shared origin, and perhaps existed in the mtDNA and ptDNA of the most recent common ancestor of these two species. However, my examination of organelle genomes from other close relatives of H. lacustris and S. pluvialis did not uncover further compelling examples of common organelle repeat elements, meaning that the evolutionary history of these repeats might be more complicated than initially thought.
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Affiliation(s)
- David Roy Smith
- Department of Biology, University of Western Ontario, London, ON, Canada
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