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Zhang TT, Xu X, Lv M. Measurement and prediction of the Aspergillus niger spore detachment from a vesicle unit subjected to air-blowing. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:168714. [PMID: 38007138 DOI: 10.1016/j.scitotenv.2023.168714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/17/2023] [Accepted: 11/18/2023] [Indexed: 11/27/2023]
Abstract
Detachment of fungal spores from growing colonies results in human exposure. Thus far, the distribution of the binding forces of the spores in a fungal unit is unknown, so that precise prediction of the spores detachment is quite challenging. This investigation used centrifugal separation to measure the binding forces of the spores. Aspergillus niger (A. niger) colonies on a culture plate were placed in a centrifuge, the detached spores were counted, and this number was used to obtain the distribution of binding forces. Next, the air-blowing of an A. niger unit was modeled by computational fluid dynamics (CFD). A spore was judged to be detached if the air-imposed drag force was greater than the binding force. For model validation, the predicted spore detachment ratios were compared with the ratios measured in a wind tunnel test. The results revealed that the binding forces of the spores obeyed the log-normal distribution. The binding forces of the distal spores from colonies with a growth age of 66 h ranged from 0 nN to 4.0 nN and had a mean of 0.65 nN. The CFD modeling predicted the detachment ratios of the distal spores with good accuracy.
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Affiliation(s)
- Tengfei Tim Zhang
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China; School of Civil Engineering, Dalian University of Technology, Dalian, China.
| | - Xinzi Xu
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Mengqiang Lv
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China.
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2
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Bucknell AH, McDonald MC. That's no moon, it's a Starship: Giant transposons driving fungal horizontal gene transfer. Mol Microbiol 2023; 120:555-563. [PMID: 37434470 DOI: 10.1111/mmi.15118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 07/13/2023]
Abstract
To date, most reports of horizontal gene transfer (HGT) in fungi rely on genome sequence data and are therefore an indirect measure of HGT after the event has occurred. However, a novel group of class II-like transposons known as Starships may soon alter this status quo. Starships are giant transposable elements that carry dozens of genes, some of which are host-beneficial, and are linked to many recent HGT events in the fungal kingdom. These transposons remain active and mobile in many fungal genomes and their transposition has recently been shown to be driven by a conserved tyrosine-recombinase called 'Captain'. This perspective explores some of the remaining unanswered questions about how these Starship transposons move, both within a genome and between different species. We seek to outline several experimental approaches that can be used to identify the genes essential for Starship-mediated HGT and draw links to other recently discovered giant transposons outside of the fungal kingdom.
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Affiliation(s)
- Angus H Bucknell
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Megan C McDonald
- School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
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Yang X, Zhang F, Yang Y, Zhou F, Boonmee S, Xiao W, Yang X. Conidia Fusion: A Mechanism for Fungal Adaptation to Nutrient-Poor Habitats. J Fungi (Basel) 2023; 9:755. [PMID: 37504743 PMCID: PMC10381365 DOI: 10.3390/jof9070755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/13/2023] [Accepted: 07/14/2023] [Indexed: 07/29/2023] Open
Abstract
Conidia fusion (CF) is a commonly observed structure in fungi. However, it has not been systematically studied. This study examined 2457 strains of nematode-trapping fungi (NTF) to explore the species specificity, physiological period, and physiological significance of CF. The results demonstrated that only six species of Arthrobotrys can form CF among the sixty-five tested NTF species. The studies on the model species Arthrobotrys oligospora (DL228) showed that CF occurred in both shed and unshed plus mature and immature conidia. Additionally, the conidia fusion rate (CFR) increased significantly with the decrease of nutrient concentration in habitats. The studies on the conidia fusion body (CFB) produced by A. oligospora (DL228) revealed that the more conidia contained in the CFB, the faster and denser the mycelia of the CFB germinated in weak nutrient medium and soil plates. On the one hand, rapid mycelial extension is beneficial for the CFB to quickly find new nutrient sources in habitats with uneven nutrient distribution. On the other hand, dense mycelium increases the contact area with the environment, improving the nutrient absorption efficiency, which is conducive to improving the survival rate of conidia in the weak nutrient environment. In addition, all species that form CF produce smaller conidia. Based on this observation, CF may be a strategy to balance the defects (nutrient deficiency) caused by conidia miniaturization.
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Affiliation(s)
- Xinju Yang
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali 671003, China
| | - Fa Zhang
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali 671003, China
- Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand
- School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand
| | - Yaoquan Yang
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali 671003, China
| | - Faping Zhou
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali 671003, China
| | - Saranyaphat Boonmee
- Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand
- School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand
| | - Wen Xiao
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali 671003, China
- Collaborative Innovation Center for Biodiversity and Conservation in the Three Parallel Rivers Region of China, Dali 671003, China
- The Provincial Innovation Team of Biodiversity Conservation and Utility of the Three Parallel Rivers Region, Dali University, Dali 671003, China
- Yunling Back-and-White Snub-Nosed Monkey Observation and Research Station of Yunnan Province, Dali 671003, China
- Key Laboratory of Yunnan State Education Department on Er'hai Lake Basin Protection and the Sustainable Development Research, Dali University, Dali 671003, China
| | - Xiaoyan Yang
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali 671003, China
- Collaborative Innovation Center for Biodiversity and Conservation in the Three Parallel Rivers Region of China, Dali 671003, China
- The Provincial Innovation Team of Biodiversity Conservation and Utility of the Three Parallel Rivers Region, Dali University, Dali 671003, China
- Yunling Back-and-White Snub-Nosed Monkey Observation and Research Station of Yunnan Province, Dali 671003, China
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Liu X, Li B, Cai J, Shi T, Yang Y, Feng Y, Huang G. Whole genome resequencing reveal patterns of genetic variation within Colletotrichum acutatum species complex from rubber trees in China. Fungal Genet Biol 2023; 167:103801. [PMID: 37196569 DOI: 10.1016/j.fgb.2023.103801] [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: 09/08/2022] [Revised: 04/04/2023] [Accepted: 04/27/2023] [Indexed: 05/19/2023]
Abstract
The Colletotrichum acutatum species complex possesses a diverse number of important traits, such as a wide host range and host preference, different modes of reproduction, and different strategies of host infection. Research using comparative genomics has attempted to find correlations between these traits. Here, we used multi-locus techniques and gene genealogical concordance analysis to investigate the phylogenetic relationships and taxonomic status of the Colletotrichum acutatum species complex using field isolates obtained from rubber trees. The results revealed that the dominant species was C. australisinense, followed by C. bannaense, while strain YNJH17109 was identified as C. laticiphilum. The taxonomic status of strains YNLC510 and YNLC511 was undetermined. Using whole-genome single nucleotide polymorphism data to analyze population structure, 18 strains of C. australisinense were subsequently divided into four populations, one of which was derived from an admixture of two populations. In addition, the strains LD1687, GD1628, and YNLC516, did not belong to any populations, and were considered to be admixtures of two or more populations. A split decomposition network analysis also provided evidence for genetic recombination within Colletotrichum acutatum species complex from rubber trees in China. Overall, a weak phylogeographic sub-structure was observed. Analysis also revealed significant differences in morphological characters and levels of virulence between populations.
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Affiliation(s)
- Xianbao Liu
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences (CATAS), Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, PR China
| | - Boxun Li
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences (CATAS), Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, PR China
| | - Jimiao Cai
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences (CATAS), Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, PR China
| | - Tao Shi
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences (CATAS), Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, PR China
| | - Yang Yang
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences (CATAS), Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, PR China
| | - Yanli Feng
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences (CATAS), Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, PR China
| | - Guixiu Huang
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences (CATAS), Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture, Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, PR China.
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Fleißner A, Oostlander AG, Well L. Highly conserved, but highly specific: Somatic cell-cell fusion in filamentous fungi. Curr Opin Cell Biol 2022; 79:102140. [PMID: 36347130 DOI: 10.1016/j.ceb.2022.102140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 11/06/2022]
Abstract
The development of ascomycete fungal colonies involves cell-cell fusion at different growth stages. In the model fungus Neurospora crassa, communication of two fusing cells is mediated by an unusual signaling mechanism, in which the two partners take turns in signal sending and receiving. In recent years, the molecular basis of this unusual cellular behavior has started to unfold, indicating the presence of an excitable signaling network. New evidence suggests that this communication system is highly conserved in ascomycete fungi and, unexpectedly, even mediates interspecies interactions. At the same time, intricate allorecognition mechanisms were identified, which prevent the fusion of genetically unlike individuals. These observations suggest that signal specificity during fungal social behavior has not evolved on the level of signals and receptors, but is achieved at downstream checkpoints. Despite growing insight into the molecular mechanisms controlling self and non-self fungal interactions, their role in natural environments remains largely unknown.
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Affiliation(s)
- André Fleißner
- Institut für Genetik, Technische Universität Braunschweig, Braunschweig, Germany.
| | - Anne G Oostlander
- Institut für Genetik, Technische Universität Braunschweig, Braunschweig, Germany
| | - Lucas Well
- Institut für Genetik, Technische Universität Braunschweig, Braunschweig, Germany
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6
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Liu X, Li B, Cai J, Yang Y, Feng Y, Huang G. Characterization and necrosis-inducing activity of necrosis- and ethylene-inducing peptide 1-like proteins from Colletotrichum australisinense, the causative agent of rubber tree anthracnose. Front Microbiol 2022; 13:969479. [PMID: 36110300 PMCID: PMC9468550 DOI: 10.3389/fmicb.2022.969479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/11/2022] [Indexed: 11/30/2022] Open
Abstract
Colletotrichum australisinense, a member of the Colletotrichum acutatum species complex, is an important pathogen causing rubber tree anthracnose. Genome-wide comparative analysis showed this species complex contains more genes encoding necrosis- and ethylene-inducing peptide 1-like proteins (NLPs) than other Colletotrichum species complexes, but little is known about their necrosis-inducing roles in host. The aim of this study was to analyze NLPs number and type in C. australisinense, and characterize their necrosis-inducing activity in host or non-host. According to phylogenetic relationship, conserved the cysteine residues and the heptapeptide motif (GHRHDWE), 11 NLPs were identified and classified into three types. Five of the eleven NLPs were evaluated for necrosis-inducing activity. CaNLP4 (type 1) could not induce necrosis in host or non-host plants. By contrast, both CaNLP5 and CaNLP9 (type 1) induced necrosis in host and non-host plants, and necrosis-inducing activity was strongest for CaNLP9. CaNLP10 (type 2) and CaNLP11 (type 3) induced necrosis in host but not non-host plants. Substitution of key amino acid residues essential for necrosis induction activity led to loss of CaNLP4 activity. Structural characterization of CaNLP5 and CaNLP9 may explain differences in necrosis-inducing activity. We evaluated the expression of genes coding CaNLP by reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qRT-PCR) at different time-points after pathogen infection. It was found that genes encoding CaNLPs with different activities exhibited significantly different expression patterns. The results demonstrate that CaNLPs are functionally and spatially distinct, and may play different but important roles in C. australisinense pathogenesis.
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Polyphasic Systematics of the Fungicolous Genus Cladobotryum Based on Morphological, Molecular and Metabolomics Data. J Fungi (Basel) 2022; 8:jof8080877. [PMID: 36012865 PMCID: PMC9409756 DOI: 10.3390/jof8080877] [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: 07/29/2022] [Revised: 08/16/2022] [Accepted: 08/17/2022] [Indexed: 11/16/2022] Open
Abstract
(1) Background: Species of the anamorphic genus Cladobotryum, are known for their fungicolous lifestyle, making them important mycopathogens in fungiculture. Many morphological, ecological, and molecular phylogenetic studies of the genus have been done to date, but taxonomic uncertainties and challenges still remain. Fungal secondary metabolites, being vastly diverse, are utilised as an extra tool in fungal systematics. Despite being studied for their potentially bioactive compounds, Cladobotryum species are insufficiently investigated regarding metabolomics. (2) Methods: The aim of this study is the identification of Greek strains of Cladobotryum by integrating morphological data, ITS-based phylogeny, and 1H NMR-based metabolomics into a polyphasic approach. (3) Results: Twenty-three strains, isolated from sporophores of macromycetes inhabiting diverse Greek ecosystems, were morphologically identified as Cladobotryum apiculatum, C. fungicola, C. mycophilum, C. varium, C. verticillatum, and Hypomyces rosellus (anamorph C. dendroides), whereas seven strains, which produced red-pigmented metabolites, presented an ambiguous taxonomic position at the species level. Molecular phylogenetics and metabolomics corroborated the morphological findings. (4) Conclusions: Thorough morphological study, ITS region-based phylogeny, and NMR-based metabolomics contribute complementarily to resolving the genus Cladobotryum systematics.
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Hyphal Fusions Enable Efficient Nutrient Distribution in Colletotrichum graminicola Conidiation and Symptom Development on Maize. Microorganisms 2022; 10:microorganisms10061146. [PMID: 35744664 PMCID: PMC9231406 DOI: 10.3390/microorganisms10061146] [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: 03/15/2022] [Revised: 05/25/2022] [Accepted: 05/30/2022] [Indexed: 02/01/2023] Open
Abstract
Hyphal and germling fusion is a common phenomenon in ascomycetous fungi. Due to the formed hyphal network, this process enables a coordinated development as well as an interaction with plant hosts and efficient nutrient distribution. Recently, our laboratory work demonstrated a positive correlation between germling fusion and the formation of penetrating hyphopodia on maize leaves outgoing from Colletotrichum graminicola oval conidia. To investigate the probable interconnectivity of these processes, we generated a deletion mutant in Cgso, in which homologs are essential for cellular fusion in other fungal species. However, hyphopodia development was not affected, indicating that both processes are not directly connected. Instead, we were able to link the cellular fusion defect in ∆Cgso to a decreased formation of asexual fruiting bodies of C. graminicola on the leaves. The monitoring of a fluorescent-labelled autophagy marker, eGFP-CgAtg8, revealed a high autophagy activity in the hyphae surrounding the acervuli. These results support the hypothesis that the efficient nutrient transport of degraded cellular material by hyphal fusions enables proper acervuli maturation and, therefore, symptom development on the leaves.
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A dialogue-like cell communication mechanism is conserved in filamentous ascomycete fungi and mediates interspecies interactions. Proc Natl Acad Sci U S A 2022; 119:e2112518119. [PMID: 35286209 PMCID: PMC8944665 DOI: 10.1073/pnas.2112518119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
This study reveals that a dialogue-like communication mechanism, which mediates cell–cell fusion in filamentous fungi, is a conserved complex trait. It allows the communication and behavioral coordination of cells of distantly related species and mediates their mutual attraction and subsequent physical contact, although interspecies fusion does not occur. Through the activation of this signaling machinery, one species can reprogram the developmental program of the other fungus. These data promote our understanding of microbial communication, illustrate the mechanism of repurposing of existing building blocks in cellular evolution, revive the hypothesis of vegetative fusion as an avenue of horizontal gene transfer in fungi, and establish the idea of developmental reprogramming as a tool for controlling fungi. In many filamentous fungi, germinating spores cooperate by fusing into supracellular structures, which develop into the mycelial colony. In the model fungus Neurospora crassa, this social behavior is mediated by an intriguing mode of communication, in which two fusing cells take turns in signal sending and receiving. Here we show that this dialogue-like cell communication mechanism is highly conserved in distantly related fungal species and mediates interspecies interactions. In mixed populations, cells of N. crassa and the phytopathogenic gray mold Botrytis cinerea coordinate their behavior over a spatial distance and establish physical contact. Subsequent cell–cell fusion is, however, restricted to germlings of the same species, indicating that species specificity of germling fusion has evolved not on the level of the signal/receptor but at subsequent levels of the fusion process. In B. cinerea, fusion and infectious growth are mutually exclusive cellular programs. Remarkably, the presence of N. crassa can reprogram this behavior and induce fusion of the gray mold on plant surfaces, potentially weakening its pathogenic potential. In a third fungal species, the nematode-trapping fungus Arthrobotrys flagrans, the conserved signaling mechanism mediates vegetative fusion within mycelial colonies but has also been repurposed for the formation of nematode-catching traps. In summary, this study identified the cell dialogue mechanism as a conserved complex trait and revealed that even distantly related fungi possess a common molecular language, which promotes cellular contact formation across species borders.
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Abstract
Fungi exhibit an enormous variety of morphologies, including yeast colonies, hyphal mycelia, and elaborate fruiting bodies. This diversity arises through a combination of polar growth, cell division, and cell fusion. Because fungal cells are nonmotile and surrounded by a protective cell wall that is essential for cell integrity, potential fusion partners must grow toward each other until they touch and then degrade the intervening cell walls without impacting cell integrity. Here, we review recent progress on understanding how fungi overcome these challenges. Extracellular chemoattractants, including small peptide pheromones, mediate communication between potential fusion partners, promoting the local activation of core cell polarity regulators to orient polar growth and cell wall degradation. However, in crowded environments, pheromone gradients can be complex and potentially confusing, raising the question of how cells can effectively find their partners. Recent findings suggest that the cell polarity circuit exhibits searching behavior that can respond to pheromone cues through a remarkably flexible and effective strategy called exploratory polarization.
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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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Liu Y, Tang J, Zhou Y. Identification and Description of a New Pathogen Causing Flower Dry Rot on Passiflora edulis in China. PLANT DISEASE 2021; 105:1967-1975. [PMID: 33289411 DOI: 10.1094/pdis-10-20-2130-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Passiflora edulis Sims (passion fruit) is an economically important fruit crop. However, a new flower dry rot has occurred in orchards located in Zhanjiang, China, and has led to serious production loss. Its disease incidence is approximately 30 to 40%. A total of 221 isolates of Fusarium sp. were obtained from samples of three types of symptomatic flowers. Three representative single-spore isolates (PaB-1, PaB-2, and PaB-3) from each type were used for pathogenicity tests, multilocus phylogenetic analyses, and morphological descriptions. Pathogenicity tests of buds of 5-month-old P. edulis plants showed symptoms similar to those observed in nature, and Koch's postulates were achieved. By comparing 36 typical species from the FUSARIUM-ID database, multilocus phylogenetic analyses showed that the sequences of TEF1, RPB2, and ITS of these isolates belong to the Incarnatum clade of the F. incarnatum-equiseti species complex (FIESC-17-a) with an independent branch. Therefore, the pathogenic isolates were identified as F. pernambucanum (FIESC-17-a). Moreover, in this study, the conidial anastomosis tubes were first observed in the FIESC. This is the first report of flower dry rot on P. edulis caused by F. pernambucanum. Further studies should be performed to determine effective disease management strategies.
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Affiliation(s)
- Yuelian Liu
- Guangdong Ocean University, Zhanjiang, Guangdong 524088, China
| | - Jianrong Tang
- Guangdong Ocean University, Zhanjiang, Guangdong 524088, China
| | - Yuhan Zhou
- Guangdong Ocean University, Zhanjiang, Guangdong 524088, China
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Differential Physiological Prerequisites and Gene Expression Profiles of Conidial Anastomosis Tube and Germ Tube Formation in Colletotrichum gloeosporioides. J Fungi (Basel) 2021; 7:jof7070509. [PMID: 34202250 PMCID: PMC8306183 DOI: 10.3390/jof7070509] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 02/07/2023] Open
Abstract
The conidia of a hemibiotrophic fungus, Colletotrichum gloeosporioides, can conventionally form a germ tube (GT) and develop into a fungal colony. Under certain conditions, they tend to get connected through a conidial anastomosis tube (CAT) to share the nutrients. CAT fusion is believed to be responsible for the generation of genetic variations in few asexual fungi, which appears problematic for effective fungal disease management. The physiological and molecular requirements underlying the GT formation versus CAT fusion remained underexplored. In the present study, we have deciphered the physiological prerequisites for GT formation versus CAT fusion in C. gloeosporioides. GT formation occurred at a high frequency in the presence of nutrients, while CAT fusion was found to be higher in the absence of nutrients. Younger conidia were found to form GT efficiently, while older conidia preferentially formed CAT. Whole transcriptome analysis of GT and CAT revealed highly differential gene expression profiles, wherein 11,050 and 9786 genes were differentially expressed during GT formation and CAT fusion, respectively. A total of 1567 effector candidates were identified; out of them, 102 and 100 were uniquely expressed during GT formation and CAT fusion, respectively. Genes coding for cell wall degrading enzymes, germination, hyphal growth, host-fungus interaction, and virulence were highly upregulated during GT formation. Meanwhile, genes involved in stress response, cell wall remodeling, membrane transport, cytoskeleton, cell cycle, and cell rescue were highly upregulated during CAT fusion. To conclude, the GT formation and CAT fusion were found to be mutually exclusive processes, requiring differential physiological conditions and sets of DEGs in C. gloeosporioides. This study will help in understanding the basic CAT biology in emerging fungal model species of the genus Colletotrichum.
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Csata E, Billen J, Barbu-Tudoran L, Markó B. Inside Pandora's box: Development of the lethal myrmecopathogenic fungus Pandora formicae within its ant host. FUNGAL ECOL 2021. [DOI: 10.1016/j.funeco.2020.101022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Mehta N, Baghela A. Quorum sensing-mediated inter-specific conidial anastomosis tube fusion between Colletotrichum gloeosporioides and C. siamense. IMA Fungus 2021; 12:7. [PMID: 33789776 PMCID: PMC8015167 DOI: 10.1186/s43008-021-00058-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 02/21/2021] [Indexed: 02/07/2023] Open
Abstract
Many plant pathogenic filamentous fungi undergo fusion of conidia through conidial anastomosis tubes (CATs), which is believed to facilitate horizontal gene transfer between species. We discovered a remarkable inter-specific CAT fusion between two important plant fungal pathogens Colletotrichum gloeosporioides and C. siamense. In an invitro assay, under no selection pressure, the inter-specific CAT fusion was preferred with higher frequency (25% ± 5%) than intra-specific CAT fusion (11% ± 3.6%). Different stages of CAT fusion viz. CAT induction, homing, and fusion were observed during this inter-specific CAT fusion. The CAT fusion was found to be higher in absence of nutrients and under physiological stresses. This CAT fusion involved a quorum sensing phenomenon, wherein the CAT induction was dependent on conidial density and the putative quorum sensing molecule was extractable in chloroform. Movement of nuclei, mitochondria, and lipid droplets were observed during the CAT fusion. Post CAT fusion, the resulting conidia gave rise to putative heterokaryotic progenies with variable colony characteristics as compared to their parental strains. Few heterokaryons showed variable AFLP banding pattern compared to their parental strains, thereby suggesting a possible genetic exchange between the two species through CAT fusion. The heterokaryotic progenies exhibited varied fitness under different stress conditions. Our study illustrated a possible role of inter-specific CAT fusion in generation of genetic and phenotypic diversity in these fungal pathogens.
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Affiliation(s)
- Nikita Mehta
- National Fungal Culture Collection of India (NFCCI), Biodiversity and Palaeobiology Group, MACS-Agharkar Research Institute, G.G. Agarkar Road, Pune, 411004, India.,Savitribai Phule Pune University, Pune, 411007, India
| | - Abhishek Baghela
- National Fungal Culture Collection of India (NFCCI), Biodiversity and Palaeobiology Group, MACS-Agharkar Research Institute, G.G. Agarkar Road, Pune, 411004, India. .,Savitribai Phule Pune University, Pune, 411007, India.
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16
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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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17
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Weichert M, Herzog S, Robson SA, Brandt R, Priegnitz BE, Brandt U, Schulz S, Fleißner A. Plasma Membrane Fusion Is Specifically Impacted by the Molecular Structure of Membrane Sterols During Vegetative Development of Neurospora crassa. Genetics 2020; 216:1103-1116. [PMID: 33046504 PMCID: PMC7768248 DOI: 10.1534/genetics.120.303623] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/11/2020] [Indexed: 02/07/2023] Open
Abstract
Cell-to-cell fusion is crucial for the development and propagation of most eukaryotic organisms. Despite this importance, the molecular mechanisms mediating this process are only poorly understood in biological systems. In particular, the step of plasma membrane merger and the contributing proteins and physicochemical factors remain mostly unknown. Earlier studies provided the first evidence of a role of membrane sterols in cell-to-cell fusion. By characterizing different ergosterol biosynthesis mutants of the fungus Neurospora crassa, which accumulate different ergosterol precursors, we show that the structure of the sterol ring system specifically affects plasma membrane merger during the fusion of vegetative spore germlings. Genetic analyses pinpoint this defect to an event prior to engagement of the fusion machinery. Strikingly, this effect is not observed during sexual fusion, suggesting that the specific sterol precursors do not generally block membrane merger, but rather impair subcellular processes exclusively mediating fusion of vegetative cells. At a colony-wide level, the altered structure of the sterol ring system affects a subset of differentiation processes, including vegetative sporulation and steps before and after fertilization during sexual propagation. Together, these observations corroborate the notion that the accumulation of particular sterol precursors has very specific effects on defined cellular processes rather than nonspecifically disturbing membrane functioning. Given the phenotypic similarities of the ergosterol biosynthesis mutants of N. crassa during vegetative fusion and of Saccharomyces cerevisiae cells undergoing mating, our data support the idea that yeast mating is evolutionarily and mechanistically more closely related to vegetative than sexual fusion of filamentous fungi.
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Affiliation(s)
- Martin Weichert
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Stephanie Herzog
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Sarah-Anne Robson
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Raphael Brandt
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Bert-Ewald Priegnitz
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Ulrike Brandt
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Stefan Schulz
- Institut für Organische Chemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - André Fleißner
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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18
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Yuan BH, Li H, Liu L, Du XH. Successful induction and recognition of conidiation, conidial germination and chlamydospore formation in pure culture of Morchella. Fungal Biol 2020; 125:285-293. [PMID: 33766307 DOI: 10.1016/j.funbio.2020.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 11/19/2020] [Accepted: 11/23/2020] [Indexed: 01/17/2023]
Abstract
Morels, fungi from the genus Morchella, are popular edible mushrooms. However, little knowledge of their asexual reproduction and inaccessible pure mitospores hamper illumination of their life cycle. Herein, we successfully induced conidiation, conidial germination and chlamydospore formation in pure culture of Morchella sextelata. Conidiation proceeded via four morphologically distinct stages: development of the conidiophore stalk, stalk branching, phialide differentiation, and conidium production. Terminal and intercalary chlamydospores were formed on conidial hyphae. The development of conidiophores occurred earlier, with more conidia produced, in cross-mating cultures than in single-spore cultures. Mature conidia were spherical and 2.5-8 μm in diameter, with a vast majority (nearly 99%) 2.5-5 μm in diameter. Each conidium contained one to three nuclei (80.2% conidia contained one nucleus, 19.1% contained two nuclei, and 0.7% contained three nuclei). The conidial nucleus diameter was 1-2 μm. The nuclear mitosis in detached conidia that was observed may benefit their colony initiation. Additionally, morel conidia formed conidial anastomosis tubes. Conidia (mitospores) likely not only function as spermatia, but also as reproductive propagules in Morchella. Further research is imperative to elucidate the relationship between the conidia and chlamydospores, and their unique function in the morel life cycle.
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Affiliation(s)
- Bin-Hong Yuan
- College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Huan Li
- College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Lu Liu
- College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Xi-Hui Du
- College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China.
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19
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Complexity of Brassica oleracea- Alternaria brassicicola Susceptible Interaction Reveals Downregulation of Photosynthesis at Ultrastructural, Transcriptional, and Physiological Levels. Cells 2020; 9:cells9102329. [PMID: 33092216 PMCID: PMC7593931 DOI: 10.3390/cells9102329] [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: 10/03/2020] [Revised: 10/17/2020] [Accepted: 10/18/2020] [Indexed: 01/23/2023] Open
Abstract
Black spot disease, caused by Alternaria brassicicola in Brassica species, is one of the most devastating diseases all over the world, especially since there is no known fully resistant Brassica cultivar. In this study, the visualization of black spot disease development on Brassica oleracea var. capitata f. alba (white cabbage) leaves and subsequent ultrastructural, molecular and physiological investigations were conducted. Inter- and intracellular hyphae growth within leaf tissues led to the loss of host cell integrity and various levels of organelle disintegration. Severe symptoms of chloroplast damage included the degeneration of chloroplast envelope and grana, and the loss of electron denseness by stroma at the advanced stage of infection. Transcriptional profiling of infected leaves revealed that photosynthesis was the most negatively regulated biological process. However, in infected leaves, chlorophyll and carotenoid content did not decrease until 48 hpi, and several chlorophyll a fluorescence parameters, such as photosystem II quantum yield (Fv/Fm), non-photochemical quenching (NPQ), or plant vitality parameter (Rdf) decreased significantly at 24 and 48 hpi compared to control leaves. Our results indicate that the initial stages of interaction between B. oleracea and A. brassicicola are not uniform within an inoculation site and show a complexity of host responses and fungal attempts to overcome host cell defense mechanisms. The downregulation of photosynthesis at the early stage of this susceptible interaction suggests that it may be a part of a host defense strategy, or, alternatively, that chloroplasts are targets for the unknown virulence factor(s) of A. brassicicola. However, the observed decrease of photosynthetic efficiency at the later stages of infection is a result of the fungus-induced necrotic lesion expansion.
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20
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Mela AP, Rico-Ramírez AM, Glass NL. Syncytia in Fungi. Cells 2020; 9:cells9102255. [PMID: 33050028 PMCID: PMC7600787 DOI: 10.3390/cells9102255] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/27/2020] [Accepted: 09/29/2020] [Indexed: 12/27/2022] Open
Abstract
Filamentous fungi typically grow as interconnected multinucleate syncytia that can be microscopic to many hectares in size. Mechanistic details and rules that govern the formation and function of these multinucleate syncytia are largely unexplored, including details on syncytial morphology and the regulatory controls of cellular and molecular processes. Recent discoveries have revealed various adaptations that enable fungal syncytia to accomplish coordinated behaviors, including cell growth, nuclear division, secretion, communication, and adaptation of the hyphal network for mixing nuclear and cytoplasmic organelles. In this review, we highlight recent studies using advanced technologies to define rules that govern organizing principles of hyphal and colony differentiation, including various aspects of nuclear and mitochondrial cooperation versus competition. We place these findings into context with previous foundational literature and present still unanswered questions on mechanistic aspects, function, and morphological diversity of fungal syncytia across the fungal kingdom.
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Affiliation(s)
- Alexander P. Mela
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; (A.P.M.); (A.M.R.-R.)
| | - Adriana M. Rico-Ramírez
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; (A.P.M.); (A.M.R.-R.)
| | - N. Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; (A.P.M.); (A.M.R.-R.)
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Correspondence:
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21
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Abstract
Most genomes within the species complex of Fusarium oxysporum are organized into two compartments: the core chromosomes (CCs) and accessory chromosomes (ACs). As opposed to CCs, which are conserved and vertically transmitted to carry out essential housekeeping functions, lineage- or strain-specific ACs are believed to be initially horizontally acquired through unclear mechanisms. These two genomic compartments are different in terms of gene density, the distribution of transposable elements, and epigenetic markers. Although common in eukaryotes, the functional importance of ACs is uniquely emphasized among fungal species, specifically in relationship to fungal pathogenicity and their adaptation to diverse hosts. With a focus on the cross-kingdom fungal pathogen F. oxysporum, this review provides a summary of the differences between CCs and ACs based on current knowledge of gene functions, genome structures, and epigenetic signatures, and explores the transcriptional crosstalk between the core and accessory genomes.
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22
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Francisco CS, Zwyssig MM, Palma-Guerrero J. The role of vegetative cell fusions in the development and asexual reproduction of the wheat fungal pathogen Zymoseptoria tritici. BMC Biol 2020; 18:99. [PMID: 32782023 PMCID: PMC7477884 DOI: 10.1186/s12915-020-00838-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 07/27/2020] [Indexed: 12/23/2022] Open
Abstract
Background The ability of fungal cells to undergo cell-to-cell communication and anastomosis, the process of vegetative hyphal fusion, allows them to maximize their overall fitness. Previous studies in a number of fungal species have identified the requirement of several signaling pathways for anastomosis, including the so far best characterized soft (So) gene, and the MAPK pathway components MAK-1 and MAK-2 of Neurospora crassa. Despite the observations of hyphal fusions’ involvement in pathogenicity and host adhesion, the connection between cell fusion and fungal lifestyles is still unclear. Here, we address the role of anastomosis in fungal development and asexual reproduction in Zymoseptoria tritici, the most important fungal pathogen of wheat in Europe. Results We show that Z. tritici undergoes self-fusion between distinct cellular structures, and its mechanism is dependent on the initial cell density. Contrary to other fungi, cell fusion in Z. tritici only resulted in cytoplasmic mixing but not in multinucleated cell formation. The deletion of the So orthologous ZtSof1 disrupted cell-to-cell communication affecting both hyphal and germling fusion. We show that Z. tritici mutants for MAPK-encoding ZtSlt2 (orthologous to MAK-1) and ZtFus3 (orthologous to MAK-2) genes also failed to undergo anastomosis, demonstrating the functional conservation of this signaling mechanism across species. Additionally, the ΔZtSof1 mutant was severely impaired in melanization, suggesting that the So gene function is related to melanization. Finally, we demonstrated that anastomosis is dispensable for pathogenicity, but essential for the pycnidium development, and its absence abolishes the asexual reproduction of Z. tritici. Conclusions We demonstrate the role for ZtSof1, ZtSlt2, and ZtFus3 in cell fusions of Z. tritici. Cell fusions are essential for different aspects of the Z. tritici biology, and the ZtSof1 gene is a potential target to control septoria tritici blotch (STB) disease.
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Affiliation(s)
| | - Maria Manuela Zwyssig
- Plant Pathology Group, Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland
| | - Javier Palma-Guerrero
- Plant Pathology Group, Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland. .,New Address: Department of Biointeractions and Crop Protection, Rothamsted Research, Harpenden, UK.
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23
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Gonçalves AP, Glass NL. Fungal social barriers: to fuse, or not to fuse, that is the question. Commun Integr Biol 2020; 13:39-42. [PMID: 32313605 PMCID: PMC7159315 DOI: 10.1080/19420889.2020.1740554] [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: 01/19/2020] [Revised: 03/02/2020] [Accepted: 03/02/2020] [Indexed: 12/15/2022] Open
Abstract
Cell fusion takes place in all domains of life and contributes greatly to the formation of complex multicellular structures. In particular, many fungi, such as the filamentous Neurospora crassa, rely on conspecific somatic cell fusion to drive the unicellular-to-multicellular transition and formation of the interconnected mycelial syncytium. This can, however, lead to the transmission of infectious elements and deleterious genotypes that have a negative impact on the organismal fitness. Accumulating evidence obtained from natural populations suggests that N. crassa has evolved various self/non-self or allorecognition systems to avoid fusion between genetically non-identical spores or hyphae at all costs. Here we present an overview of the recent advances made in the field of fungal allorecognition, describe its genetic basis, and comment on its evolutionary meaning. These data pinpoint the multilayered complexity of the cooperative social behaviors undertaken by a model eukaryotic microbe.
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Affiliation(s)
- A Pedro Gonçalves
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - N Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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24
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Frantzeskakis L, Di Pietro A, Rep M, Schirawski J, Wu CH, Panstruga R. Rapid evolution in plant-microbe interactions - a molecular genomics perspective. THE NEW PHYTOLOGIST 2020; 225:1134-1142. [PMID: 31134629 DOI: 10.1111/nph.15966] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 05/14/2019] [Indexed: 06/09/2023]
Abstract
Rapid (co-)evolution at multiple timescales is a hallmark of plant-microbe interactions. The mechanistic basis for the rapid evolution largely rests on the features of the genomes of the interacting partners involved. Here, we review recent insights into genomic characteristics and mechanisms that enable rapid evolution of both plants and phytopathogens. These comprise fresh insights in allelic series of matching pairs of resistance and avirulence genes, the generation of novel pathogen effectors, the recently recognised small RNA warfare, and genomic aspects of secondary metabolite biosynthesis. In addition, we discuss the putative contributions of permissive host environments, transcriptional plasticity and the role of ploidy on the interactions. We conclude that the means underlying the rapid evolution of plant-microbe interactions are multifaceted and depend on the particular nature of each interaction.
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Affiliation(s)
| | - Antonio Di Pietro
- Departamento de Genética and Campus de Excelencia Agroalimentario (ceiA3), Universidad de Córdoba, 14071, Córdoba, Spain
| | - Martijn Rep
- Faculty of Science, Swammerdam Institute for Life Sciences, University of Amsterdam, PO Box 94215, 1090 GE, Amsterdam, the Netherlands
| | - Jan Schirawski
- Microbial Genetics, Institute of Applied Microbiology, RWTH Aachen University, Aachen, Germany
| | - Chih-Hang Wu
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Ralph Panstruga
- Unit of Plant Molecular Cell Biology, Institute for Biology I, RWTH Aachen University, Worringerweg 1, Aachen, 52056, Germany
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25
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Gonçalves AP, Chow KM, Cea-Sánchez S, Glass NL. WHI-2 Regulates Intercellular Communication via a MAP Kinase Signaling Complex. Front Microbiol 2020; 10:3162. [PMID: 32038591 PMCID: PMC6987382 DOI: 10.3389/fmicb.2019.03162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/31/2019] [Indexed: 01/15/2023] Open
Abstract
The formation of the fungal mycelial network is facilitated by somatic cell fusion of germinating asexual spores (or germlings). Neurospora crassa germlings in close proximity display chemotropic growth that is dependent upon an intracellular network of mitogen-activated protein kinase (MAPK) signaling cascades. Approximately 80 genes involved in intercellular communication and fusion have been identified, including three mutants with similar morphological phenotypes: Δwhi-2, Δcsp-6, and Δamph-1. Here we show that WHI-2 localizes to the cell periphery and regulates endocytosis, mitochondrial organization, sporulation, and cell fusion. WHI-2 was required to transduce signals through a conserved MAPK pathway (NRC-1/MEK-2/MAK-2) and target transcription factors (PP-1/ADV-1). The amph-1 locus encodes a Bin/Amphiphysin/Rvs domain-containing protein and mis-expression of whi-2 compensated for the cell fusion and endocytosis deficiencies of a Δamph-1 mutant. The csp-6 locus encodes a haloacid dehalogenase phosphatase whose activity was essential for cell fusion. Although fusion-deficient with themselves, cells that lacked whi-2, csp-6, or amph-1 showed a low frequency of chemotropic interactions with wild type cells. We hypothesize that WHI-2 could be important for signal perception during chemotropic interactions via a role in endocytosis.
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Affiliation(s)
- A Pedro Gonçalves
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Karen M Chow
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Sara Cea-Sánchez
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
| | - N Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
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26
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Abstract
Fungi can fuse with other individuals to enable cooperative growth, although this process is restricted by certain self/non-self recognition systems. A novel layer of compatibility has now been discovered, acting at the stage of germling cell wall fusion, showing the remarkable complexity of allorecognition in fungi.
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Affiliation(s)
- Paul S Dyer
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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27
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Nordzieke DE, Sanken A, Antelo L, Raschke A, Deising HB, Pöggeler S. Specialized infection strategies of falcate and oval conidia of Colletotrichum graminicola. Fungal Genet Biol 2019; 133:103276. [PMID: 31550526 DOI: 10.1016/j.fgb.2019.103276] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 09/19/2019] [Accepted: 09/19/2019] [Indexed: 01/12/2023]
Abstract
For many filamentous fungi with pathogenic lifestyles, the presence of distinct asexual conidia has been described. However, the role of these spore types remains mostly obscure. Colletotrichum graminicola is a hemibiotrophic filamentous fungus, causing anthracnose on maize plants with a high potential of epidemic disease spreading. C. graminicola generates two types of conidia. Falcate shaped conidia formed in necrotic lesions on maize tissues are able to generate appressoria with high efficiency and are considered key disease spreading propagules. The second conidia type, the smaller oval conidia, is formed in the vascular system of the infected plant, probably causing the distribution of the disease in planta. Barely any knowledge exists about how these conidia are able to exhibit their specific functions in the life cycle and pathogenicity of C. graminicola. Here, we show that germlings derived from both falcate and oval conidia differ in the secretion of a germination inhibitor and signals for germling fusion. Germination experiments combined with HPLC and mass spectrometry analyses revealed that germination of falcate conidia is regulated by the self-inhibitor mycosporine-glutamine, whereas this compound is absent from oval conidia cultures. Additionally, germlings derived from oval conidia undergo germling fusions at high frequencies and are able to induce such a fusion when co-incubated with falcate conidia. Falcate conidia germlings alone, however, were never observed to fuse. Plant infection experiments showed a positive correlation between germling fusions and efficient leaf infection by oval conidia. However, this correlation was not observed for infection by falcate conidia. Together, our findings reveal significant differences of two types of conidia derived from the same pathogenic fungus with distinct roles in pathogenesis.
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Affiliation(s)
- Daniela E Nordzieke
- Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics, Georg August University Göttingen, Grisebachstrasse 8, DE-37081 Göttingen, Germany.
| | - Alina Sanken
- Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics, Georg August University Göttingen, Grisebachstrasse 8, DE-37081 Göttingen, Germany
| | - Luis Antelo
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), Erwin-Schrödinger-Strasse 56, DE-67663 Kaiserslautern, Germany
| | - Anja Raschke
- Institute for Agricultural and Nutritional Sciences, Faculty for Natural Sciences III, Martin-Luther-University Halle-Wittenberg, Betty-Heimann-Strasse 3, DE-06120 Halle (Saale), Germany
| | - Holger B Deising
- Institute for Agricultural and Nutritional Sciences, Faculty for Natural Sciences III, Martin-Luther-University Halle-Wittenberg, Betty-Heimann-Strasse 3, DE-06120 Halle (Saale), Germany
| | - Stefanie Pöggeler
- Department of Genetics of Eukaryotic Microorganisms, Institute of Microbiology and Genetics, Georg August University Göttingen, Grisebachstrasse 8, DE-37081 Göttingen, Germany
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28
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Inducible Cell Fusion Permits Use of Competitive Fitness Profiling in the Human Pathogenic Fungus Aspergillus fumigatus. Antimicrob Agents Chemother 2018; 63:AAC.01615-18. [PMID: 30397071 DOI: 10.1128/aac.01615-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/31/2018] [Indexed: 12/24/2022] Open
Abstract
Antifungal agents directed against novel therapeutic targets are required for treating invasive, chronic, and allergic Aspergillus infections. Competitive fitness profiling technologies have been used in a number of bacterial and yeast systems to identify druggable targets; however, the development of similar systems in filamentous fungi is complicated by the fact that they undergo cell fusion and heterokaryosis. Here, we demonstrate that cell fusion in Aspergillus fumigatus under standard culture conditions is not predominately constitutive, as with most ascomycetes, but can be induced by a range of extracellular stressors. Using this knowledge, we have developed a barcode-free genetic profiling system that permits high-throughput parallel determination of strain fitness in a collection of diploid A. fumigatus mutants. We show that heterozygous cyp51A and arf2 null mutants have reduced fitness in the presence of itraconazole and brefeldin A, respectively, and a heterozygous atp17 null mutant is resistant to brefeldin A.
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Velvet domain protein VosA represses the zinc cluster transcription factor SclB regulatory network for Aspergillus nidulans asexual development, oxidative stress response and secondary metabolism. PLoS Genet 2018; 14:e1007511. [PMID: 30044771 PMCID: PMC6078315 DOI: 10.1371/journal.pgen.1007511] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 08/06/2018] [Accepted: 06/22/2018] [Indexed: 12/30/2022] Open
Abstract
The NF-κB-like velvet domain protein VosA (viability of spores) binds to more than 1,500 promoter sequences in the filamentous fungus Aspergillus nidulans. VosA inhibits premature induction of the developmental activator gene brlA, which promotes asexual spore formation in response to environmental cues as light. VosA represses a novel genetic network controlled by the sclB gene. SclB function is antagonistic to VosA, because it induces the expression of early activator genes of asexual differentiation as flbC and flbD as well as brlA. The SclB controlled network promotes asexual development and spore viability, but is independent of the fungal light control. SclB interactions with the RcoA transcriptional repressor subunit suggest additional inhibitory functions on transcription. SclB links asexual spore formation to the synthesis of secondary metabolites including emericellamides, austinol as well as dehydroaustinol and activates the oxidative stress response of the fungus. The fungal VosA-SclB regulatory system of transcription includes a VosA control of the sclB promoter, common and opposite VosA and SclB control functions of fungal development and several additional regulatory genes. The relationship between VosA and SclB illustrates the presence of a convoluted surveillance apparatus of transcriptional control, which is required for accurate fungal development and the linkage to the appropriate secondary metabolism. Velvet domain proteins of filamentous fungi are structurally similar to Rel-homology domains of mammalian NF-κB proteins. Velvet and NF-κB proteins control regulatory circuits of downstream transcriptional networks for cellular differentiation, survival and stress responses. Velvet proteins interconnect developmental programs with secondary metabolism in fungi. The velvet protein VosA binds to more than ten percent of the Aspergillus nidulans promoters and is important for the spatial and temporal control of asexual spore formation from conidiophores. A novel VosA-dependent genetic network has been identified and is controlled by the zinc cluster protein SclB. Although zinc cluster proteins constitute one of the most abundant classes of transcription factors in fungi, only a small amount is characterized. SclB is a repression target of VosA and both transcription factors are part of a mutual control in the timely adjusted choreography of asexual sporulation in A. nidulans. SclB acts at the interphase of asexual development and secondary metabolism and interconnects both programs with an adequate oxidative stress response. This study underlines the complexity of different hierarchical levels of the fungal velvet protein transcriptional network for developmental programs and interconnected secondary metabolism.
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Kurian SM, Di Pietro A, Read ND. Live-cell imaging of conidial anastomosis tube fusion during colony initiation in Fusarium oxysporum. PLoS One 2018; 13:e0195634. [PMID: 29734342 PMCID: PMC5937734 DOI: 10.1371/journal.pone.0195634] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 03/26/2018] [Indexed: 01/07/2023] Open
Abstract
Fusarium oxysporum exhibits conidial anastomosis tube (CAT) fusion during colony initiation to form networks of conidial germlings. Here we determined the optimal culture conditions for this fungus to undergo CAT fusion between microconidia in liquid medium. Extensive high resolution, confocal live-cell imaging was performed to characterise the different stages of CAT fusion, using genetically encoded fluorescent labelling and vital fluorescent organelle stains. CAT homing and fusion were found to be dependent on adhesion to the surface, in contrast to germ tube development which occurs in the absence of adhesion. Staining with fluorescently labelled concanavalin A indicated that the cell wall composition of CATs differs from that of microconidia and germ tubes. The movement of nuclei, mitochondria, vacuoles and lipid droplets through fused germlings was observed by live-cell imaging.
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Affiliation(s)
- Smija M. Kurian
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester, United Kingdom
| | - Antonio Di Pietro
- Departamento de Genetica, Universidad de Cordoba, Campus Rabanales C5, Cordoba, Spain
| | - Nick D. Read
- Manchester Fungal Infection Group, Institute of Inflammation and Repair, University of Manchester, Manchester, United Kingdom
- * E-mail:
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Abstract
The growth and development of most fungi take place on a two-dimensional surface or within a three-dimensional matrix. The fungal sense of touch is therefore critical for fungi in the interpretation of their environment and often signals the switch to a new developmental state. Contact sensing, or thigmo-based responses, include thigmo differentiation, such as the induction of invasion structures by plant pathogens in response to topography; thigmonasty, where contact with a motile prey rapidly triggers its capture; and thigmotropism, where the direction of hyphal growth is guided by physical features in the environment. Like plants and some bacteria, fungi grow as walled cells. Despite the well-demonstrated importance of thigmo responses in numerous stages of fungal growth and development, it is not known how fungal cells sense contact through the relatively rigid structure of the cell wall. However, while sensing mechanisms at the molecular level are not entirely understood, the downstream signaling pathways that are activated by contact sensing are being elucidated. In the majority of cases, the response to contact is complemented by chemical cues and both are required, either sequentially or simultaneously, to elicit normal developmental responses. The importance of a sense of touch in the lifestyles and development of diverse fungi is highlighted in this review, and the candidate molecular mechanisms that may be involved in fungal contact sensing are discussed.
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Meunier C, Hosseini S, Heidari N, Maryush Z, Johannesson H. Multilevel Selection in the Filamentous Ascomycete Neurospora tetrasperma. Am Nat 2018. [DOI: 10.1086/695803] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Etxebeste O, Espeso EA. Neurons show the path: tip-to-nucleus communication in filamentous fungal development and pathogenesis. FEMS Microbiol Rev 2017; 40:610-24. [PMID: 27587717 DOI: 10.1093/femsre/fuw021] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2016] [Indexed: 01/11/2023] Open
Abstract
Multiple fungal species penetrate substrates and accomplish host invasion through the fast, permanent and unidirectional extension of filamentous cells known as hyphae. Polar growth of hyphae results, however, in a significant increase in the distance between the polarity site, which also receives the earliest information about ambient conditions, and nuclei, where adaptive responses are executed. Recent studies demonstrate that these long distances are overcome by signal transduction pathways which convey sensory information from the polarity site to nuclei, controlling development and pathogenesis. The present review compares the striking connections of the mechanisms for long-distance communication in hyphae with those from neurons, and discusses the importance of their study in order to understand invasion and dissemination processes of filamentous fungi, and design strategies for developmental control in the future.
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Affiliation(s)
- Oier Etxebeste
- Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country (UPV/EHU), 20018 San Sebastian, Spain
| | - Eduardo A Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
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Fu C, Heitman J. PRM1 and KAR5 function in cell-cell fusion and karyogamy to drive distinct bisexual and unisexual cycles in the Cryptococcus pathogenic species complex. PLoS Genet 2017; 13:e1007113. [PMID: 29176784 PMCID: PMC5720818 DOI: 10.1371/journal.pgen.1007113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 12/07/2017] [Accepted: 11/13/2017] [Indexed: 11/18/2022] Open
Abstract
Sexual reproduction is critical for successful evolution of eukaryotic organisms in adaptation to changing environments. In the opportunistic human fungal pathogens, the Cryptococcus pathogenic species complex, C. neoformans primarily undergoes bisexual reproduction, while C. deneoformans undergoes both unisexual and bisexual reproduction. During both unisexual and bisexual cycles, a common set of genetic circuits regulates a yeast-to-hyphal morphological transition, that produces either monokaryotic or dikaryotic hyphae. As such, both the unisexual and bisexual cycles can generate genotypic and phenotypic diversity de novo. Despite the similarities between these two cycles, genetic and morphological differences exist, such as the absence of an opposite mating-type partner and monokaryotic instead of dikaryotic hyphae during C. deneoformans unisexual cycle. To better understand the similarities and differences between these modes of sexual reproduction, we focused on two cellular processes involved in sexual reproduction: cell-cell fusion and karyogamy. We identified orthologs of the plasma membrane fusion protein Prm1 and the nuclear membrane fusion protein Kar5 in both Cryptococcus species, and demonstrated their conserved roles in cell fusion and karyogamy during C. deneoformans α-α unisexual reproduction and C. deneoformans and C. neoformans a-α bisexual reproduction. Notably, karyogamy occurs inside the basidum during bisexual reproduction in C. neoformans, but often occurs earlier following cell fusion during bisexual reproduction in C. deneoformans. Characterization of these two genes also showed that cell fusion is dispensable for solo unisexual reproduction in C. deneoformans. The blastospores produced along hyphae during C. deneoformans unisexual reproduction are diploid, suggesting that diploidization occurs early during hyphal development, possibly through either an endoreplication pathway or cell fusion-independent karyogamy events. Taken together, our findings suggest distinct mating mechanisms for unisexual and bisexual reproduction in Cryptococcus, exemplifying distinct evolutionary trajectories within this pathogenic species complex.
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Affiliation(s)
- Ci Fu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States of America
- * E-mail:
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Three-dimensional visualization and a deep-learning model reveal complex fungal parasite networks in behaviorally manipulated ants. Proc Natl Acad Sci U S A 2017; 114:12590-12595. [PMID: 29114054 PMCID: PMC5703306 DOI: 10.1073/pnas.1711673114] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Some microbes possess the ability to adaptively manipulate host behavior. To better understand how such microbial parasites control animal behavior, we examine the cell-level interactions between the species-specific fungal parasite Ophiocordyceps unilateralis sensu lato and its carpenter ant host (Camponotus castaneus) at a crucial moment in the parasite's lifecycle: when the manipulated host fixes itself permanently to a substrate by its mandibles. The fungus is known to secrete tissue-specific metabolites and cause changes in host gene expression as well as atrophy in the mandible muscles of its ant host, but it is unknown how the fungus coordinates these effects to manipulate its host's behavior. In this study, we combine techniques in serial block-face scanning-electron microscopy and deep-learning-based image segmentation algorithms to visualize the distribution, abundance, and interactions of this fungus inside the body of its manipulated host. Fungal cells were found throughout the host body but not in the brain, implying that behavioral control of the animal body by this microbe occurs peripherally. Additionally, fungal cells invaded host muscle fibers and joined together to form networks that encircled the muscles. These networks may represent a collective foraging behavior of this parasite, which may in turn facilitate host manipulation.
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Abstract
ABSTRACT
For the majority of fungal species, the somatic body of an individual is a network of interconnected cells sharing a common cytoplasm and organelles. This syncytial organization contributes to an efficient distribution of resources, energy, and biochemical signals. Cell fusion is a fundamental process for fungal development, colony establishment, and habitat exploitation and can occur between hyphal cells of an individual colony or between colonies of genetically distinct individuals. One outcome of cell fusion is the establishment of a stable heterokaryon, culminating in benefits for each individual via shared resources or being of critical importance for the sexual or parasexual cycle of many fungal species. However, a second outcome of cell fusion between genetically distinct strains is formation of unstable heterokaryons and the induction of a programmed cell death reaction in the heterokaryotic cells. This reaction of nonself rejection, which is termed heterokaryon (or vegetative) incompatibility, is widespread in the fungal kingdom and acts as a defense mechanism against genome exploitation and mycoparasitism. Here, we review the currently identified molecular players involved in the process of somatic cell fusion and its regulation in filamentous fungi. Thereafter, we summarize the knowledge of the molecular determinants and mechanism of heterokaryon incompatibility and place this phenomenon in the broader context of biotropic interactions and immunity.
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Purin S, Morton JB. Anastomosis behavior differs between asymbiotic and symbiotic hyphae ofRhizophagus clarus. Mycologia 2017; 105:589-602. [PMID: 23233505 DOI: 10.3852/12-135] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Sonia Purin
- Universidade Federal de Santa Catarina, Rod. Ulysses Gaboardi km 3, Curitibanos, SC 89.520-000, Brazil
| | - Joseph B. Morton
- West Virginia University, 1090 Agricultural Sciences Building, Morgantown, West Virginia 26506
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Fleißner A, Herzog S. Signal exchange and integration during self-fusion in filamentous fungi. Semin Cell Dev Biol 2016; 57:76-83. [DOI: 10.1016/j.semcdb.2016.03.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/06/2016] [Accepted: 03/22/2016] [Indexed: 11/16/2022]
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Shahi S, Fokkens L, Houterman PM, Rep M. Suppressor of fusion, a Fusarium oxysporum homolog of Ndt80, is required for nutrient-dependent regulation of anastomosis. Fungal Genet Biol 2016; 95:49-57. [PMID: 27531696 DOI: 10.1016/j.fgb.2016.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 08/10/2016] [Accepted: 08/12/2016] [Indexed: 11/25/2022]
Abstract
Heterokaryon formation is an essential step in asexual recombination in Fusarium oxysporum. Filamentous fungi have an elaborate nonself recognition machinery to prevent formation and proliferation of heterokaryotic cells, called heterokaryon incompatibility (HI). In F. oxysporum the regulation of this machinery is not well understood. In Neurospora crassa, Vib-1, a putative transcription factor of the p53-like Ndt80 family of transcription factors, has been identified as global regulator of HI. In this study we investigated the role of the F. oxysporum homolog of Vib-1, called Suf, in vegetative hyphal and conidial anastomosis tube (CAT) fusion and HI. We identified a novel function for an Ndt80 homolog as a nutrient-dependent regulator of anastomosis. Strains carrying the SUF deletion mutation display a hyper-fusion phenotype during vegetative growth as well as germling development. In addition, conidial paring of incompatible SUF deletion strains led to more heterokaryon formation, which is independent of suppression of HI. Our data provides further proof for the divergence in the functions of different members Ndt80 family. We propose that Ndt80 homologs mediate responses to nutrient quality and quantity, with specific responses varying between species.
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Affiliation(s)
- Shermineh Shahi
- Molecular Plant Pathology, University of Amsterdam, Amsterdam, The Netherlands
| | - Like Fokkens
- Molecular Plant Pathology, University of Amsterdam, Amsterdam, The Netherlands
| | - Petra M Houterman
- Molecular Plant Pathology, University of Amsterdam, Amsterdam, The Netherlands
| | - Martijn Rep
- Molecular Plant Pathology, University of Amsterdam, Amsterdam, The Netherlands.
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40
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Genre A, Lanfranco L. Endophytic coming out: the expressorium as a novel fungal structure specialized in outward-directed penetration of the leaf cuticle. THE NEW PHYTOLOGIST 2016; 211:5-7. [PMID: 27240707 DOI: 10.1111/nph.14002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 04/08/2016] [Indexed: 06/05/2023]
Affiliation(s)
- Andrea Genre
- Department of Life Science and Systems Biology, University of Torino, Viale P. A. Mattioli 25, Torino, 10125, Italy
| | - Luisa Lanfranco
- Department of Life Science and Systems Biology, University of Torino, Viale P. A. Mattioli 25, Torino, 10125, Italy
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Heller J, Zhao J, Rosenfield G, Kowbel DJ, Gladieux P, Glass NL. Characterization of Greenbeard Genes Involved in Long-Distance Kind Discrimination in a Microbial Eukaryote. PLoS Biol 2016; 14:e1002431. [PMID: 27077707 PMCID: PMC4831770 DOI: 10.1371/journal.pbio.1002431] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/11/2016] [Indexed: 01/09/2023] Open
Abstract
Microorganisms are capable of communication and cooperation to perform social activities. Cooperation can be enforced using kind discrimination mechanisms in which individuals preferentially help or punish others, depending on genetic relatedness only at certain loci. In the filamentous fungus Neurospora crassa, genetically identical asexual spores (germlings) communicate and fuse in a highly regulated process, which is associated with fitness benefits during colony establishment. Recognition and chemotropic interactions between isogenic germlings requires oscillation of the mitogen-activated protein kinase (MAPK) signal transduction protein complex (NRC-1, MEK-2, MAK-2, and the scaffold protein HAM-5) to specialized cell fusion structures termed conidial anastomosis tubes. Using a population of 110 wild N. crassa isolates, we investigated germling fusion between genetically unrelated individuals and discovered that chemotropic interactions are regulated by kind discrimination. Distinct communication groups were identified, in which germlings within one communication group interacted at high frequency, while germlings from different communication groups avoided each other. Bulk segregant analysis followed by whole genome resequencing identified three linked genes (doc-1, doc-2, and doc-3), which were associated with communication group phenotype. Alleles at doc-1, doc-2, and doc-3 fell into five haplotypes that showed transspecies polymorphism. Swapping doc-1 and doc-2 alleles from different communication group strains was necessary and sufficient to confer communication group affiliation. During chemotropic interactions, DOC-1 oscillated with MAK-2 to the tips of conidial anastomosis tubes, while DOC-2 was statically localized to the plasma membrane. Our data indicate that doc-1, doc-2, and doc-3 function as "greenbeard" genes, involved in mediating long-distance kind recognition that involves actively searching for one's own type, resulting in cooperation between non-genealogical relatives. Our findings serve as a basis for investigations into the mechanisms associated with attraction, fusion, and kind recognition in other eukaryotic species.
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Affiliation(s)
- Jens Heller
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | - Jiuhai Zhao
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | - Gabriel Rosenfield
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | - David J. Kowbel
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
| | | | - N. Louise Glass
- The Plant and Microbial Biology Department, The University of California, Berkeley, California, United States of America
- * E-mail:
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42
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Nuclear dynamics and genetic rearrangement in heterokaryotic colonies of Fusarium oxysporum. Fungal Genet Biol 2016; 91:20-31. [PMID: 27013267 DOI: 10.1016/j.fgb.2016.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/31/2016] [Accepted: 03/15/2016] [Indexed: 10/22/2022]
Abstract
Recent studies have shown horizontal transfer of chromosomes to be a potential key contributor to genome plasticity in asexual fungal pathogens. However, the mechanisms behind horizontal chromosome transfer in eukaryotes are not well understood. Here we investigated the role of conidial anastomosis in heterokaryon formation between incompatible strains of Fusarium oxysporum and determined the importance of heterokaryons for horizontal chromosome transfer. Using live-cell imaging we demonstrate that conidial pairing of incompatible strains under carbon starvation can result in the formation of viable heterokaryotic hyphae in F. oxysporum. Nuclei of the parental lines presumably fuse at some stage as conidia with a single nucleus harboring both marker histones (GFP- and RFP-tagged) are produced. Upon colony formation, this hybrid offspring is subject to progressive and gradual genome rearrangement. The parental genomes appear to become spatially separated and RFP-tagged histones, deriving from one of the strains, Fol4287, are eventually lost. With a PCR-based method we showed that markers for most of the chromosomes of this strain are lost, indicating a lack of Fol4287 chromosomes. This leaves offspring with the genomic background of the other strain (Fo47), but in some cases together with one or two chromosomes from Fol4287, including the chromosome that confers pathogenicity towards tomato.
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Cheeseman K, Ropars J, Renault P, Dupont J, Gouzy J, Branca A, Abraham AL, Ceppi M, Conseiller E, Debuchy R, Malagnac F, Goarin A, Silar P, Lacoste S, Sallet E, Bensimon A, Giraud T, Brygoo Y. Multiple recent horizontal transfers of a large genomic region in cheese making fungi. Nat Commun 2015; 5:2876. [PMID: 24407037 PMCID: PMC3896755 DOI: 10.1038/ncomms3876] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 11/06/2013] [Indexed: 02/01/2023] Open
Abstract
While the extent and impact of horizontal transfers in prokaryotes are widely acknowledged, their importance to the eukaryotic kingdom is unclear and thought by many to be anecdotal. Here we report multiple recent transfers of a huge genomic island between Penicillium spp. found in the food environment. Sequencing of the two leading filamentous fungi used in cheese making, P. roqueforti and P. camemberti, and comparison with the penicillin producer P. rubens reveals a 575 kb long genomic island in P. roqueforti—called Wallaby—present as identical fragments at non-homologous loci in P. camemberti and P. rubens. Wallaby is detected in Penicillium collections exclusively in strains from food environments. Wallaby encompasses about 250 predicted genes, some of which are probably involved in competition with microorganisms. The occurrence of multiple recent eukaryotic transfers in the food environment provides strong evidence for the importance of this understudied and probably underestimated phenomenon in eukaryotes. Horizontal gene transfers are known to play an important role in prokaryote evolution but their impact and prevalence in eukaryotes is less clear. Here, the authors sequence the genomes of cheese making fungi P. roqueforti and P. camemberti, and provide evidence for recent horizontal transfers of a large genomic region.
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Affiliation(s)
- Kevin Cheeseman
- INRA, UMR1319 Micalis, F-78352 Jouy-en-Josas, France; Genomic Vision, 80-84 rue des Meuniers, 92220 Bagneux, France; AgroParisTech, UMR Micalis, F-78352 Jouy-en-Josas, France
| | - Jeanne Ropars
- Origine, Structure, Evolution de la Biodiversité, UMR 7205 CNRS-MNHN, Muséum National d'Histoire Naturelle, CP39, 57 rue Cuvier, 75231 Paris Cedex 05, France; Univ Paris-Sud, Ecologie, Systématique et Evolution, UMR8079, 91405 Orsay, France; CNRS, Ecologie, Systématique et Evolution, UMR8079, 91405 Orsay, France
| | - Pierre Renault
- INRA, UMR1319 Micalis, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR Micalis, F-78352 Jouy-en-Josas, France
| | - Joëlle Dupont
- Origine, Structure, Evolution de la Biodiversité, UMR 7205 CNRS-MNHN, Muséum National d'Histoire Naturelle, CP39, 57 rue Cuvier, 75231 Paris Cedex 05, France
| | - Jérôme Gouzy
- LIMP Toulouse, INRA/CNRS, INRA, 24 Chemin de Borde Rouge-Auzeville, CS 52627, 31326 Castanet-Tolosan Cedex, France; INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, F-31326 Castanet-Tolosan, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, F-31326 Castanet-Tolosan, France
| | - Antoine Branca
- Univ Paris-Sud, Ecologie, Systématique et Evolution, UMR8079, 91405 Orsay, France; CNRS, Ecologie, Systématique et Evolution, UMR8079, 91405 Orsay, France
| | - Anne-Laure Abraham
- INRA, UMR1319 Micalis, F-78352 Jouy-en-Josas, France; AgroParisTech, UMR Micalis, F-78352 Jouy-en-Josas, France
| | - Maurizio Ceppi
- Genomic Vision, 80-84 rue des Meuniers, 92220 Bagneux, France
| | | | - Robert Debuchy
- Univ Paris-Sud, Institut de Génétique et Microbiologie, UMR8621, 91405 Orsay, France; CNRS, Institut de Génétique et Microbiologie UMR8621, 91405 Orsay, France
| | - Fabienne Malagnac
- Univ Paris-Sud, Institut de Génétique et Microbiologie, UMR8621, 91405 Orsay, France; Univ Paris Diderot, Sorbonne Paris Cité, Institut des Energies de Demain (IED), 75205 Paris, France
| | - Anne Goarin
- Univ Paris-Sud, Institut de Génétique et Microbiologie, UMR8621, 91405 Orsay, France
| | - Philippe Silar
- Univ Paris-Sud, Institut de Génétique et Microbiologie, UMR8621, 91405 Orsay, France; Univ Paris Diderot, Sorbonne Paris Cité, Institut des Energies de Demain (IED), 75205 Paris, France
| | - Sandrine Lacoste
- Origine, Structure, Evolution de la Biodiversité, UMR 7205 CNRS-MNHN, Muséum National d'Histoire Naturelle, CP39, 57 rue Cuvier, 75231 Paris Cedex 05, France
| | - Erika Sallet
- LIMP Toulouse, INRA/CNRS, INRA, 24 Chemin de Borde Rouge-Auzeville, CS 52627, 31326 Castanet-Tolosan Cedex, France; INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, F-31326 Castanet-Tolosan, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, F-31326 Castanet-Tolosan, France
| | - Aaron Bensimon
- Genomic Vision, 80-84 rue des Meuniers, 92220 Bagneux, France
| | - Tatiana Giraud
- Univ Paris-Sud, Ecologie, Systématique et Evolution, UMR8079, 91405 Orsay, France; CNRS, Ecologie, Systématique et Evolution, UMR8079, 91405 Orsay, France
| | - Yves Brygoo
- 13 ruelle d'Aigrefoin 78470 St Rémy-lès-Chevreuse
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The AngFus3 Mitogen-Activated Protein Kinase Controls Hyphal Differentiation and Secondary Metabolism in Aspergillus niger. EUKARYOTIC CELL 2015; 14:602-15. [PMID: 25888553 DOI: 10.1128/ec.00018-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 04/13/2015] [Indexed: 01/04/2023]
Abstract
Adaptation to a changing environment is essential for the survival and propagation of sessile organisms, such as plants or fungi. Filamentous fungi commonly respond to a worsening of their growth conditions by differentiation of asexually or sexually produced spores. The formation of these specialized cell types is, however, also triggered as part of the general life cycle by hyphal age or density. Spores typically serve for dispersal and, therefore, translocation but can also act as resting states to endure times of scarcity. Eukaryotic differentiation in response to environmental and self-derived signals is commonly mediated by three-tiered mitogen-activated protein (MAP) kinase signaling cascades. Here, we report that the MAP kinase Fus3 of the black mold Aspergillus niger (AngFus3) and its upstream kinase AngSte7 control vegetative spore formation and secondary metabolism. Mutants lacking these kinases are defective in conidium induction in response to hyphal density but are fully competent in starvation-induced sporulation, indicating that conidiation in A. niger is triggered by various independent signals. In addition, the mutants exhibit an altered profile of volatile metabolites and secrete dark pigments into the growth medium, suggesting a dysregulation of the secondary metabolism. By assigning the AngFus3 MAP kinase pathway to the transduction of a potentially self-derived trigger, this work contributes to the unraveling of the intricate signaling networks controlling fungal differentiation. Moreover, our data further support earlier observations that differentiation and secondary metabolism are tightly linked in filamentous fungi.
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Shoji JY, Charlton ND, Yi M, Young CA, Craven KD. Vegetative hyphal fusion and subsequent nuclear behavior in Epichloë grass endophytes. PLoS One 2015; 10:e0121875. [PMID: 25837972 PMCID: PMC4383479 DOI: 10.1371/journal.pone.0121875] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 02/18/2015] [Indexed: 01/18/2023] Open
Abstract
Epichloë species (including the former genus Neotyphodium) are fungal symbionts of many agronomically important forage grasses, and provide their grass hosts with protection from a wide range of biotic and abiotic stresses. Epichloë species include many interspecific hybrids with allodiploid-like genomes, which may provide the potential for combined traits or recombination to generate new traits. Though circumstantial evidence suggests that such interspecific hybrids might have arisen from nuclear fusion events following vegetative hyphal fusion between different Epichloë strains, this hypothesis has not been addressed empirically. Here, we investigated vegetative hyphal fusion and subsequent nuclear behavior in Epichloë species. A majority of Epichloë strains, especially those having a sexual stage, underwent self vegetative hyphal fusion. Vegetative fusion also occurred between two hyphae from different Epichloë strains. Though Epichloë spp. are uninucleate fungi, hyphal fusion resulted in two nuclei stably sharing the same cytoplasm, which might ultimately lead to nuclear fusion. In addition, protoplast fusion experiments gave rise to uninucleate putative hybrids, which apparently had two markers, one from each parent within the same nucleus. These results are consistent with the notion that interspecific hybrids arise from vegetative hyphal fusion. However, we also discuss additional factors, such as post-hybridization selection, that may be important to explain the recognized prevalence of hybrids in Epichloë species.
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Affiliation(s)
- Jun-ya Shoji
- The Samuel Roberts Noble Foundation, Plant Biology Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Nikki D. Charlton
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Mihwa Yi
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Carolyn A. Young
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Kelly D. Craven
- The Samuel Roberts Noble Foundation, Plant Biology Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
- * E-mail:
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Thynne E, McDonald MC, Solomon PS. Phytopathogen emergence in the genomics era. TRENDS IN PLANT SCIENCE 2015; 20:246-255. [PMID: 25682011 DOI: 10.1016/j.tplants.2015.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 01/13/2015] [Accepted: 01/19/2015] [Indexed: 06/04/2023]
Abstract
Phytopathogens are a global threat to plant agriculture and biodiversity. The genomics era has lead to an exponential rise in comparative gene and genome studies of both economically significant and insignificant microorganisms. In this review we highlight some recent comparisons and discuss how they identify shared genes or genomic regions associated with host virulence. The two major mechanisms of rapid genome adaptation - horizontal gene transfer and hybridisation - are reviewed and we consider how intra-specific pan-genome sequences encode alternative host specificity. We also discuss the power that access to expansive gene databases provides in aiding the study of phytopathogen emergence. These databases can rapidly enable the identification of an unknown pathogen and its origin, as well as genomic adaptations required for emergence.
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Affiliation(s)
- Elisha Thynne
- Plant Sciences Division, Research School of Biology, The Australian National University, Canberra, 2601, ACT, Australia
| | - Megan C McDonald
- Plant Sciences Division, Research School of Biology, The Australian National University, Canberra, 2601, ACT, Australia
| | - Peter S Solomon
- Plant Sciences Division, Research School of Biology, The Australian National University, Canberra, 2601, ACT, Australia.
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Bastiaans E, Debets AJM, Aanen DK. Experimental demonstration of the benefits of somatic fusion and the consequences for allorecognition. Evolution 2015; 69:1091-9. [PMID: 25688421 DOI: 10.1111/evo.12626] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 02/03/2015] [Indexed: 12/31/2022]
Abstract
Allorecognition, the ability to distinguish "self" from "nonself" based on allelic differences at allorecognition loci, is common in all domains of life. Allorecognition restricts the opportunities for social parasitism, and is therefore crucial for the evolution of cooperation. However, the maintenance of allorecognition diversity provides a paradox. If allorecognition is costly relative to cooperation, common alleles will be favored. Thus, the cost of allorecognition may reduce the genetic variation upon which allorecognition crucially relies, a prediction now known as "Crozier's paradox." We establish the relative costs of allorecognition, and their consequences for the short-term evolution of recognition labels theoretically predicted by Crozier. We use fusion among colonies of the fungus Neurospora crassa, regulated by highly variable allorecognition genes, as an experimental model system. We demonstrate that fusion among colonies is mutually beneficial, relative to absence of fusion upon allorecognition. This benefit is due not only to absence of mutual antagonism, which occurs upon allorecognition, but also to an increase in colony size per se. We then experimentally demonstrate that the benefit of fusion selects against allorecognition diversity, as predicted by Crozier. We discuss what maintains allorecognition diversity.
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Affiliation(s)
- Eric Bastiaans
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg 1, 6708 PD, Wageningen, The Netherlands.
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Becker Y, Eaton CJ, Brasell E, May KJ, Becker M, Hassing B, Cartwright GM, Reinhold L, Scott B. The Fungal Cell-Wall Integrity MAPK Cascade Is Crucial for Hyphal Network Formation and Maintenance of Restrictive Growth of Epichloë festucae in Symbiosis With Lolium perenne. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:69-85. [PMID: 25303335 DOI: 10.1094/mpmi-06-14-0183-r] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Epichloë festucae is a mutualistic symbiont that systemically colonizes the intercellular spaces of Lolium perenne leaves to form a highly structured and interconnected hyphal network. In an Agrobacterium tumefaciens T-DNA forward genetic screen, we identified a mutant TM1066 that had a severe host interaction phenotype, causing stunting and premature senescence of the host. Molecular analysis revealed that the mutation responsible for this phenotype was in the cell-wall integrity (CWI) mitogen-activated protein kinase kinase (MAPKK), mkkA. Mutants generated by targeted deletion of the mkkA or the downstream mpkA kinase recapitulated the phenotypes observed for TM1066. Both mutants were defective in hyphal cell–cell fusion, formed intrahyphal hyphae, had enhanced conidiation, and showed microcyclic conidiation. Transmission electron microscopy and confocal microscopy analysis of leaf tissue showed that mutant hyphae were more abundant than the wild type in the intercellular spaces and colonized the vascular bundles. Hyphal branches failed to fuse but, instead, grew past one another to form bundles of convoluted hyphae. Mutant hyphae showed increased fluorescence with AF488-WGA, indicative of increased accessibility of chitin, a hypothesis supported by changes in the cell-wall ultrastructure. These results show that the CWI MAPK pathway is a key signaling pathway for controlling the mutualistic symbiotic interaction between E. festucae and L. perenne.
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