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Feng X, Zheng J, Irisarri I, Yu H, Zheng B, Ali Z, de Vries S, Keller J, Fürst-Jansen JMR, Dadras A, Zegers JMS, Rieseberg TP, Dhabalia Ashok A, Darienko T, Bierenbroodspot MJ, Gramzow L, Petroll R, Haas FB, Fernandez-Pozo N, Nousias O, Li T, Fitzek E, Grayburn WS, Rittmeier N, Permann C, Rümpler F, Archibald JM, Theißen G, Mower JP, Lorenz M, Buschmann H, von Schwartzenberg K, Boston L, Hayes RD, Daum C, Barry K, Grigoriev IV, Wang X, Li FW, Rensing SA, Ben Ari J, Keren N, Mosquna A, Holzinger A, Delaux PM, Zhang C, Huang J, Mutwil M, de Vries J, Yin Y. Genomes of multicellular algal sisters to land plants illuminate signaling network evolution. Nat Genet 2024; 56:1018-1031. [PMID: 38693345 PMCID: PMC11096116 DOI: 10.1038/s41588-024-01737-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 03/25/2024] [Indexed: 05/03/2024]
Abstract
Zygnematophyceae are the algal sisters of land plants. Here we sequenced four genomes of filamentous Zygnematophyceae, including chromosome-scale assemblies for three strains of Zygnema circumcarinatum. We inferred traits in the ancestor of Zygnematophyceae and land plants that might have ushered in the conquest of land by plants: expanded genes for signaling cascades, environmental response, and multicellular growth. Zygnematophyceae and land plants share all the major enzymes for cell wall synthesis and remodifications, and gene gains shaped this toolkit. Co-expression network analyses uncover gene cohorts that unite environmental signaling with multicellular developmental programs. Our data shed light on a molecular chassis that balances environmental response and growth modulation across more than 600 million years of streptophyte evolution.
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Affiliation(s)
- Xuehuan Feng
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Jinfang Zheng
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE, USA
- Zhejiang Lab, Hangzhou, China
| | - Iker Irisarri
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
- Campus Institute Data Science, University of Goettingen, Goettingen, Germany
- Section Phylogenomics, Centre for Molecular biodiversity Research, Leibniz Institute for the Analysis of Biodiversity Change, Zoological Museum Hamburg, Hamburg, Germany
| | - Huihui Yu
- University of Nebraska-Lincoln, Center for Plant Science Innovation, Lincoln, NE, USA
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Science, Yunnan, China
| | - Bo Zheng
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Zahin Ali
- Nanyang Technological University, School of Biological Sciences, Singapore, Singapore
| | - Sophie de Vries
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Jean Keller
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS, INP Toulouse, Castanet-Tolosan, France
| | - Janine M R Fürst-Jansen
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Armin Dadras
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Jaccoline M S Zegers
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Tim P Rieseberg
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Amra Dhabalia Ashok
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Tatyana Darienko
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Maaike J Bierenbroodspot
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany
| | - Lydia Gramzow
- University of Jena, Matthias Schleiden Institute/Genetics, Jena, Germany
| | - Romy Petroll
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Fabian B Haas
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
- Department of Algal Development and Evolution, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Noe Fernandez-Pozo
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
- Institute for Mediterranean and Subtropical Horticulture 'La Mayora', Málaga, Spain
| | - Orestis Nousias
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Tang Li
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Elisabeth Fitzek
- Computational Biology, Department of Biology, Center for Biotechnology, Bielefeld University, Bielefeld, Germany
| | - W Scott Grayburn
- Northern Illinois University, Molecular Core Lab, Department of Biological Sciences, DeKalb, IL, USA
| | - Nina Rittmeier
- University of Innsbruck, Department of Botany, Research Group Plant Cell Biology, Innsbruck, Austria
| | - Charlotte Permann
- University of Innsbruck, Department of Botany, Research Group Plant Cell Biology, Innsbruck, Austria
| | - Florian Rümpler
- University of Jena, Matthias Schleiden Institute/Genetics, Jena, Germany
| | - John M Archibald
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Günter Theißen
- University of Jena, Matthias Schleiden Institute/Genetics, Jena, Germany
| | - Jeffrey P Mower
- University of Nebraska-Lincoln, Center for Plant Science Innovation, Lincoln, NE, USA
| | - Maike Lorenz
- University of Goettingen, Albrecht-von-Haller-Institute for Plant Sciences, Experimental Phycology and Culture Collection of Algae at Goettingen University, Goettingen, Germany
| | - Henrik Buschmann
- University of Applied Sciences Mittweida, Faculty of Applied Computer Sciences and Biosciences, Section Biotechnology and Chemistry, Molecular Biotechnology, Mittweida, Germany
| | - Klaus von Schwartzenberg
- Universität Hamburg, Institute of Plant Science and Microbiology, Microalgae and Zygnematophyceae Collection Hamburg and Aquatic Ecophysiology and Phycology, Hamburg, Germany
| | - Lori Boston
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | - Richard D Hayes
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Chris Daum
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kerrie Barry
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Igor V Grigoriev
- Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Xiyin Wang
- North China University of Science and Technology, Tangshan, China
| | - Fay-Wei Li
- Boyce Thompson Institute, Ithaca, NY, USA
- Plant Biology Section, Cornell University, Ithaca, NY, USA
| | - Stefan A Rensing
- Plant Cell Biology, Department of Biology, University of Marburg, Marburg, Germany
- University of Freiburg, Centre for Biological Signalling Studies (BIOSS), Freiburg, Germany
| | - Julius Ben Ari
- The Hebrew University of Jerusalem, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Rehovot, Israel
| | - Noa Keren
- The Hebrew University of Jerusalem, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Rehovot, Israel
| | - Assaf Mosquna
- The Hebrew University of Jerusalem, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Rehovot, Israel
| | - Andreas Holzinger
- University of Innsbruck, Department of Botany, Research Group Plant Cell Biology, Innsbruck, Austria
| | - Pierre-Marc Delaux
- Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS, INP Toulouse, Castanet-Tolosan, France
| | - Chi Zhang
- University of Nebraska-Lincoln, Center for Plant Science Innovation, Lincoln, NE, USA
- University of Nebraska-Lincoln, School of Biological Sciences, Lincoln, NE, USA
| | - Jinling Huang
- Department of Biology, East Carolina University, Greenville, NC, USA
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China
| | - Marek Mutwil
- Nanyang Technological University, School of Biological Sciences, Singapore, Singapore
| | - Jan de Vries
- Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Goettingen, Goettingen, Germany.
- Campus Institute Data Science, University of Goettingen, Goettingen, Germany.
- University of Goettingen, Goettingen Center for Molecular Biosciences, Goettingen, Germany.
| | - Yanbin Yin
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE, USA.
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Yang H, Ni Y, Zhang X, Li J, Chen H, Liu C. The mitochondrial genomes of Panax notoginseng reveal recombination mediated by repeats associated with DNA replication. Int J Biol Macromol 2023; 252:126359. [PMID: 37619687 DOI: 10.1016/j.ijbiomac.2023.126359] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 08/07/2023] [Accepted: 08/14/2023] [Indexed: 08/26/2023]
Abstract
Panax notoginseng is one of the most valuable medicinal species. However, its mitochondrial genome has not been reported yet. We aimed to determine the mitogenome sequence of P. notoginseng. We de novo assembled the mitogenome with Illumina short reads and Nanopore long reads. The mitochondrial genome of P. notoginseng has a multipartite structure consisting of interconversion between a "master circle" and numerous "subgenomic circles" through recombinations mediated by 64 pairs of repetitive sequences. Among the multipartite structure, seven subgenomic circles were best supported. Six of the seven subgenomic circles shared an 852 bp conserved fragment. The complete mitogenome of P. notoginseng was 662,479 bp long including 34 mitochondrial protein-coding genes (PCGs), three rRNA, and 19 tRNA genes. We identified 166 microsatellite repeats and 26 long-tandem repeats. Phylogenetic analysis resolved a tree that was mostly congruent with the phylogeny of Apiales species described in the APG IV system and the tree built with the chloroplast genome sequences. A total of 12 mitochondrial plastid DNA fragments were identified. Lastly, we predicted 591C-to-U RNA editing sites in the coding regions of mitochondrial PCGs. The mitochondrial genome will lay the foundation for understanding the evolution of Panax species.
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Affiliation(s)
- Heyu Yang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, PR China
| | - Yang Ni
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, PR China
| | - Xinyi Zhang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, PR China
| | - Jingling Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, PR China
| | - Haimei Chen
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, PR China.
| | - Chang Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, PR China.
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Sanyal SK, Sharma K, Bisht D, Sharma S, Kateriya S, Pandey GK. Role of calcium sensor protein module CBL-CIPK in abiotic stress and light signaling responses in green algae. Int J Biol Macromol 2023; 237:124163. [PMID: 36965564 DOI: 10.1016/j.ijbiomac.2023.124163] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/14/2023] [Accepted: 03/20/2023] [Indexed: 03/27/2023]
Abstract
Ca2+ signaling is an important biological process that enable to perceive and communicate information in the cell. Our current understanding of the signaling system suggests that plants and animals have certain differences in signal-sensing mechanisms. The Ca2+-mediated CBL-CIPK module has emerged as a major sensor responder network for Ca2+ signaling and has been speculated to be involved in plant terrestrial life adaptation. This module has previously been reported in Archaeplastids, Chromalveolates, and Excavates. In our experimental analysis of Chlamydomonas reinhardtii CBLs, we proved that the CrCBL1 protein interacts with Phototropin and Channelrhodopsin, and the expression of CrCBLs is modulated by light. Further analysis using chlorophyte and streptophyte algal sequences allowed us to identify the differences that have evolved in CBL and CIPK proteins since plants have progressed from aquatic to terrestrial habitats. Moreover, an investigation of Klebsormidium CBL and CIPK genes led us to know that they are abiotic stress stimuli-responsive, indicating that their role was defined very early during terrestrial adaptations. Structure-based prediction and Ca2+-binding assays indicated that the KnCBL1 protein in Klebsormidium showed a typical Ca2+-binding pocket. In summary, the results of this study suggest that these stress-responsive proteins enable crosstalk between Ca2+ and light signaling pathways very early during plant adaptation from aquatic to terrestrial habitats.
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Affiliation(s)
- Sibaji K Sanyal
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India; Laboratory of Optobiotechnology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Komal Sharma
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India; Laboratory of Optobiotechnology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Diksha Bisht
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India
| | - Sunita Sharma
- Laboratory of Optobiotechnology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Suneel Kateriya
- Laboratory of Optobiotechnology, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India.
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Zumkeller S, Knoop V. Categorizing 161 plant (streptophyte) mitochondrial group II introns into 29 families of related paralogues finds only limited links between intron mobility and intron-borne maturases. BMC Ecol Evol 2023; 23:5. [PMID: 36915058 PMCID: PMC10012718 DOI: 10.1186/s12862-023-02108-y] [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: 09/20/2022] [Accepted: 02/27/2023] [Indexed: 03/14/2023] Open
Abstract
Group II introns are common in the two endosymbiotic organelle genomes of the plant lineage. Chloroplasts harbor 22 positionally conserved group II introns whereas their occurrence in land plant (embryophyte) mitogenomes is highly variable and specific for the seven major clades: liverworts, mosses, hornworts, lycophytes, ferns, gymnosperms and flowering plants. Each plant group features "signature selections" of ca. 20-30 paralogues from a superset of altogether 105 group II introns meantime identified in embryophyte mtDNAs, suggesting massive intron gains and losses along the backbone of plant phylogeny. We report on systematically categorizing plant mitochondrial group II introns into "families", comprising evidently related paralogues at different insertion sites, which may even be more similar than their respective orthologues in phylogenetically distant taxa. Including streptophyte (charophyte) algae extends our sampling to 161 and we sort 104 streptophyte mitochondrial group II introns into 25 core families of related paralogues evidently arising from retrotransposition events. Adding to discoveries of only recently created intron paralogues, hypermobile introns and twintrons, our survey led to further discoveries including previously overlooked "fossil" introns in spacer regions or e.g., in the rps8 pseudogene of lycophytes. Initially excluding intron-borne maturase sequences for family categorization, we added an independent analysis of maturase phylogenies and find a surprising incongruence between intron mobility and the presence of intron-borne maturases. Intriguingly, however, we find that several examples of nuclear splicing factors meantime characterized simultaneously facilitate splicing of independent paralogues now placed into the same intron families. Altogether this suggests that plant group II intron mobility, in contrast to their bacterial counterparts, is not intimately linked to intron-encoded maturases.
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Affiliation(s)
- Simon Zumkeller
- IZMB, Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Volker Knoop
- IZMB, Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115, Bonn, Germany.
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Yang J, Ling C, Zhang H, Hussain Q, Lyu S, Zheng G, Liu Y. A Comparative Genomics Approach for Analysis of Complete Mitogenomes of Five Actinidiaceae Plants. Genes (Basel) 2022; 13:genes13101827. [PMID: 36292711 PMCID: PMC9601400 DOI: 10.3390/genes13101827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 10/01/2022] [Accepted: 10/01/2022] [Indexed: 11/04/2022] Open
Abstract
Actinidiaceae, an economically important plant family, includes the Actinidia, Clematoclethra and Saurauia genus. Kiwifruit, with remarkably high vitamin C content, is an endemic species widely distributed in China with high economic value. Although many Actinidiaceae chloroplast genomes have been reported, few complete mitogenomes of Actinidiaceae have been studied. Here, complete circular mitogenomes of the four kiwifruit species and Saurauia tristyla were assembled. Codon usage, sequence repeats, RNA editing, gene transfers, selective pressure, and phylogenetic relationships in the four kiwifruit species and S. tristyla were comparatively analyzed. This research will contribute to the study of phylogenetic relationships within Actiniaceae and molecular barcoding in kiwifruit.
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Affiliation(s)
- Jun Yang
- College of Horticulture, Anhui Agriculture University, Hefei 350002, China
| | - Chengcheng Ling
- College of Horticulture, Anhui Agriculture University, Hefei 350002, China
| | - Huamin Zhang
- College of Horticulture, Anhui Agriculture University, Hefei 350002, China
| | - Quaid Hussain
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 666 Wusu Street, Hangzhou 311300, China
| | - Shiheng Lyu
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, 666 Wusu Street, Hangzhou 311300, China
| | - Guohua Zheng
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Correspondence: (G.Z.); (Y.L.)
| | - Yongsheng Liu
- College of Horticulture, Anhui Agriculture University, Hefei 350002, China
- Correspondence: (G.Z.); (Y.L.)
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Zheng J, Meinhardt LW, Goenaga R, Zhang D, Yin Y. The chromosome-level genome of dragon fruit reveals whole-genome duplication and chromosomal co-localization of betacyanin biosynthetic genes. HORTICULTURE RESEARCH 2021; 8:63. [PMID: 33750805 PMCID: PMC7943767 DOI: 10.1038/s41438-021-00501-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 05/05/2023]
Abstract
Dragon fruits are tropical fruits economically important for agricultural industries. As members of the family of Cactaceae, they have evolved to adapt to the arid environment. Here we report the draft genome of Hylocereus undatus, commercially known as the white-fleshed dragon fruit. The chromosomal level genome assembly contains 11 longest scaffolds corresponding to the 11 chromosomes of H. undatus. Genome annotation of H. undatus found ~29,000 protein-coding genes, similar to Carnegiea gigantea (saguaro). Whole-genome duplication (WGD) analysis revealed a WGD event in the last common ancestor of Cactaceae followed by extensive genome rearrangements. The divergence time between H. undatus and C. gigantea was estimated to be 9.18 MYA. Functional enrichment analysis of orthologous gene clusters (OGCs) in six Cactaceae plants found significantly enriched OGCs in drought resistance. Fruit flavor-related functions were overrepresented in OGCs that are significantly expanded in H. undatus. The H. undatus draft genome also enabled the discovery of carbohydrate and plant cell wall-related functional enrichment in dragon fruits treated with trypsin for a longer storage time. Lastly, genes of the betacyanin (a red-violet pigment and antioxidant with a very high concentration in dragon fruits) biosynthetic pathway were found to be co-localized on a 12 Mb region of one chromosome. The consequence may be a higher efficiency of betacyanin biosynthesis, which will need experimental validation in the future. The H. undatus draft genome will be a great resource to study various cactus plants.
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Affiliation(s)
- Jinfang Zheng
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska, Lincoln, NE, 68588, USA
| | | | - Ricardo Goenaga
- Tropical Agriculture Research Station, USDA-ARS, Puerto Rico, PR, USA
| | - Dapeng Zhang
- Sustainable Perennial Crops Lab, USDA-ARS, Beltsville, MD, USA.
| | - Yanbin Yin
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska, Lincoln, NE, 68588, USA.
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Feng X, Holzinger A, Permann C, Anderson D, Yin Y. Characterization of Two Zygnema Strains ( Zygnema circumcarinatum SAG 698-1a and SAG 698-1b) and a Rapid Method to Estimate Nuclear Genome Size of Zygnematophycean Green Algae. FRONTIERS IN PLANT SCIENCE 2021; 12:610381. [PMID: 33643345 PMCID: PMC7902510 DOI: 10.3389/fpls.2021.610381] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/15/2021] [Indexed: 05/07/2023]
Abstract
Zygnematophyceae green algae (ZGA) have been shown to be the closest relatives of land plants. Three nuclear genomes (Spirogloea muscicola, Mesotaenium endlicherianum, and Penium margaritaceum) of ZGA have been recently published, and more genomes are underway. Here we analyzed two Zygnema circumcarinatum strains SAG 698-1a (mating +) and SAG 698-1b (mating -) and found distinct cell sizes and other morphological differences. The molecular identities of the two strains were further investigated by sequencing their 18S rRNA, psaA and rbcL genes. These marker genes of SAG 698-1a were surprisingly much more similar to Z. cylindricum (SAG 698-2) than to SAG 698-1b. Phylogenies of these marker genes also showed that SAG 698-1a and SAG 698-1b were well separated into two different Zygnema clades, where SAG 698-1a was clustered with Z. cylindricum, while SAG 698-1b was clustered with Z. tunetanum. Additionally, physiological parameters like ETRmax values differed between SAG 698-1a and SAG 698-1b after 2 months of cultivation. The de-epoxidation state (DEPS) of the xanthophyll cycle pigments also showed significant differences. Surprisingly, the two strains could not conjugate, and significantly differed in the thickness of the mucilage layer. Additionally, ZGA cell walls are highly enriched with sticky and acidic polysaccharides, and therefore the widely used plant nuclear extraction protocols do not work well in ZGA. Here, we also report a fast and simple method, by mechanical chopping, for efficient nuclear extraction in the two SAG strains. More importantly, the extracted nuclei were further used for nuclear genome size estimation of the two SAG strains by flow cytometry (FC). To confirm the FC result, we have also used other experimental methods for nuclear genome size estimation of the two strains. Interestingly, the two strains were found to have very distinct nuclear genome sizes (313.2 ± 2.0 Mb in SAG 698-1a vs. 63.5 ± 0.5 Mb in SAG 698-1b). Our multiple lines of evidence strongly indicate that SAG 698-1a possibly had been confused with SAG 698-2 prior to 2005, and most likely represents Z. cylindricum or a closely related species.
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Affiliation(s)
- Xuehuan Feng
- Department of Food Science and Technology, Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, NE, United States
| | | | | | - Dirk Anderson
- Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Yanbin Yin
- Department of Food Science and Technology, Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, NE, United States
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