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Oostlander AG, Brodde L, von Bargen M, Leiterholt M, Trautmann D, Enderle R, Elfstrand M, Stenlid J, Fleißner A. A Reliable and Simple Method for the Production of Viable Pycnidiospores of the Pine Pathogen Diplodia sapinea and a Spore-Based Infection Assay on Scots Pine. PLANT DISEASE 2023; 107:3370-3377. [PMID: 37163310 DOI: 10.1094/pdis-01-23-0107-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: 05/11/2023]
Abstract
Diplodia sapinea is a globally distributed opportunistic fungal pathogen of conifers that causes severe production losses in forestry. The fungus frequently colonizes pine trees as an endophyte without causing visible symptoms but can become pathogenic when the host plant is weakened by stress, such as drought or heat. Forest damage might therefore further increase due to the effects of climate change. The future development of control strategies depends on a better understanding of the fungus' biology, which requires experimental methods for its investigation in the laboratory. An efficient, standardized protocol for the production and storage of highly viable pycnidiospores was developed, and a spore-based infection method was devised. We compared infection rates of dormant and actively growing, wounded, or nonwounded Scots pine seedlings inoculated with in vitro-produced spores and mycelium from agar-plugs. Spores were a much more efficient inoculum for causing disease symptoms on wounded plants than the conventional agar plug. The application of spores on nonwounded plants lead to high rates of asymptomatic infection, suggesting endophytic fungal development. These methods enable standardized spore infection and virulence assays and promote D. sapinea as a model organism for studying the switch from endophytic to pathogenic life styles of forest pathogens.
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Affiliation(s)
- Anne G Oostlander
- Institute of Genetics, Technical University Braunschweig, Braunschweig, Germany
| | - Laura Brodde
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Miriam von Bargen
- Institute of Genetics, Technical University Braunschweig, Braunschweig, Germany
| | - Marco Leiterholt
- Institute of Genetics, Technical University Braunschweig, Braunschweig, Germany
| | - Dagmar Trautmann
- Institute of Forest Protection, Julius Kuehn Institute (JKI), Braunschweig, Germany
- Institute for Plant Protection in Horticulture and Urban Green, Julius Kuehn Institute (JKI), Braunschweig, Germany
| | - Rasmus Enderle
- Institute of Forest Protection, Julius Kuehn Institute (JKI), Braunschweig, Germany
- Institute for Plant Protection in Horticulture and Urban Green, Julius Kuehn Institute (JKI), Braunschweig, Germany
| | - Malin Elfstrand
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jan Stenlid
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - André Fleißner
- Institute of Genetics, Technical University Braunschweig, Braunschweig, Germany
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Fungi associated with woody tissues of Acer pseudoplatanus in forest stands with different health status concerning sooty bark disease (Cryptostroma corticale). Mycol Prog 2023. [DOI: 10.1007/s11557-022-01861-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
AbstractFrom 2018 to 2020, Germany experienced periods of exceptional weather conditions. Extremely high summer temperatures and precipitation deficits induced stress and mortality in forest trees. Acer pseudoplatanus (sycamore) was one of the affected tree species. Symptoms of sooty bark disease (SBD) and severe damage of entire stands, both caused by the fungal species Cryptostroma corticale, were reported more frequently. To explore the non-symptomatic distribution of C. corticale, wood cores from visibly healthy sycamore stems were sampled and all outgrowing fungi were identified and recorded. In total, 50 trees, aged 30–65 years, were sampled at five different forest stands, from which 91 endophytic filamentous morphotypes could be isolated. The fungal endophytic community in the woody tissue of the sycamore trees varied greatly at the different sites and between the trees. The number of isolated morphotypes at the different sites ranged from 13 to 44 and no morphotype was found at all sites. At 1.20-m stem height, 3.3 fungi could be isolated from woody tissue per tree on average. The most abundant species isolated from visibly healthy sycamore in regard to both occurrence at the studied sites and continuity was C. corticale. It was recorded at four of the studied forest stands, from 26% of all studied sycamore trees, and had a frequency of 7.85% relative to the 293 isolated filamentous strains that were isolated. The second most abundant species was Xylaria longipes followed by Lopadostoma turgidum. In this study clear evidence for the endophytic lifestyle of C. corticale is presented which thus appears to be spread further than expected based on visible SBD symptoms.
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Ortiz B, Enríquez L, Mejía K, Yanez Y, Sorto Y, Guzman S, Aguilar K, Fontecha G. Molecular characterization of endophytic fungi from pine (Pinus oocarpa) in Honduras. BIONATURA 2022. [DOI: 10.21931/rb/2022.07.03.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Pine is one of the important coniferous genera in America. In Honduras, Pinus oocarpa is the most critical conifer species since it plays an essential role for the country's economy and represents a symbol of national identity. Endophytic fungi are defined as microorganisms that reside in the internal tissues of plants without causing any obvious immediate negative effects and are an integral part of their associated microbial communities. This study aimed to isolate and characterize the endophytic fungi present in the pines of Honduras through the amplification and sequencing of the ribosomal RNA gene's internal transcribed spacer (ITS). A total of 7 pines from the department of El Paraíso in eastern Honduras were analyzed. A total of 14 fungi grouped into 6 genera and 7 species were isolated: Fusarium lateritium, F. pseudocircinatum, Pestalotiopsis pini, P. microspora, Xylaria grammica, Trichoderma atroviride, y Nigrospora oryzae. To our knowledge, this is the first report of endophytic fungal species in pines in Honduras. Although some endophytic fungi may be mutualistic or saprophytic, the present study shows the presence of several genera of endophytic fungi that have been reported as pine pathogens. The presence of these fungi in the pines of Honduras represents a potential threat to the health of the forest. Further research is needed to increase knowledge about the importance of these fungi and the potential impact they could have on pine forests in Honduras.
Keywords: Endophytic fungi, Pinus oocarpa, Honduras
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Affiliation(s)
- Bryan Ortiz
- Microbiology Research Institute; Universidad Nacional Autónoma de Honduras; J1 building. Ciudad Universitaria, Tegucigalpa 11101, Honduras
| | - Lourdes Enríquez
- Microbiology Research Institute; Universidad Nacional Autónoma de Honduras; J1 building. Ciudad Universitaria, Tegucigalpa 11101, Honduras
| | - Karla Mejía
- Instituto Nacional de Conservación y Desarrollo Forestal, Áreas Protegidas y Vida Silvestre (ICF), Colonia Brisas de Olancho, Comayagüela, Honduras
| | - Yensi Yanez
- Instituto Nacional de Conservación y Desarrollo Forestal, Áreas Protegidas y Vida Silvestre (ICF), Colonia Brisas de Olancho, Comayagüela, Honduras
| | - Yuliana Sorto
- Escuela Agrícola Panamericana (EAP). Departamento de Ciencia y Producción Agropecuaria, Laboratorio de control biológico, San Antonio de Oriente, Francisco Morazán, Honduras
| | - Sayda Guzman
- Escuela Agrícola Panamericana (EAP). Departamento de Ciencia y Producción Agropecuaria, Laboratorio de control biológico, San Antonio de Oriente, Francisco Morazán, Honduras
| | - Kateryn Aguilar
- Microbiology Research Institute; Universidad Nacional Autónoma de Honduras; J1 building. Ciudad Universitaria, Tegucigalpa 11101, Honduras
| | - Gustavo Fontecha
- Microbiology Research Institute; Universidad Nacional Autónoma de Honduras; J1 building. Ciudad Universitaria, Tegucigalpa 11101, Honduras
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Blumenstein K, Bußkamp J, Langer GJ, Terhonen E. Diplodia tip blight pathogen's virulence empowered through host switch. FRONTIERS IN FUNGAL BIOLOGY 2022; 3:939007. [PMID: 37746207 PMCID: PMC10512300 DOI: 10.3389/ffunb.2022.939007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 07/04/2022] [Indexed: 09/26/2023]
Abstract
Increased drought combined with emerging pathogens poses an increased threat to forest health. This is attributable to the unpredictable behaviour of forest pathosystems, which can favour fungal pathogens over the host under persistent drought stress conditions. Diplodia sapinea (≡ Sphaeropsis sapinea) is one of the most severe pathogens in Scots pine (Pinus sylvestris) causing Diplodia tip blight (conifer blight) under certain environmental conditions. Recently, the fungus has also been isolated from non-conifer hosts, indicating that it has a broader host range than previously known. In this study we compared the impact of different levels of water availability on necrosis length caused by D. sapinea strains isolated as endophytes (eight strains isolated from asymptomatic Scots pine) and pathogens (five strains isolated from symptomatic Scots pine) and five strains isolated from symptomatic non-pine hosts. For all strains the decreased water availability increased the necrosis length in Scots pine shoots. The isolates from non-pine hosts caused the most severe reactions under all water availabilities. The results of the study indicate the likelihood that effects of climatic changes such as drought will drive D. sapinea damage in Scots pine-dominated forests and increase mortality rates in affected trees. Further, the higher necrosis in the Scots pines caused by strains that had performed a host switch are concerning with regard to future scenarios thus increasing infection pressure on Scots pine from unknown sources.
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Affiliation(s)
- Kathrin Blumenstein
- Forest Pathology Research Group, Department of Forest Botany and Tree Physiology, Faculty of Forest Sciences and Forest Ecology, Georg-August-University Göttingen, Göttingen, Germany
- Chair of Pathology of Trees, Institute of Forestry, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg, Germany
| | - Johanna Bußkamp
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute, Göttingen, Germany
| | - Gitta Jutta Langer
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute, Göttingen, Germany
| | - Eeva Terhonen
- Forest Pathology Research Group, Department of Forest Botany and Tree Physiology, Faculty of Forest Sciences and Forest Ecology, Georg-August-University Göttingen, Göttingen, Germany
- Natural Resources Institute Finland (Luke), Forest Health and Biodiversity, Helsinki, Finland
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Gnilke A, Sanders TGM. Distinguishing Abrupt and Gradual Forest Disturbances With MODIS-Based Phenological Anomaly Series. FRONTIERS IN PLANT SCIENCE 2022; 13:863116. [PMID: 35677238 PMCID: PMC9168887 DOI: 10.3389/fpls.2022.863116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/07/2022] [Indexed: 06/15/2023]
Abstract
Capturing forest disturbances over time is increasingly important to determine the ecosystem's capacity to recover as well as aiding a timely response of foresters. With changes due to climate change increasing the frequencies, a better understanding of forest disturbances and their role in historical development is needed to, on the one hand, develop forest management approaches promoting ecosystem resilience and, on the other hand, provide quick and spatially explicit information to foresters. A large, publicly available satellite imagery spanning more than two decades for large areas of the Earth's surface at varying spatial and temporal resolutions represents a vast, free data source for this. The challenge is 2-fold: (1) obtaining reliable information on forest condition and development from satellite data requires not only quantification of forest loss but rather a differentiated assessment of the extent and severity of forest degradation; (2) standardized and efficient processing routines both are needed to bridge the gap between remote-sensing signals and conventional forest condition parameters to enable forest managers for the operational use of the data. Here, we investigated abiotic and biotic disturbances based on a set of ground validated occurrences in various forest areas across Germany to build disturbance response chronologies and examine event-specific patterns. The proposed workflow is based on the R-package "npphen" for non-parametric vegetation phenology reconstruction and anomaly detection using MODIS EVI time series data. Results show the potential to detect distinct disturbance responses in forest ecosystems and reveal event-specific characteristics. Difficulties still exist for the determination of, e.g., scattered wind throw, due to its subpixel resolution, especially in highly fragmented landscapes and small forest patches. However, the demonstrated method shows potential for operational use as a semi-automatic system to augment terrestrial monitoring in the forestry sector. Combining the more robust EVI and the assessment of the phenological series at a pixel-by-pixel level allows for a changing species cover without false classification as forest loss.
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Affiliation(s)
- Anne Gnilke
- Department of Forest Ecology and Biodiversity, Thünen Institute of Forest Ecosystems, Eberswalde, Germany
- Department of Disturbance Ecology and Vegetation Dynamics, University of Bayreuth, Bayreuth, Germany
| | - Tanja G. M. Sanders
- Department of Forest Ecology and Biodiversity, Thünen Institute of Forest Ecosystems, Eberswalde, Germany
- Department of Disturbance Ecology and Vegetation Dynamics, University of Bayreuth, Bayreuth, Germany
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Healy RA, Arnold AE, Bonito G, Huang YL, Lemmond B, Pfister DH, Smith ME. Endophytism and endolichenism in Pezizomycetes: the exception or the rule? THE NEW PHYTOLOGIST 2022; 233:1974-1983. [PMID: 34839525 DOI: 10.1111/nph.17886] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/07/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Rosanne A Healy
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | - A Elizabeth Arnold
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Gregory Bonito
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | - Yu-Ling Huang
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
- Department of Biology, National Museum of Natural Science, Taichung, 404, Taiwan
| | - Benjamin Lemmond
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | - Donald H Pfister
- Department of Organismic and Evolutionary Biology, Farlow Herbarium, Harvard University, 22 Divinity Ave, Cambridge, MA, 02138-2020, USA
| | - Matthew E Smith
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
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Langer GJ, Bußkamp J. Fungi Associated With Woody Tissues of European Beech and Their Impact on Tree Health. Front Microbiol 2021; 12:702467. [PMID: 34512579 PMCID: PMC8427693 DOI: 10.3389/fmicb.2021.702467] [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: 04/29/2021] [Accepted: 08/05/2021] [Indexed: 11/13/2022] Open
Abstract
Filamentous fungi associated with woody tissues of European Beech (Fagus sylvatica) and isolated from diseased trees and healthy trees were examined in relation to their impact on tree health. To this end, classical culture-based isolation methods, in planta inoculations and fungal identification using ITS-barcode and morphological characters were used. Stem endophytes of healthy beech saplings collected in German forests were isolated to determine endophyte communities in woody stem tissues. Pathogenicity tests were performed on living potted beech saplings using twelve selected fungal pathogens and wood inhabiting fungi (Hypocreales, Botryosphaeriales, and Xylariales) originating mainly from European beech with symptoms of the complex disease Vitality loss, or from bark necroses, or known to be common endophytes of beech. The impact of these ascomycetous fungi with respect to tree health was discussed. The potential influences of endophytic fungi of beech and of test conditions are discussed in relation to the success of inoculation. All tested fungal strains except for Neonectria ditissima were able to establish themselves post inoculation in the beech stems and caused necroses when there was sufficient water, but at different severities. Under the experimental conditions, Botryosphaeria corticola was shown to be the most virulent tested latent pathogen against F. sylvatica. In the context of climate change and global warming, the tested Botryosphaeriaceae are able to play a primary role in the disease progress of Vitality loss of Beech. The key role of Neonectria coccinea in causing bark necroses and the loss of vitality in beech was confirmed because the tested strain induced large lesions on the beech saplings.
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Affiliation(s)
- Gitta Jutta Langer
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute (NW-FVA), Göttingen, Germany
| | - Johanna Bußkamp
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute (NW-FVA), Göttingen, Germany
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Adamson K, Laas M, Blumenstein K, Busskamp J, Langer GJ, Klavina D, Kaur A, Maaten T, Mullett MS, Müller MM, Ondrušková E, Padari A, Pilt E, Riit T, Solheim H, Soonvald L, Tedersoo L, Terhonen E, Drenkhan R. Highly Clonal Structure and Abundance of One Haplotype Characterise the Diplodia sapinea Populations in Europe and Western Asia. J Fungi (Basel) 2021; 7:634. [PMID: 34436173 PMCID: PMC8400067 DOI: 10.3390/jof7080634] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 11/22/2022] Open
Abstract
Diplodia sapinea is a cosmopolitan endophyte and opportunistic pathogen having occurred on several conifer species in Europe for at least 200 years. In Europe, disease outbreaks have increased on several Pinus spp. in the last few decades. In this study, the genetic structure of the European and western Asian D. sapinea population were investigated using 13 microsatellite markers. In total, 425 isolates from 15 countries were analysed. A high clonal fraction and low genetic distance between most subpopulations was found. One single haplotype dominates the European population, being represented by 45.3% of all isolates and found in nearly all investigated countries. Three genetically distinct subpopulations were found: Central/North European, Italian and Georgian. The recently detected subpopulations of D. sapinea in northern Europe (Estonia) share several haplotypes with the German subpopulation. The northern European subpopulations (Latvia, Estonia and Finland) show relatively high genetic diversity compared to those in central Europe suggesting either that the fungus has existed in the North in an asymptomatic/endophytic mode for a long time or that it has spread recently by multiple introductions. Considerable genetic diversity was found even among isolates of a single tree as 16 isolates from a single tree resulted in lower clonal fraction index than most subpopulations in Europe, which might reflect cryptic sexual proliferation. According to currently published allelic patterns, D. sapinea most likely originates from North America or from some unsampled population in Asia or central America. In order to enable the detection of endophytic or latent infections of planting stock by D. sapinea, new species-specific PCR primers (DiSapi-F and Diplo-R) were designed. During the search for Diplodia isolates across the world for species specific primer development, we identified D. africana in California, USA, and in the Canary Islands, which are the first records of this species in North America and in Spain.
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Affiliation(s)
- Kalev Adamson
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Marili Laas
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Kathrin Blumenstein
- Forest Pathology Research Group, Department of Forest Botany and Tree Physiology, Faculty of Forest Sciences and Forest Ecology, Georg-August-University, 37073 Göttingen, Germany; (K.B.); (E.T.)
| | - Johanna Busskamp
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute, 37079 Göttingen, Germany; (J.B.); (G.J.L.)
| | - Gitta J. Langer
- Section Mycology and Complex Diseases, Department of Forest Protection, Northwest German Forest Research Institute, 37079 Göttingen, Germany; (J.B.); (G.J.L.)
| | - Darta Klavina
- Latvian State Forest Research Institute Silava, Rigas 111, LV 2169 Salaspils, Latvia;
| | - Anu Kaur
- Tallinn Botanic Garden, Kloostrimetsa Tee 52, 11913 Tallinn, Estonia;
| | - Tiit Maaten
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Martin S. Mullett
- Phytophthora Research Centre, Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 613 00 Brno, Czech Republic;
| | - Michael M. Müller
- Bioeconomy and Environment, Natural Resources Institute Finland (Luke), P.O. Box 2, 00791 Helsinki, Finland;
| | - Emília Ondrušková
- Department of Plant Pathology and Mycology, Institute of Forest Ecology Slovak Academy of Sciences, 949 01 Nitra, Slovakia;
| | - Allar Padari
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
| | - Enn Pilt
- Estonian Environment Agency, Mustamäe Tee 33, 10616 Tallinn, Estonia;
| | - Taavi Riit
- Center of Mycology and Microbiology, Institute of Ecology and Earth Sciences, University of Tartu, 14a Ravila, 50411 Tartu, Estonia; (T.R.); (L.T.)
| | - Halvor Solheim
- Norwegian Institute of Bioeconomy Research, 1431 Ås, Norway;
| | - Liina Soonvald
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia;
| | - Leho Tedersoo
- Center of Mycology and Microbiology, Institute of Ecology and Earth Sciences, University of Tartu, 14a Ravila, 50411 Tartu, Estonia; (T.R.); (L.T.)
| | - Eeva Terhonen
- Forest Pathology Research Group, Department of Forest Botany and Tree Physiology, Faculty of Forest Sciences and Forest Ecology, Georg-August-University, 37073 Göttingen, Germany; (K.B.); (E.T.)
| | - Rein Drenkhan
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, 51014 Tartu, Estonia; (M.L.); (T.M.); (A.P.); (R.D.)
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The Diplodia Tip Blight Pathogen Sphaeropsis sapinea Is the Most Common Fungus in Scots Pines' Mycobiome, Irrespective of Health Status-A Case Study from Germany. J Fungi (Basel) 2021; 7:jof7080607. [PMID: 34436146 PMCID: PMC8396920 DOI: 10.3390/jof7080607] [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: 07/14/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 11/17/2022] Open
Abstract
The opportunistic pathogen Sphaeropsis sapinea (≡Diplodia sapinea) is one of the most severe pathogens in Scots pine, causing the disease Diplodia tip blight on coniferous tree species. Disease symptoms become visible when trees are weakened by stress. Sphaeropsis sapinea has an endophytic mode in its lifecycle, making it difficult to detect before disease outbreaks. This study aims to record how S. sapinea accumulates in trees of different health status and, simultaneously, monitor seasonal and age-related fluctuations in the mycobiome. We compared the mycobiome of healthy and diseased Scots pines. Twigs were sampled in June and September 2018, and filamentous fungi were isolated. The mycobiome was analyzed by high-throughput sequencing (HTS) of the ITS2 region. A PERMANOVA analysis confirmed that the mycobiome community composition significantly differed between growth years (p < 0.001) and sampling time (p < 0.001) but not between healthy and diseased trees. Sphaeropsis sapinea was the most common endophyte isolated and the second most common in the HTS data. The fungus was highly abundant in symptomless (healthy) trees, presenting in its endophytic mode. Our results highlight the ability of S. sapinea to accumulate unnoticed as an endophyte in healthy trees before the disease breaks out, representing a sudden threat to Scots pines in the future, especially with increasing drought conditions experienced by pines.
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Siddique AB, Biella P, Unterseher M, Albrectsen BR. Mycobiomes of Young Beech Trees Are Distinguished by Organ Rather Than by Habitat, and Community Analyses Suggest Competitive Interactions Among Twig Fungi. Front Microbiol 2021; 12:646302. [PMID: 33936005 PMCID: PMC8086555 DOI: 10.3389/fmicb.2021.646302] [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: 12/26/2020] [Accepted: 03/03/2021] [Indexed: 11/13/2022] Open
Abstract
Beech trees (Fagus sylvatica) are prominent keystone species of great economic and environmental value for central Europe, hosting a diverse mycobiome. The composition of endophyte communities may depend on tree health, plant organ or tissue, and growth habitat. To evaluate mycobiome communalities at local scales, buds, and twigs were sampled from two young healthy mountain beech stands in Bavaria, Germany, four kilometers apart. With Illumina high-throughput sequencing, we found 113 fungal taxa from 0.7 million high-quality reads that mainly consisted of Ascomycota (52%) and Basidiomycota (26%) taxa. Significant correlations between richness and diversity indices were observed (p < 0.05), and mycobiomes did not differ between habitats in the current study. Species richness and diversity were higher in twigs compared to spring buds, and the assemblages in twigs shared most similarities. Interaction network analyses revealed that twig-bound fungi shared similar numbers of (interaction) links with others, dominated by negative co-occurrences, suggesting that competitive exclusion may be the predominant ecological interaction in the highly connected twig mycobiome. Combining community and network analyses strengthened the evidence that plant organs may filter endophytic communities directly through colonization access and indirectly by facilitating competitive interactions between the fungi.
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Affiliation(s)
- Abu Bakar Siddique
- Department of Ecology and Environmental Sciences, Faculty of Science and Technology, Umeå University, Umeå, Sweden
| | - Paolo Biella
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
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