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Liu M, Hu SY, Li M, Sun H, Yuan ML. Comparative mitogenomic analysis provides evolutionary insights into Formica (Hymenoptera: Formicidae). PLoS One 2024; 19:e0302371. [PMID: 38857223 PMCID: PMC11164359 DOI: 10.1371/journal.pone.0302371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 04/02/2024] [Indexed: 06/12/2024] Open
Abstract
Formica is a large genus in the family Formicidae with high diversity in its distribution, morphology, and physiology. To better understand evolutionary characteristics of Formica, the complete mitochondrial genomes (mitogenomes) of two Formica species were determined and a comparative mitogenomic analysis for this genus was performed. The two newly sequenced Formica mitogenomes each included 37 typical mitochondrial genes and a large non-coding region (putative control region), as observed in other Formica mitogenomes. Base composition, gene order, codon usage, and tRNA secondary structure were well conserved among Formica species, whereas diversity in sequence size and structural characteristics was observed in control regions. We also observed several conserved motifs in the intergenic spacer regions. These conserved genomic features may be related to mitochondrial function and their highly conserved physiological constraints, while the diversity of the control regions may be associated with adaptive evolution among heterogenous habitats. A negative AT-skew value on the majority chain was presented in each of Formica mitogenomes, indicating a reversal of strand asymmetry in base composition. Strong codon usage bias was observed in Formica mitogenomes, which was predominantly determined by nucleotide composition. All 13 mitochondrial protein-coding genes of Formica species exhibited molecular signatures of purifying selection, as indicated by the ratio of non-synonymous substitutions to synonymous substitutions being less than 1 for each protein-coding gene. Phylogenetic analyses based on mitogenomic data obtained fairly consistent phylogenetic relationships, except for two Formica species that had unstable phylogenetic positions, indicating mitogenomic data are useful for constructing phylogenies of ants. Beyond characterizing two additional Formica mitogenomes, this study also provided some key evolutionary insights into Formica.
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Affiliation(s)
- Min Liu
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou, Gansu, China
- National Demonstration Center for Experimental Grassland Science Education, Lanzhou University, Lanzhou, Gansu, China
- College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, China
| | - Shi-Yun Hu
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou, Gansu, China
- National Demonstration Center for Experimental Grassland Science Education, Lanzhou University, Lanzhou, Gansu, China
- College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, China
| | - Min Li
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou, Gansu, China
- College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, China
| | - Hao Sun
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou, Gansu, China
- National Demonstration Center for Experimental Grassland Science Education, Lanzhou University, Lanzhou, Gansu, China
- College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, China
| | - Ming-Long Yuan
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu, China
- Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Lanzhou, Gansu, China
- National Demonstration Center for Experimental Grassland Science Education, Lanzhou University, Lanzhou, Gansu, China
- College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou, Gansu, China
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Vangalis V, Likhotkin I, Knop M, Typas MA, Papaioannou IA. Starvation-induced cell fusion and heterokaryosis frequently escape imperfect allorecognition systems in an asexual fungal pathogen. BMC Biol 2021; 19:169. [PMID: 34429100 PMCID: PMC8385987 DOI: 10.1186/s12915-021-01101-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 07/16/2021] [Indexed: 01/02/2023] Open
Abstract
Background Asexual fungi include important pathogens of plants and other organisms, and their effective management requires understanding of their evolutionary dynamics. Genetic recombination is critical for adaptability and could be achieved via heterokaryosis — the co-existence of genetically different nuclei in a cell resulting from fusion of non-self spores or hyphae — and the parasexual cycle in the absence of sexual reproduction. Fusion between different strains and establishment of viable heterokaryons are believed to be rare due to non-self recognition systems. Here, we investigate the extent and mechanisms of cell fusion and heterokaryosis in the important asexual plant pathogen Verticillium dahliae. Results We used live-cell imaging and genetic complementation assays of tagged V. dahliae strains to analyze the extent of non-self vegetative fusion, heterokaryotic cell fate, and nuclear behavior. An efficient CRISPR/Cas9-mediated system was developed to investigate the involvement of autophagy in heterokaryosis. Under starvation, non-self fusion of germinating spores occurs frequently regardless of the previously assessed vegetative compatibility of the partners. Supposedly “incompatible” fusions often establish viable heterokaryotic cells and mosaic mycelia, where nuclei can engage in fusion or transfer of genetic material. The molecular machinery of autophagy has a protective function against the destruction of “incompatible” heterokaryons. Conclusions We demonstrate an imperfect function of somatic incompatibility systems in V. dahliae. These systems frequently tolerate the establishment of heterokaryons and potentially the initiation of the parasexual cycle even between strains that were previously regarded as “incompatible.” Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01101-5.
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Affiliation(s)
- Vasileios Vangalis
- Department of Genetics and Biotechnology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Ilya Likhotkin
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany
| | - Michael Knop
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany.,German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Milton A Typas
- Department of Genetics and Biotechnology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
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Vangalis V, Knop M, Typas MA, Papaioannou IA. Establishment of conidial fusion in the asexual fungus Verticillium dahliae as a useful system for the study of non-sexual genetic interactions. Curr Genet 2021; 67:471-485. [PMID: 33582843 PMCID: PMC8139932 DOI: 10.1007/s00294-021-01157-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/11/2021] [Accepted: 01/22/2021] [Indexed: 02/07/2023]
Abstract
Cell-to-cell fusion is a fundamental biological process across the tree of life. In filamentous fungi, somatic fusion (or anastomosis) is required for the normal development of their syncytial hyphal networks, and it can initiate non-sexual genetic exchange processes, such as horizontal genetic transfer and the parasexual cycle. Although these could be important drivers of the evolution of asexual fungi, this remains a largely unexplored possibility due to the lack of suitable resources for their study in these puzzling organisms. We thus aimed at the characterization of cell fusion in the important asexual fungus Verticillium dahliae via Conidial Anastomosis Tubes (CATs), which can be useful for the analysis of parasexuality. We optimized appropriate procedures for their highly reproducible quantification and live-cell imaging, which were used to characterize their physiology and cell biology, and to start elucidating their underlying genetic machinery. Formation of CATs was shown to depend on growth conditions and require functional Fus3 and Slt2 MAP kinases, as well as the NADPH oxidase NoxA, whereas the GPCR Ste2 and the mating-type protein MAT1-2-1 were dispensable. We show that nuclei and other organelles can migrate through CATs, which often leads to the formation of transient dikaryons. Their nuclei have possible windows of opportunity for genetic interaction before degradation of one by a presumably homeostatic mechanism. We establish here CAT-mediated fusion in V. dahliae as an experimentally convenient system for the cytological analysis of fungal non-sexual genetic interactions. We expect that it will facilitate the dissection of sexual alternatives in asexual fungi.
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Affiliation(s)
- Vasileios Vangalis
- Department of Genetics and Biotechnology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Michael Knop
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany.,German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Milton A Typas
- Department of Genetics and Biotechnology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
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Vangalis V, Papaioannou IA, Markakis EA, Knop M, Typas MA. Hex1, the Major Component of Woronin Bodies, Is Required for Normal Development, Pathogenicity, and Stress Response in the Plant Pathogenic Fungus Verticillium dahliae. J Fungi (Basel) 2020; 6:jof6040344. [PMID: 33297524 PMCID: PMC7762394 DOI: 10.3390/jof6040344] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 11/27/2020] [Accepted: 12/03/2020] [Indexed: 12/31/2022] Open
Abstract
Woronin bodies are membrane-bound organelles of filamentous ascomycetes that mediate hyphal compartmentalization by plugging septal pores upon hyphal damage. Their major component is the peroxisomal protein Hex1, which has also been implicated in additional cellular processes in fungi. Here, we analyzed the Hex1 homolog of Verticillium dahliae, an important asexual plant pathogen, and we report its pleiotropic involvement in fungal growth, physiology, stress response, and pathogenicity. Alternative splicing of the Vdhex1 gene can lead to the production of two Hex1 isoforms, which are structurally similar to their Neurospora crassa homolog. We show that VdHex1 is targeted to the septum, consistently with its demonstrated function in sealing hyphal compartments to prevent excessive cytoplasmic bleeding upon injury. Furthermore, our investigation provides direct evidence for significant contributions of Hex1 in growth and morphogenesis, as well as in asexual reproduction capacity. We discovered that Hex1 is required both for normal responses to osmotic stress and factors that affect the cell wall and plasma-membrane integrity, and for normal resistance to oxidative stress and reactive oxygen species (ROS) homeostasis. The Vdhex1 mutant exhibited diminished ability to colonize and cause disease on eggplant. Overall, we show that Hex1 has fundamentally important multifaceted roles in the biology of V. dahliae.
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Affiliation(s)
- Vasileios Vangalis
- Department of Genetics & Biotechnology, Faculty of Biology, National and Kapodistrian University of Athens, 15784 Athens, Greece;
| | - Ioannis A. Papaioannou
- Center for Molecular Biology, Heidelberg University (ZMBH), 69120 Heidelberg, Germany; (I.A.P.); (M.K.)
| | - Emmanouil A. Markakis
- Laboratory of Mycology, Department of Viticulture, Vegetable Crops, Floriculture and Plant Protection, Institute of Olive Tree, Subtropical Crops and Viticulture, N.A.G.R.E.F., Hellenic Agricultural Organization—DEMETER, 71307 Heraklion, Crete, Greece;
| | - Michael Knop
- Center for Molecular Biology, Heidelberg University (ZMBH), 69120 Heidelberg, Germany; (I.A.P.); (M.K.)
- German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Milton A. Typas
- Department of Genetics & Biotechnology, Faculty of Biology, National and Kapodistrian University of Athens, 15784 Athens, Greece;
- Correspondence:
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Verticillium Wilt of Olive and its Control: What Did We Learn during the Last Decade? PLANTS 2020; 9:plants9060735. [PMID: 32545292 PMCID: PMC7356185 DOI: 10.3390/plants9060735] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/09/2020] [Accepted: 06/09/2020] [Indexed: 02/06/2023]
Abstract
Verticillium (Verticillium dahliae Kleb.) wilt is one of the most devastating diseases affecting olive (Olea europaea L. subsp. europaea var. europaea) cultivation. Its effective control strongly relies on integrated management strategies. Olive cultivation systems are experiencing important changes (e.g., high-density orchards, etc.) aiming at improving productivity. The impact of these changes on soil biology and the incidence/severity of olive pests and diseases has not yet been sufficiently evaluated. A comprehensive understanding of the biology of the pathogen and its populations, the epidemiological factors contributing to exacerbating the disease, the underlying mechanisms of tolerance/resistance, and the involvement of the olive-associated microbiota in the tree's health is needed. This knowledge will be instrumental to developing more effective control measures to confront the disease in regions where the pathogen is present, or to exclude it from V. dahliae-free areas. This review compiles the most recent advances achieved to understand the olive-V. dahliae interaction as well as measures to control the disease. Aspects such as the molecular basis of the host-pathogen interaction, the identification of new biocontrol agents, the implementation of "-omics" approaches to unravel the basis of disease tolerance, and the utilization of remote sensing technology for the early detection of pathogen attacks are highlighted.
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Papaioannou IA, Dimopoulou CD, Typas MA. "Cryptic" group-I introns in the nuclear SSU-rRNA gene of Verticillium dahliae. Curr Genet 2013; 60:135-48. [PMID: 24258678 DOI: 10.1007/s00294-013-0417-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 10/24/2013] [Accepted: 11/06/2013] [Indexed: 11/30/2022]
Abstract
Group-I introns are widespread--though irregularly distributed--in eukaryotic organisms, and they have been extensively used for discrimination and phylogenetic analyses. Within the Verticillium genus, which comprises important phytopathogenic fungi, a group-I intron was previously identified in the SSU-rRNA (18S) gene of only V. longisporum. In this work, we aimed at elucidating the SSU-located intron distribution in V. dahliae and other Verticillium species, and the assessment of heterogeneity regarding intron content among rDNA repeats of fungal strains. Using conserved PCR primers for the amplification of the SSU gene, a structurally similar novel intron (sub-group IC1) was detected in only a few V. dahliae isolates. However, when intron-specific primers were used for the screening of a diverse collection of Verticillium isolates that originally failed to produce intron-containing SSU amplicons, most were found to contain one or both intron types, at variable rDNA repeat numbers. This marked heterogeneity was confirmed with qRT-PCR by testing rDNA copy numbers (varying from 39 to 70 copies per haploid genome) and intron copy ratios in selected isolates. Our results demonstrate that (a) IC1 group-I introns are not specific to V. longisporum within the Verticillium genus, (b) V. dahliae isolates of vegetative compatibility groups (VCGs) 4A and 6, which bear the novel intron at most of their rDNA repeats, are closely related, and (c) there is considerable intra-genomic heterogeneity for the presence or absence of introns among the ribosomal repeats. These findings underline that distributions of introns in the highly heterogeneous repetitive rDNA complex should always be verified with sensitive methods to avoid misleading conclusions for the phylogeny of fungi and other organisms.
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Affiliation(s)
- Ioannis A Papaioannou
- Department of Genetics and Biotechnology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece
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