1
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Van Nuland ME, Daws SC, Bailey JK, Schweitzer JA, Busby PE, Peay KG. Above- and belowground fungal biodiversity of Populus trees on a continental scale. Nat Microbiol 2023; 8:2406-2419. [PMID: 37973868 DOI: 10.1038/s41564-023-01514-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 10/04/2023] [Indexed: 11/19/2023]
Abstract
Understanding drivers of terrestrial fungal communities over large scales is an important challenge for predicting the fate of ecosystems under climate change and providing critical ecological context for bioengineering plant-microbe interactions in model systems. We conducted an extensive molecular and microscopy field study across the contiguous United States measuring natural variation in the Populus fungal microbiome among tree species, plant niche compartments and key symbionts. Our results show clear biodiversity hotspots and regional endemism of Populus-associated fungal communities explained by a combination of climate, soil and geographic factors. Modelling climate change impacts showed a deterioration of Populus mycorrhizal associations and an increase in potentially pathogenic foliar endophyte diversity and prevalence. Geographic differences among these symbiont groups in their sensitivity to environmental change are likely to influence broader forest health and ecosystem function. This dataset provides an above- and belowground atlas of Populus fungal biodiversity at a continental scale.
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Affiliation(s)
- Michael E Van Nuland
- Department of Biology, Stanford University, Stanford, CA, USA.
- Society for the Protection of Underground Networks, SPUN, Dover, DE, USA.
| | - S Caroline Daws
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Joseph K Bailey
- Ecology and Evolutionary Biology Department, University of Tennessee, Knoxville, TN, USA
| | - Jennifer A Schweitzer
- Ecology and Evolutionary Biology Department, University of Tennessee, Knoxville, TN, USA
| | - Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Kabir G Peay
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Earth System Science, Stanford University, Stanford, CA, USA
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2
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Newcombe G, Marlin M, Barge E, Heitmann S, Ridout M, Busby PE. Plant Seeds Commonly Host Bacillus spp., Potential Antagonists of Phytopathogens. Microb Ecol 2023; 85:1356-1366. [PMID: 35552795 DOI: 10.1007/s00248-022-02024-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 04/25/2022] [Indexed: 05/10/2023]
Abstract
In agriculture, horticulture and plantation forestry, Bacillus species are the most commonly applied antagonists and biopesticides, targeting plant pathogens and insect pests, respectively. Bacillus isolates are also used as bacterial plant biostimulants, or BPBs. Such useful isolates of Bacillus are typically sourced from soil. Here, we show that Bacillus - and other antagonistic microbes - can be sourced from a broad range of plant seeds. We found that culturable Bacillus isolates are common in the seeds of 98 plant species representing 39 families (i.e., 87% of the commonly cultured bacteria belonged to Bacillales). We also found that 83% of the commonly cultured fungi from the seeds of the 98 plant species belonged to just three orders of fungi-Pleosporales, Hypocreales and Eurotiales-that are also associated with antagonism. Furthermore, we confirmed antagonism potential in agaro with seed isolates of Bacillus from Pinus monticola as a representative case. Eight isolates each of seed Bacillus, seed fungi, and foliar fungi, all from P. monticola, were paired in a total of 384 possible pair-wise interactions (with seed and foliar fungi as the targets). Seed Bacillus spp. were the strongest antagonists of the seed and foliar fungi, with a mean interaction strength 2.8 times greater than seed fungi (all either Eurotiales or Hypocreales) and 3.2 times greater than needle fungi. Overall, our study demonstrates that seeds host a taxonomically narrow group of culturable, antagonistic bacteria and fungi.
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Affiliation(s)
- George Newcombe
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, 83844-1133, USA
| | - Maria Marlin
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, 83844-1133, USA
| | - Edward Barge
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Sabrina Heitmann
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Mary Ridout
- University of Idaho Extension Washington County, College of Agriculture and Life Sciences, Weiser, ID, 83672, USA
| | - Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA.
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3
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Still CJ, Sibley A, DePinte D, Busby PE, Harrington CA, Schulze M, Shaw DR, Woodruff D, Rupp DE, Daly C, Hammond WM, Page GFM. Causes of widespread foliar damage from the June 2021 Pacific Northwest Heat Dome: more heat than drought. Tree Physiol 2023; 43:203-209. [PMID: 36611006 DOI: 10.1093/treephys/tpac143] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 12/11/2022] [Indexed: 06/17/2023]
Affiliation(s)
- C J Still
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA
| | - A Sibley
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA
| | - D DePinte
- US Department of Agriculture, Forest Service, Pacific Northwest Region, State & Private Forestry, Forest Health Protection, Redmond, OR 97756, USA
| | - P E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - C A Harrington
- US Department of Agriculture, Forest Service, Pacific Northwest Research Station, Olympia, WA 98512, USA
| | - M Schulze
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA
| | - D R Shaw
- Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, OR 97331, USA
| | - D Woodruff
- US Department of Agriculture, Forest Service, Pacific Northwest Research Station, Corvallis, OR 97331, USA
| | - D E Rupp
- Oregon Climate Change Research Institute, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - C Daly
- PRISM Climate Group, Northwest Alliance for Computational Science and Engineering, Oregon State University, Corvallis, OR 97331, USA
| | - W M Hammond
- Agronomy Department, University of Florida, Institute of Food and Agricultural Sciences, Gainesville, FL 32611, USA
| | - G F M Page
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Locked Bag 104, Bentley Delivery Centre, Bentley, Western Australia 6983, Australia
- CSIRO Land and Water, Private Bag 5, Wembley, Western Australia 6913, Australia
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4
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Meyer KM, Deines P, Wei Z, Busby PE, Lindow SE, Bohannan BJM. Editorial: The role of dispersal and transmission in structuring microbial communities. Front Microbiol 2022; 13:1054498. [PMID: 36338039 PMCID: PMC9627547 DOI: 10.3389/fmicb.2022.1054498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 10/06/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Kyle M. Meyer
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States
- *Correspondence: Kyle M. Meyer
| | - Peter Deines
- Zoological Institute, Christian Albrechts University Kiel, Kiel, Germany
| | - Zhong Wei
- College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing, China
| | - Posy E. Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, United States
| | - Steven E. Lindow
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
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5
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Abstract
Tree planting and natural regeneration contribute to the ongoing effort to restore Earth's forests. Our review addresses how the plant microbiome can enhance the survival of planted and naturally regenerating seedlings and serve in long-term forest carbon capture and the conservation of biodiversity. We focus on fungal leaf endophytes, ubiquitous defensive symbionts that protect against pathogens. We first show that fungal and oomycetous pathogen richness varies greatly for tree species native to the United States (n = 0-876 known pathogens per US tree species), with nearly half of tree species either without pathogens in these major groups or with unknown pathogens. Endophytes are insurance against the poorly known and changing threat of tree pathogens. Next, we review studies of plant phyllosphere feedback, but knowledge gaps prevent us from evaluating whether adding conspecific leaf litter to planted seedlings promotes defensive symbiosis, analogous to adding soil to promote positive feedback. Finally, we discuss research priorities for integrating the plant microbiome into efforts to expand Earth's forests.
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Affiliation(s)
- Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA;
| | - George Newcombe
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, Idaho, USA
| | - Abigail S Neat
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA;
| | - Colin Averill
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
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6
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Barge EG, Leopold DR, Rojas A, Vilgalys R, Busby PE. Phylogenetic conservatism of mycoparasitism and its contribution to pathogen antagonism. Mol Ecol 2022; 31:3018-3030. [DOI: 10.1111/mec.16436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 03/06/2022] [Accepted: 03/16/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Edward G. Barge
- Department of Botany and Plant Pathology Oregon State University Corvallis OR 97331 USA
| | - Devin R. Leopold
- Department of Botany and Plant Pathology Oregon State University Corvallis OR 97331 USA
| | - Alejandro Rojas
- Department of Entomology and Plant Pathology University of Arkansas Fayetteville AR 72701 USA
| | - Rytas Vilgalys
- Department of Biology Duke University Durham NC 27708 USA
| | - Posy E. Busby
- Department of Botany and Plant Pathology Oregon State University Corvallis OR 97331 USA
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7
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Abstract
Fungal symbionts occur in all plant tissues, and many aid their host plants with critical functions, including nutrient acquisition, defense against pathogens, and tolerance of abiotic stress. "Core" taxa in the plant mycobiome, defined as fungi present across individuals, populations, or time, may be particularly crucial to plant survival during the challenging seedling stage. However, studies on core seed fungi are limited to individual sampling sites, raising the question of whether core taxa exist across large geographic scales. We addressed this question using both culture-based and culture-free techniques to identify the fungi found in individual seeds collected from nine provenances across the range of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii), a foundation tree species in the Pacific Northwest and a globally important timber crop that is propagated commercially by seed. Two key findings emerged: (i) Seed mycobiome composition differed among seed provenances. (ii) Despite variation in the seed mycobiome, we detected four core members, none of which is a known pathogen of Douglas-fir: Trichoderma spp., Hormonema macrosporum, Mucor plumbeus, and Talaromyces rugulosus. Our results support the concept of a core seed microbiome, yet additional work is needed to determine the functional consequences of core taxa for seedling germination, growth, survival, and competition.
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Affiliation(s)
- Gillian E Bergmann
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331.,Bio-Protection Research Centre, Lincoln University, Lincoln, Canterbury, New Zealand
| | - Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
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8
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Christian N, Espino Basurto B, Toussaint A, Xu X, Ainsworth EA, Busby PE, Heath KD. Elevated carbon dioxide reduces a common soybean leaf endophyte. Glob Chang Biol 2021; 27:4154-4168. [PMID: 34022078 DOI: 10.1111/gcb.15716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
Free-air CO2 enrichment (FACE) experiments have elucidated how climate change affects plant physiology and production. However, we lack a predictive understanding of how climate change alters interactions between plants and endophytes, critical microbial mediators of plant physiology and ecology. We leveraged the SoyFACE facility to examine how elevated [CO2 ] affected soybean (Glycine max) leaf endophyte communities in the field. Endophyte community composition changed under elevated [CO2 ], including a decrease in the abundance of a common endophyte, Methylobacterium sp. Moreover, Methylobacterium abundance was negatively correlated with co-occurring fungal endophytes. We then assessed how Methylobacterium affected the growth of co-occurring endophytic fungi in vitro. Methylobacterium antagonized most co-occurring fungal endophytes in vitro, particularly when it was more established in culture before fungal introduction. Variation in fungal response to Methylobacterium within a single fungal operational taxonomic unit (OTU) was comparable to inter-OTU variation. Finally, fungi isolated from elevated vs. ambient [CO2 ] plots differed in colony growth and response to Methylobacterium, suggesting that increasing [CO2 ] may affect fungal traits and interactions within the microbiome. By combining in situ and in vitro studies, we show that elevated [CO2 ] decreases the abundance of a common bacterial endophyte that interacts strongly with co-occurring fungal endophytes. We suggest that endophyte responses to global climate change will have important but largely unexplored implications for both agricultural and natural systems.
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Affiliation(s)
- Natalie Christian
- Department of Biology, University of Louisville, Louisville, KY, USA
- Department of Plant Biology, School of Integrative Biology, University of Illinois, Urbana, IL, USA
| | - Baldemar Espino Basurto
- Department of Plant Biology, School of Integrative Biology, University of Illinois, Urbana, IL, USA
| | - Amber Toussaint
- Department of Plant Biology, School of Integrative Biology, University of Illinois, Urbana, IL, USA
| | - Xinyan Xu
- Department of Plant Biology, School of Integrative Biology, University of Illinois, Urbana, IL, USA
| | - Elizabeth A Ainsworth
- Department of Plant Biology, School of Integrative Biology, University of Illinois, Urbana, IL, USA
- USDA ARS Global Change and Photosynthesis Research Unit, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
| | - Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Katy D Heath
- Department of Plant Biology, School of Integrative Biology, University of Illinois, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA
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9
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Newcombe G, Fraser SJ, Ridout M, Busby PE. Leaf Endophytes of Populus trichocarpa Act as Pathogens of Neighboring Plant Species. Front Microbiol 2020; 11:573056. [PMID: 33281769 PMCID: PMC7705171 DOI: 10.3389/fmicb.2020.573056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/15/2020] [Indexed: 11/22/2022] Open
Abstract
The conventional definition of endophytes is that they do not cause disease, whereas pathogens do. Complicating this convention, however, is the poorly explored phenomenon that some microbes are endophytes in some plants but pathogens in others. Black cottonwood or poplar (Populus trichocarpa) and wheat (Triticum aestivum) are common wild and crop plants, respectively, in the Pacific Northwest USA. The former anchors wild, riparian communities, whereas the latter is an introduced domesticate of commercial importance in the region. We isolated Fusarium culmorum – a well-known pathogen of wheat causing both blight and rot – from the leaf of a black cottonwood tree in western Washington. The pathogenicity of this cottonwood isolate and of a wheat isolate of F. culmorum were compared by inoculating both cottonwood and wheat in a greenhouse experiment. We found that both the cottonwood and wheat isolates of F. culmorum significantly reduced the growth of wheat, whereas they had no impact on cottonwood growth. Our results demonstrate that the cottonwood isolate of F. culmorum is endophytic in one plant species but pathogenic in another. Using sequence-based methods, we found an additional 56 taxa in the foliar microbiome of cottonwood that matched the sequences of pathogens of other plants of the region. These sequence-based findings suggest, though they do not prove, that P. trichocarpa may host many additional pathogens of other plants.
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Affiliation(s)
- George Newcombe
- Department of Forest, Rangeland, and Fire Sciences, College of Natural Resources, University of Idaho, Moscow, ID, United States
| | - Shannon J Fraser
- Department of Forest, Rangeland, and Fire Sciences, College of Natural Resources, University of Idaho, Moscow, ID, United States
| | - Mary Ridout
- College of Agriculture and Life Sciences, University of Idaho Extension Washington County, Weiser, ID, United States
| | - Posy E Busby
- Department of Botany and Plant Pathology, College of Agricultural Sciences, Oregon State University, Corvallis, OR, United States
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10
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Wagner MR, Busby PE, Balint-Kurti P. Analysis of leaf microbiome composition of near-isogenic maize lines differing in broad-spectrum disease resistance. New Phytol 2020; 225:2152-2165. [PMID: 31657460 DOI: 10.1111/nph.16284] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 10/18/2019] [Indexed: 06/10/2023]
Abstract
Plant genotype strongly affects disease resistance, and also influences the composition of the leaf microbiome. However, these processes have not been studied and linked in the microevolutionary context of breeding for improved disease resistance. We hypothesised that broad-spectrum disease resistance alleles also affect colonisation by nonpathogenic symbionts. Quantitative trait loci (QTL) conferring resistance to multiple fungal pathogens were introgressed into a disease-susceptible maize inbred line. Bacterial and fungal leaf microbiomes of the resulting near-isogenic lines were compared with the microbiome of the disease-susceptible parent line at two time points in multiple fields. Introgression of QTL from disease-resistant lines strongly shifted the relative abundance of diverse fungal and bacterial taxa in both 3-wk-old and 7-wk-old plants. Nevertheless, the effects on overall community structure and diversity were minor and varied among fields and years. Contrary to our expectations, host genotype effects were not any stronger in fields with high disease pressure than in uninfected fields, and microbiome succession over time was similar in heavily infected and uninfected plants. These results show that introgressed QTL can greatly improve broad-spectrum disease resistance while having only limited and inconsistent pleiotropic effects on the leaf microbiome in maize.
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Affiliation(s)
- Maggie R Wagner
- Department of Ecology and Evolutionary Biology, Kansas Biological Survey, University of Kansas, Lawrence, KS, 66047, USA
| | - Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Peter Balint-Kurti
- Plant Science Research Unit, Agricultural Research Service, United States Department of Agriculture, Raleigh, NC, 27695, USA
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27695, USA
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11
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Zanne AE, Abarenkov K, Afkhami ME, Aguilar-Trigueros CA, Bates S, Bhatnagar JM, Busby PE, Christian N, Cornwell WK, Crowther TW, Flores-Moreno H, Floudas D, Gazis R, Hibbett D, Kennedy P, Lindner DL, Maynard DS, Milo AM, Nilsson RH, Powell J, Schildhauer M, Schilling J, Treseder KK. Fungal functional ecology: bringing a trait-based approach to plant-associated fungi. Biol Rev Camb Philos Soc 2019; 95:409-433. [PMID: 31763752 DOI: 10.1111/brv.12570] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 10/27/2019] [Accepted: 10/31/2019] [Indexed: 12/21/2022]
Abstract
Fungi play many essential roles in ecosystems. They facilitate plant access to nutrients and water, serve as decay agents that cycle carbon and nutrients through the soil, water and atmosphere, and are major regulators of macro-organismal populations. Although technological advances are improving the detection and identification of fungi, there still exist key gaps in our ecological knowledge of this kingdom, especially related to function. Trait-based approaches have been instrumental in strengthening our understanding of plant functional ecology and, as such, provide excellent models for deepening our understanding of fungal functional ecology in ways that complement insights gained from traditional and -omics-based techniques. In this review, we synthesize current knowledge of fungal functional ecology, taxonomy and systematics and introduce a novel database of fungal functional traits (FunFun ). FunFun is built to interface with other databases to explore and predict how fungal functional diversity varies by taxonomy, guild, and other evolutionary or ecological grouping variables. To highlight how a quantitative trait-based approach can provide new insights, we describe multiple targeted examples and end by suggesting next steps in the rapidly growing field of fungal functional ecology.
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Affiliation(s)
- Amy E Zanne
- Department of Biological Sciences, George Washington University, Washington, DC, 20052, U.S.A
| | - Kessy Abarenkov
- Natural History Museum, University of Tartu, Vanemuise 46, Tartu, 51014, Estonia
| | - Michelle E Afkhami
- Department of Biology, University of Miami, Coral Gables, FL, 33146, U.S.A
| | - Carlos A Aguilar-Trigueros
- Freie Universität-Berlin, Berlin-Brandenburg Institute of Advanced Biodiversity Research, 14195, Berlin, Germany
| | - Scott Bates
- Department of Biological Sciences, Purdue University Northwest, Westville, IN, 46391, U.S.A
| | | | - Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97330, U.S.A
| | - Natalie Christian
- Department of Plant Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, U.S.A.,Department of Biology, University of Louisville, Louisville, KY 40208, U.S.A
| | - William K Cornwell
- Evolution & Ecology Research Centre, School of Biological Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, 2052, Australia
| | - Thomas W Crowther
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland
| | - Habacuc Flores-Moreno
- Department of Ecology, Evolution, and Behavior, and Department of Forest Resources, University of Minnesota, St. Paul, MN, 55108, U.S.A
| | - Dimitrios Floudas
- Microbial Ecology Group, Department of Biology, Lund University, Lund, Sweden
| | - Romina Gazis
- Department of Plant Pathology, Tropical Research & Education Center, University of Florida, Homestead, FL, 33031, U.S.A
| | - David Hibbett
- Biology Department, Clark University, Worcester, MA, 01610, U.S.A
| | - Peter Kennedy
- Plant & Microbial Biology, University of Minnesota, St. Paul, MN, 55108, U.S.A
| | - Daniel L Lindner
- US Forest Service, Northern Research Station, Center for Forest Mycology Research, Madison, Wisconsin, WI, 53726, U.S.A
| | - Daniel S Maynard
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland
| | - Amy M Milo
- Department of Biological Sciences, George Washington University, Washington, DC, 20052, U.S.A
| | - Rolf Henrik Nilsson
- University of Gothenburg, Department of Biological and Environmental Sciences, Gothenburg Global Biodiversity Centre, Box 461, 405 30, Göteborg, Sweden
| | - Jeff Powell
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia
| | - Mark Schildhauer
- National Center for Ecological Analysis and Synthesis, 735 State Street, Suite 300, Santa Barbara, CA, 93101, U.S.A
| | - Jonathan Schilling
- Plant & Microbial Biology, University of Minnesota, St. Paul, MN, 55108, U.S.A
| | - Kathleen K Treseder
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, 92697, U.S.A
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12
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Busby PE, Crutsinger G, Barbour M, Newcombe G. Contingency rules for pathogen competition and antagonism in a genetically based, plant defense hierarchy. Ecol Evol 2019; 9:6860-6868. [PMID: 31380021 PMCID: PMC6662256 DOI: 10.1002/ece3.5253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 03/29/2019] [Accepted: 04/06/2019] [Indexed: 01/19/2023] Open
Abstract
Plant defense against pathogens includes a range of mechanisms, including, but not limited to, genetic resistance, pathogen-antagonizing endophytes, and pathogen competitors. The relative importance of each mechanism can be expressed in a hierarchical view of defense. Several recent studies have shown that pathogen antagonism is inconsistently expressed within the plant defense hierarchy. Our hypothesis is that the hierarchy is governed by contingency rules that determine when and where antagonists reduce plant disease severity.Here, we investigated whether pathogen competition influences pathogen antagonism using Populus as a model system. In three independent field experiments, we asked whether competition for leaf mesophyll cells between a Melampsora rust pathogen and a microscopic, eriophyid mite affects rust pathogen antagonism by fungal leaf endophytes. The rust pathogen has an annual, phenological disadvantage in competition with the mite because the rust pathogen must infect its secondary host in spring before infecting Populus. We varied mite-rust competition by utilizing Populus genotypes characterized by differential genetic resistance to the two organisms. We inoculated plants with endophytes and allowed mites and rust to infect plants naturally.Two contingency rules emerged from the three field experiments: (a) Pathogen antagonism by endophytes can be preempted by host genes for resistance that suppress pathogen development, and (b) pathogen antagonism by endophytes can secondarily be preempted by competitive exclusion of the rust by the mite. Synthesis: Our results point to a Populus defense hierarchy with resistance genes on top, followed by pathogen competition, and finally pathogen antagonism by endophytes. We expect these rules will help to explain the variation in pathogen antagonism that is currently attributed to context dependency.
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Affiliation(s)
- Posy E. Busby
- Botany and Plant Pathology DepartmentOregon State UniversityCorvallisOregon
| | - Gregory Crutsinger
- Department of ZoologyUniversity of British ColumbiaVancouverBritish Columbia
| | - Matthew Barbour
- Department of ZoologyUniversity of British ColumbiaVancouverBritish Columbia
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13
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Abstract
Schizoempodium mesophyllincola is an eriophyid mite that feeds in leaves of Populus trichocarpa in the central part of this cottonwood tree’s range (i.e., coastal British Columbia, Washington and Oregon) in the Pacific Northwest (PNW) of North America, and on some interspecific hybrids planted in short-rotation, intensive forestry in the region. The mite, a leaf vagrant, sucks the contents of spongy mesophyll cells, causing leaf discoloration, or “bronzing.” Here, we investigate the inheritance pattern of resistance to leaf bronzing using a three-generation Populus trichocarpa x P. deltoides hybrid pedigree. We found that resistance to the mite is an exaptation in that its source in two related F2 families of the TxD hybrid pedigree was the non-native host, P. deltoides. Two grandparental genotypes of the latter, ‘ILL-5’ and ‘ILL-129’, were completely free of the bronzing symptom and that phenotype was inherited in a Mendelian manner in the F1 and F2. Resistance to S. mesophyllincola is similar to resistance to many other regional pathogens of P. trichocarpa (e.g., Melampsora occidentalis, Venturia inopina, Sphaerulina populicola, and Taphrina sp.) in that it is inherited from the non-native grandparent (e.g., P. deltoides, P. nigra, or P. maximowiczii) in three-generation, hybrid pedigrees. In addition to finding evidence for Mendelian inheritance, we found two QTLs with LOD scores 5.03 and 3.12 mapped on linkage groups (LG) III and I, and they explained 6.7 and 4.2% of the phenotypic variance, respectively. The LG I QTL is close to, or synonymous with, one for resistance to sap-feeding arthropods and leaf developmental traits as expressed in a British study utilizing the same pedigree.
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Affiliation(s)
- George Newcombe
- College of Natural Resources, University of Idaho, Moscow, Idaho, United States of America
- * E-mail:
| | - Wellington Muchero
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - Posy E. Busby
- Botany and Plant Pathology Department, Cordley Hall, Oregon State University, Corvallis, Oregon, United States of America
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14
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Abstract
The plant microbiome may be bottlenecked at the level of endophytes of individual seeds. Strong defense of developing seeds is predicted by optimal defense theory, and we have experimentally demonstrated exclusionary interactions among endophytic microbes infecting individual seeds of Centaurea stoebe. Having found a single, PDA-culturable microbe per seed or none in an exploratory study with Centaurea stoebe, we completed a more extensive survey of an additional 98 plant species representing 39 families. We again found that individual, surface-sterilized seeds of all species hosted only one PDA-culturable bacterial or fungal endophyte per seed, or none. PDA-unculturables were not determined but we expect them to also be bottlenecked in individual seeds, as they too should be governed by exclusionary interactions. If the bottleneck were confirmed with high-throughput sequencing of individual seeds then it would make sense to further investigate the Primary Symbiont Hypothesis (PSH). This includes the prediction that primary symbionts (i.e., the winners of the exclusionary battles among seed endophytes) have strong effects on seedlings depending on symbiont identity.
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Affiliation(s)
- George Newcombe
- Department of Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID, United States
| | - Abby Harding
- Department of Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID, United States
| | - Mary Ridout
- Department of Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID, United States
| | - Posy E. Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, United States
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15
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Abstract
High-throughput sequencing of taxon-specific loci, or DNA metabarcoding, has become an invaluable tool for investigating the composition of plant-associated fungal communities and for elucidating plant-fungal interactions. While sequencing fungal communities has become routine, there remain numerous potential sources of systematic error that can introduce biases and compromise metabarcoding data. This chapter presents a protocol for DNA metabarcoding of the leaf mycobiome based on current best practices to minimize errors through careful laboratory practices and validation.
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Affiliation(s)
- Shawn P Brown
- Department of Biological Sciences, University of Memphis, Memphis, TN, USA
| | - Devin R Leopold
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Posy E Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.
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16
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Busby PE, Soman C, Wagner MR, Friesen ML, Kremer J, Bennett A, Morsy M, Eisen JA, Leach JE, Dangl JL. Research priorities for harnessing plant microbiomes in sustainable agriculture. PLoS Biol 2017; 15:e2001793. [PMID: 28350798 PMCID: PMC5370116 DOI: 10.1371/journal.pbio.2001793] [Citation(s) in RCA: 336] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Feeding a growing world population amidst climate change requires optimizing the reliability, resource use, and environmental impacts of food production. One way to assist in achieving these goals is to integrate beneficial plant microbiomes-i.e., those enhancing plant growth, nutrient use efficiency, abiotic stress tolerance, and disease resistance-into agricultural production. This integration will require a large-scale effort among academic researchers, industry researchers, and farmers to understand and manage plant-microbiome interactions in the context of modern agricultural systems. Here, we identify priorities for research in this area: (1) develop model host-microbiome systems for crop plants and non-crop plants with associated microbial culture collections and reference genomes, (2) define core microbiomes and metagenomes in these model systems, (3) elucidate the rules of synthetic, functionally programmable microbiome assembly, (4) determine functional mechanisms of plant-microbiome interactions, and (5) characterize and refine plant genotype-by-environment-by-microbiome-by-management interactions. Meeting these goals should accelerate our ability to design and implement effective agricultural microbiome manipulations and management strategies, which, in turn, will pay dividends for both the consumers and producers of the world food supply.
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Affiliation(s)
- Posy E. Busby
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Chinmay Soman
- Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana Champaign, Urbana, Illinois, United States of America
| | - Maggie R. Wagner
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Maren L. Friesen
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, United States of America
- Program in Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, Michigan, United States of America
| | - James Kremer
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, United States of America
| | - Alison Bennett
- The James Hutton Institute, Invergowrie, Dundee, Scotland
| | - Mustafa Morsy
- College of Natural Sciences and Mathematics, University of West Alabama, Livingston, Alabama, United States of America
| | - Jonathan A. Eisen
- Genome Center, University of California, Davis, California, United States of America
| | - Jan E. Leach
- Bioagricultural Sciences and Pest Management, Colorado State University, Ft Collins, Colorado, United States of America
| | - Jeffery L. Dangl
- Howard Hughes Medical Institute, Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
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17
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Abstract
Many recent studies have demonstrated that non-pathogenic fungi within plant microbiomes, i.e., endophytes ("endo" = within, "phyte" = plant), can significantly modify the expression of host plant disease. The rapid pace of advancement in endophyte ecology warrants a pause to synthesize our understanding of endophyte disease modification and to discuss future research directions. We reviewed recent literature on fungal endophyte disease modification, and here report on several emergent themes: (1) Fungal endophyte effects on plant disease span the full spectrum from pathogen antagonism to pathogen facilitation, with pathogen antagonism most commonly reported. (2) Agricultural plant pathosystems are the focus of research on endophyte disease modification. (3) A taxonomically diverse group of fungal endophytes can influence plant disease severity. And (4) Fungal endophyte effects on plant disease severity are context-dependent. Our review highlights the importance of fungal endophytes for plant disease across a broad range of plant pathosystems, yet simultaneously reveals that complexity within plant microbiomes presents a significant challenge to disentangling the biotic environmental factors affecting plant disease severity. Manipulative studies integrating eco-evolutionary approaches with emerging molecular tools will be poised to elucidate the functional importance of endophytes in natural plant pathosystems that are fundamental to biodiversity and conservation.
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Affiliation(s)
- Posy E Busby
- Department of Biology, Duke University, Durham, NC, 287708, USA.
- Department of Forest, Rangelands and Fire Sciences, University of Idaho, Moscow, ID, 83844-1133, USA.
| | - Mary Ridout
- Department of Forest, Rangelands and Fire Sciences, University of Idaho, Moscow, ID, 83844-1133, USA
| | - George Newcombe
- Department of Forest, Rangelands and Fire Sciences, University of Idaho, Moscow, ID, 83844-1133, USA
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18
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Busby PE, Peay KG, Newcombe G. Common foliar fungi of Populus trichocarpa modify Melampsora rust disease severity. New Phytol 2016; 209:1681-92. [PMID: 26565565 DOI: 10.1111/nph.13742] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 10/01/2015] [Indexed: 05/23/2023]
Abstract
Nonpathogenic foliar fungi (i.e. endophytes and epiphytes) can modify plant disease severity in controlled experiments. However, experiments have not been combined with ecological studies in wild plant pathosystems to determine whether disease-modifying fungi are common enough to be ecologically important. We used culture-based methods and DNA sequencing to characterize the abundance and distribution of foliar fungi of Populus trichocarpa in wild populations across its native range (Pacific Northwest, USA). We conducted complementary, manipulative experiments to test how foliar fungi commonly isolated from those populations influence the severity of Melampsora leaf rust disease. Finally, we examined correlative relationships between the abundance of disease-modifying foliar fungi and disease severity in wild trees. A taxonomically and geographically diverse group of common foliar fungi significantly modified disease severity in experiments, either increasing or decreasing disease severity. Spatial patterns in the abundance of some of these foliar fungi were significantly correlated (in predicted directions) with disease severity in wild trees. Our study reveals that disease modification is an ecological function shared by common foliar fungal symbionts of P. trichocarpa. This finding raises new questions about plant disease ecology and plant biodiversity, and has applied potential for disease management.
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Affiliation(s)
- Posy E Busby
- Department of Biology, Duke University, Durham, NC, 27708, USA
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, 83843-1133, USA
| | - Kabir G Peay
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - George Newcombe
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, 83843-1133, USA
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Busby PE, Lamit LJ, Keith AR, Newcombe G, Gehring CA, Whitham TG, Dirzo R. Genetics-based interactions among plants, pathogens, and herbivores define arthropod community structure. Ecology 2015; 96:1974-84. [PMID: 26378319 DOI: 10.1890/13-2031.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Plant resistance to pathogens or insect herbivores is common, but its potential for indirectly influencing plant-associated communities is poorly known. Here, we test whether pathogens' indirect effects on arthropod communities and herbivory depend on plant resistance to pathogens and/or herbivores, and address the overarching interacting foundation species hypothesis that genetics-based interactions among a few highly interactive species can structure a much larger community. In a manipulative field experiment using replicated genotypes of two Populus species and their interspecific hybrids, we found that genetic variation in plant resistance to both pathogens and insect herbivores modulated the strength of pathogens' indirect effects on arthropod communities and insect herbivory. First, due in part to the pathogens' differential impacts on leaf biomass among the two Populus species and the hybrids, the pathogen most strongly impacted arthropod community composition, richness, and abundance on the pathogen-susceptible tree species. Second, we found similar patterns comparing pathogen-susceptible and pathogen-resistant genotypes within species. Third, within a plant species, pathogens caused a fivefold greater reduction in herbivory on insect-herbivore-susceptible plant genotypes than on herbivore-resistant genotypes, demonstrating that the pathogen-herbivore interaction is genotype dependent. We conclude that interactions among plants, pathogens, and herbivores can structure multitrophic communities, supporting the interacting foundation species hypothesis. Because these interactions are genetically based, evolutionary changes in genetic resistance could result in ecological changes in associated communities, which may in turn feed back to affect plant fitness.
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20
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Houbraken J, Visagie CM, Meijer M, Frisvad JC, Busby PE, Pitt JI, Seifert KA, Louis-Seize G, Demirel R, Yilmaz N, Jacobs K, Christensen M, Samson RA. A taxonomic and phylogenetic revision of Penicillium section Aspergilloides. Stud Mycol 2014; 78:373-451. [PMID: 25492984 PMCID: PMC4255628 DOI: 10.1016/j.simyco.2014.09.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Species belonging to Penicillium section Aspergilloides have a world-wide distribution with P. glabrum, P. spinulosum and P. thomii the most well-known species of this section. These species occur commonly and can be isolated from many substrates including soil, food, bark and indoor environments. The taxonomy of these species has been investigated several times using various techniques, but species delimitation remains difficult. In the present study, 349 strains belonging to section Aspergilloides were subjected to multilocus molecular phylogenetic analyses using partial β-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) sequences. Section Aspergilloides is subdivided into 12 clades and 51 species. Twenty-five species are described here as new and P. yezoense, a species originally described without a Latin diagnosis, is validated. Species belonging to section Aspergilloides are phenotypically similar and most have monoverticillate conidiophores and grow moderately or quickly on agar media. The most important characters to distinguish these species were colony sizes on agar media, growth at 30 °C, ornamentation and shape of conidia, sclerotium production and stipe roughness.
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Affiliation(s)
- J Houbraken
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, NL-3584 CT Utrecht, The Netherlands
| | - C M Visagie
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, NL-3584 CT Utrecht, The Netherlands
| | - M Meijer
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, NL-3584 CT Utrecht, The Netherlands
| | - J C Frisvad
- Department of Systems Biology, Building 221, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - P E Busby
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA
| | - J I Pitt
- CSIRO Animal, Food and Health Sciences, North Ryde, NSW 2113, Australia
| | - K A Seifert
- Biodiversity (Mycology), Agriculture & Agri-Food Canada, Ottawa, ON K1A 0C6, Canada
| | - G Louis-Seize
- Biodiversity (Mycology), Agriculture & Agri-Food Canada, Ottawa, ON K1A 0C6, Canada
| | - R Demirel
- Department of Biology, Faculty of Science, Anadolu University, Turkey
| | - N Yilmaz
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, NL-3584 CT Utrecht, The Netherlands
| | - K Jacobs
- Department of Microbiology, University of Stellenbosch, Private Bag X1, Stellenbosch 7600, South Africa
| | - M Christensen
- Botany Department, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA
| | - R A Samson
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, NL-3584 CT Utrecht, The Netherlands
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Busby PE, Zimmerman N, Weston DJ, Jawdy SS, Houbraken J, Newcombe G. Leaf endophytes andPopulusgenotype affect severity of damage from the necrotrophic leaf pathogen,Drepanopeziza populi. Ecosphere 2013. [DOI: 10.1890/es13-00127.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Busby PE, Catherine Aime M, Newcombe G. Foliar pathogens of Populus angustifolia are consistent with a hypothesis of Beringian migration into North America. Fungal Biol 2012; 116:792-801. [DOI: 10.1016/j.funbio.2012.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 04/19/2012] [Accepted: 04/24/2012] [Indexed: 11/15/2022]
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Pringle EG, Adams RI, Broadbent E, Busby PE, Donatti CI, Kurten EL, Renton K, Dirzo R. Distinct Leaf-trait Syndromes of Evergreen and Deciduous Trees in a Seasonally Dry Tropical Forest. Biotropica 2010. [DOI: 10.1111/j.1744-7429.2010.00697.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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