1
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Seabloom EW, Caldeira MC, Davies KF, Kinkel L, Knops JMH, Komatsu KJ, MacDougall AS, May G, Millican M, Moore JL, Perez LI, Porath-Krause AJ, Power SA, Prober SM, Risch AC, Stevens C, Borer ET. Globally consistent response of plant microbiome diversity across hosts and continents to soil nutrients and herbivores. Nat Commun 2023; 14:3516. [PMID: 37316485 DOI: 10.1038/s41467-023-39179-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 06/01/2023] [Indexed: 06/16/2023] Open
Abstract
All multicellular organisms host a diverse microbiome composed of microbial pathogens, mutualists, and commensals, and changes in microbiome diversity or composition can alter host fitness and function. Nonetheless, we lack a general understanding of the drivers of microbiome diversity, in part because it is regulated by concurrent processes spanning scales from global to local. Global-scale environmental gradients can determine variation in microbiome diversity among sites, however an individual host's microbiome also may reflect its local micro-environment. We fill this knowledge gap by experimentally manipulating two potential mediators of plant microbiome diversity (soil nutrient supply and herbivore density) at 23 grassland sites spanning global-scale gradients in soil nutrients, climate, and plant biomass. Here we show that leaf-scale microbiome diversity in unmanipulated plots depended on the total microbiome diversity at each site, which was highest at sites with high soil nutrients and plant biomass. We also found that experimentally adding soil nutrients and excluding herbivores produced concordant results across sites, increasing microbiome diversity by increasing plant biomass, which created a shaded microclimate. This demonstration of consistent responses of microbiome diversity across a wide range of host species and environmental conditions suggests the possibility of a general, predictive understanding of microbiome diversity.
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Affiliation(s)
- Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, 55108, USA.
| | - Maria C Caldeira
- Forest Research Centre, Associate Laboratory TERRA, School of Agriculture, University of Lisbon, Lisbon, Portugal
| | - Kendi F Davies
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80305, USA
| | - Linda Kinkel
- Department of Plant Pathology, University of Minnesota, St. Paul, MN, 55108, USA
| | - Johannes M H Knops
- Health and Environmental Sciences Department, Xi'an Jiaotong-Liverpool University, Suzhou, China
| | | | | | - Georgiana May
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, 55108, USA
| | - Michael Millican
- Department of Plant Pathology, University of Minnesota, St. Paul, MN, 55108, USA
| | - Joslin L Moore
- Arthur Rylah Institute for Environmental Research, 123 Brown Street, Heidelberg, VIC, 3084, Australia
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, VIC, 3800, Australia
- School of Agriculture, Food and Ecosystem Sciences, The University of Melbourne, VIC, 3010, Australia
| | - Luis I Perez
- IFEVA-Facultad de Agronomía (UBA)/CONICET, Departamento de Recursos Naturales, Catedra ´ de Ecología, Av. San Martín, 4453, Buenos Aires, C1417DSE, Argentina
| | - Anita J Porath-Krause
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, 55108, USA
| | - Sally A Power
- Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | | | - Anita C Risch
- Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | - Carly Stevens
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Elizabeth T Borer
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, 55108, USA
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2
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Peters JS, Aguirre BA, DiPaola A, Power AG. Ecology of Yellow Dwarf Viruses in Crops and Grasslands: Interactions in the Context of Climate Change. ANNUAL REVIEW OF PHYTOPATHOLOGY 2022; 60:283-305. [PMID: 36027939 DOI: 10.1146/annurev-phyto-020620-101848] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Our understanding of the ecological interactions between plant viruses, their insect vectors, and their host plants has increased rapidly over the past decade. The suite of viruses known collectively as the yellow dwarf viruses infect an extensive range of cultivated and noncultivated grasses worldwide and is one of the best-studied plant virus systems. The yellow dwarf viruses are ubiquitous in cereal crops, where they can significantly limit yields, and there is growing recognition that they are also ubiquitous in grassland ecosystems, where they can influence community dynamics. Here, we discuss recent research that has explored (a) the extent and impact of yellow dwarf viruses in a diversity of plant communities, (b) the role of vector behavior in virus transmission, and (c) the prospects for impacts of climate change-including rising temperatures, drought, and elevated CO2-on the epidemiology of yellow dwarf viruses.
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Affiliation(s)
- Jasmine S Peters
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, New York, USA;
| | - Beatriz A Aguirre
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, New York, USA;
| | - Anna DiPaola
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, New York, USA;
| | - Alison G Power
- Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, New York, USA;
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3
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Sallinen S, Susi H, Halliday F, Laine AL. Altered within- and between-host transmission under coinfection underpin parasite co-occurrence patterns in the wild. Evol Ecol 2022; 37:131-151. [PMID: 36785621 PMCID: PMC9911512 DOI: 10.1007/s10682-022-10182-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 04/28/2022] [Indexed: 11/30/2022]
Abstract
Interactions among parasite species coinfecting the same host individual can have far reaching consequences for parasite ecology and evolution. How these within-host interactions affect epidemics may depend on two non-exclusive mechanisms: parasite growth and reproduction within hosts, and parasite transmission between hosts. Yet, how these two mechanisms operate under coinfection, and how sensitive they are to the composition of the coinfecting parasite community, remains poorly understood. Here, we test the hypothesis that the relationship between within- and between-host transmission of the fungal pathogen, Phomopsis subordinaria, is affected by co-occurring parasites infecting the host plant, Plantago lanceolata. We conducted a field experiment manipulating the parasite community of transmission source plants, then tracked P. subordinaria within-host transmission, as well as between-host transmission to naïve recipient plants. We find that coinfection with the powdery mildew pathogen, Podosphaera plantaginis, causes increased between-host transmission of P. subordinaria by affecting the number of infected flower stalks in the source plants, resulting from altered auto-infection. In contrast, coinfection with viruses did not have an effect on either within- or between-host transmission. We then analyzed data on the occurrence of P. subordinaria in 2018 and the powdery mildew in a multi-year survey data set from natural host populations to test whether the positive association predicted by our experimental results is evident in field epidemiological data. Consistent with our experimental findings, we observed a positive association in the occurrence of P. subordinaria and historical powdery mildew persistence. Jointly, our experimental and epidemiological results suggest that within- and between-host transmission of P. subordinaria depends on the identity of coinfecting parasites, with potentially far-reaching effects on disease dynamics and parasite co-occurrence patterns in wild populations. Supplementary Information The online version contains supplementary material available at 10.1007/s10682-022-10182-9.
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Affiliation(s)
- Suvi Sallinen
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 1 (PO box 65), 00014 Helsinki, Finland
| | - Hanna Susi
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 1 (PO box 65), 00014 Helsinki, Finland
| | - Fletcher Halliday
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, CH-8057 Zurich, Switzerland
| | - Anna-Liisa Laine
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 1 (PO box 65), 00014 Helsinki, Finland
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, CH-8057 Zurich, Switzerland
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4
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Manipulation of Insect Vectors’ Host Selection Behavior by Barley Yellow Dwarf Virus Is Dependent on the Host Plant Species and Viral Co-Infection. Life (Basel) 2022; 12:life12050644. [PMID: 35629312 PMCID: PMC9142937 DOI: 10.3390/life12050644] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 04/18/2022] [Accepted: 04/25/2022] [Indexed: 11/24/2022] Open
Abstract
Previous studies have shown that vector-borne viruses can manipulate the host selection behavior of insect vectors, yet the tripartite interactions of pathogens, host plants and insect vectors have been documented only in a limited number of pathosystems. Here, we report that the host selection behavior of the insect vector of barley yellow dwarf virus-PAV (BYDV-PAV) and cereal yellow dwarf virus-RPS (CYDV-RPS) is dependent on the host plant species and viral co-infection. This study shows that a model cereal plant, Brachypodium distachyon, is a suitable host plant for examining tripartite interactions with BYDV-PAV and CYDV-RPS. We reveal that BYDV-PAV has a different effect on the host selection behavior of its insect vector depending on the host plant species. Viruliferous aphids significantly prefer non-infected plants to virus-infected wheat plants, whereas viral infection on a novel host plant, B. distachyon, is not implicated in the attraction of either viruliferous or nonviruliferous aphids. Furthermore, our findings show that multiple virus infections of wheat with BYDV-PAV and CYDV-RPS alter the preference of their vector aphid. This result indicates that BYDV-PAV acquisition alters the insect vector’s host selection, thereby varying the spread of multiple viruses.
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5
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Easterday CA, Kendig AE, Lacroix C, Seabloom EW, Borer ET. Long-term nitrogen enrichment mediates the effects of nitrogen supply and co-inoculation on a viral pathogen. Ecol Evol 2022; 12:e8450. [PMID: 35136545 PMCID: PMC8809429 DOI: 10.1002/ece3.8450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/02/2021] [Accepted: 11/05/2021] [Indexed: 11/12/2022] Open
Abstract
Host nutrient supply can mediate host-pathogen and pathogen-pathogen interactions. In terrestrial systems, plant nutrient supply is mediated by soil microbes, suggesting a potential role of soil microbes in plant diseases beyond soil-borne pathogens and induced plant defenses. Long-term nitrogen (N) enrichment can shift pathogenic and nonpathogenic soil microbial community composition and function, but it is unclear if these shifts affect plant-pathogen and pathogen-pathogen interactions. In a growth chamber experiment, we tested the effect of long-term N enrichment on infection by Barley Yellow Dwarf Virus (BYDV-PAV) and Cereal Yellow Dwarf Virus (CYDV-RPV), aphid-vectored RNA viruses, in a grass host. We inoculated sterilized growing medium with soil collected from a long-term N enrichment experiment (ambient, low, and high N soil treatments) to isolate effects mediated by the soil microbial community. We crossed soil treatments with a N supply treatment (low, high) and virus inoculation treatment (mock-, singly-, and co-inoculated) to evaluate the effects of long-term N enrichment on plant-pathogen and pathogen-pathogen interactions, as mediated by N availability. We measured the proportion of plants infected (i.e., incidence), plant biomass, and leaf chlorophyll content. BYDV-PAV incidence (0.96) declined with low N soil (to 0.46), high N supply (to 0.61), and co-inoculation (to 0.32). Low N soil mediated the effect of N supply on BYDV-PAV: instead of N supply reducing BYDV-PAV incidence, the incidence increased. Additionally, ambient and low N soil ameliorated the negative effect of co-inoculation on BYDV-PAV incidence. BYDV-PAV infection only reduced chlorophyll when plants were grown with low N supply and ambient N soil. There were no significant effects of long-term N soil on CYDV-RPV incidence. Soil inoculant with different levels of long-term N enrichment had different effects on host-pathogen and pathogen-pathogen interactions, suggesting that shifts in soil microbial communities with long-term N enrichment may mediate disease dynamics.
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Affiliation(s)
- Casey A. Easterday
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMinnesotaUSA
- Present address:
Carlson School of ManagementUniversity of MinnesotaMinneapolisMinnesotaUSA
| | - Amy E. Kendig
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMinnesotaUSA
| | - Christelle Lacroix
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMinnesotaUSA
- Present address:
Pathologie VégétaleINRAEMontfavetFrance
| | - Eric W. Seabloom
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMinnesotaUSA
| | - Elizabeth T. Borer
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMinnesotaUSA
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6
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Strauss AT, Bowerman L, Porath‐Krause A, Seabloom EW, Borer ET. Mixed infection, risk projection, and misdirection: Interactions among pathogens alter links between host resources and disease. Ecol Evol 2021; 11:9599-9609. [PMID: 34306646 PMCID: PMC8293790 DOI: 10.1002/ece3.7781] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 05/18/2021] [Indexed: 11/27/2022] Open
Abstract
A growing body of literature links resources of hosts to their risk of infectious disease. Yet most hosts encounter multiple pathogens, and projections of disease risk based on resource availability could be fundamentally wrong if they do not account for interactions among pathogens within hosts. Here, we measured infection risk of grass hosts (Avena sativa) exposed to three naturally co-occurring viruses either singly or jointly (barley and cereal yellow dwarf viruses [B/CYDVs]: CYDV-RPV, BYDV-PAV, and BYDV-SGV) along experimental gradients of nitrogen and phosphorus supply. We asked whether disease risk (i.e., infection prevalence) differed in single versus co-inoculations, and whether these differences varied with rates and ratios of nitrogen and phosphorus supply. In single inoculations, the viruses did not respond strongly to nitrogen or phosphorus. However, in co-inoculations, we detected illustrative cases of 1) resource-dependent antagonism (lower prevalence of RPV with increasing N; possibly due to competition), 2) resource-dependent facilitation (higher prevalence of SGV with decreasing N:P; possibly due to immunosuppression), and 3) weak or no interactions within hosts (for PAV). Together, these within-host interactions created emergent patterns for co-inoculated hosts, with both infection prevalence and viral richness increasing with the combination of low nitrogen and high phosphorus supply. We demonstrate that knowledge of multiple pathogens is essential for predicting disease risk from host resources and that projections of risk that fail to acknowledge resource-dependent interactions within hosts could be qualitatively wrong. Expansions of theory from community ecology theory may help anticipate such relationships by linking host resources to diverse pathogen communities.
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Affiliation(s)
- Alexander T. Strauss
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMNUSA
- Odum School of EcologyUniversity of GeorgiaAthensGAUSA
| | - Lucas Bowerman
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMNUSA
| | - Anita Porath‐Krause
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMNUSA
| | - Eric W. Seabloom
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMNUSA
| | - Elizabeth T. Borer
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMNUSA
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7
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Susi H, Laine A. Agricultural land use disrupts biodiversity mediation of virus infections in wild plant populations. THE NEW PHYTOLOGIST 2021; 230:2447-2458. [PMID: 33341977 PMCID: PMC8248426 DOI: 10.1111/nph.17156] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/10/2020] [Indexed: 06/08/2023]
Abstract
Human alteration of natural habitats may change the processes governing species interactions in wild communities. Wild populations are increasingly impacted by agricultural intensification, yet it is unknown whether this alters biodiversity mediation of disease dynamics. We investigated the association between plant diversity (species richness, diversity) and infection risk (virus richness, prevalence) in populations of Plantago lanceolata in natural landscapes as well as those occurring at the edges of cultivated fields. Altogether, 27 P. lanceolata populations were surveyed for population characteristics and sampled for PCR detection of five recently characterized viruses. We find that plant species richness and diversity correlated negatively with virus infection prevalence. Virus species richness declined with increasing plant diversity and richness in natural populations while in agricultural edge populations species richness was moderately higher, and not associated with plant richness. This difference was not explained by changes in host richness between these two habitats, suggesting potential pathogen spill-over and increased transmission of viruses across the agro-ecological interface. Host population connectivity significantly decreased virus infection prevalence. We conclude that human use of landscapes may change the ecological laws by which natural communities are formed with far reaching implications for ecosystem functioning and disease.
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Affiliation(s)
- Hanna Susi
- Research Centre for Ecological Change, Organismal and Evolutionary Biology Research ProgrammeUniversity of HelsinkiPO Box 65Helsinki00014Finland
| | - Anna‐Liisa Laine
- Research Centre for Ecological Change, Organismal and Evolutionary Biology Research ProgrammeUniversity of HelsinkiPO Box 65Helsinki00014Finland
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichWinterthurerstrasse 190ZurichCH‐8057Switzerland
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8
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Erickson AC, Falk B. First Report of Barley virus G in the United States and California. PLANT DISEASE 2021; 105:3312. [PMID: 33904330 DOI: 10.1094/pdis-03-21-0478-pdn] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Barley (Hordeum vulgare) is a valuable annual cereal crop grown widely throughout the United States and the world. The majority of barley grown commercially in California and throughout the U.S. is used for livestock feed, with the remainder being used by the malting industry and, to a lesser extent, direct food consumption; it is also often employed as a cover crop (Lazicki et al. 2016). Yellow dwarf viruses (YDVs), in the family Luteoviridae, that infect barley and other cereal crops are common and widely distributed throughout California and the U.S. (Griesbach et al. 1989; Seabloom et al. 2009). In April 2018, five barley samples exhibiting typical symptoms of YDV infection (primarily yellowing of leaf margins and tips) collected from fields in Yolo county planted with cultivar Butta 12 , were tested for viruses. Total RNA was extracted from leaf tissue using Trizol reagent, according to the manufacturer's protocol. RNA was used as template in a multiplexed RT-PCR assay designed for the generic detection of barley and cereal infecting YDVs, using the protocol established by Malmstrom and Shu (2004). A 372 basepair amplicon indicative of Polerovirus infection was amplified from two of the samples and sequenced (Quintara Biosciences), and the resulting data analyzed via a BLASTn search. No further testing or work was done with the three samples that tested negative. Not unexpectedly, the top result returned for one of the positive samples was Cereal yellow dwarf virus-RPV (CYDV-RPV; 98% identity), a virus common to cereals in California and the U.S.. Unexpectedly, however, the top result returned for the other sample was Barley virus G (BVG), sharing 98.43% identity with the Uiseong BVG isolate (GenBank accession LC259081). To further confirm the presence of BVG in the sample, the full-length viral genome was amplified using two-step RT-PCR with primers targeting the extreme 5' and 3' ends of the viral genome, using the PrimeScript RT and PrimeSTAR GXL DNA Polymerase kits (Takara Bio), cloned into the binary vector pJL89 and a BLAST search of the resulting 5621 nucleotide full-length sequence (100% query coverage) once again returned results showing the YDV to be BVG. The full-length sequence was deposited into GenBank (MW853785). Nucleotide sequence comparisons showed that the CA BVG isolate shares 96.62%, 96.57%, and 96.02% identity with the sequences of the BVG-Gimje (KT962089), BVG-Uiseong (LC259081), and BVG-Aus8 (LC500836) isolates, respectively. To our knowledge, this is the first report of barley virus G in California and in the United states. Currently the prevalence, host range and mode and timing of introduction of BVG in California and the U.S. are unknown; its impact on cereal production and yield in any location in which it has been identified thus far is also unknown and may warrant further investigation.
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Affiliation(s)
| | - Bryce Falk
- University of California Davis, 8789, Plant Pathology, Davis, California, United States;
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9
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Pascall DJ, Tinsley MC, Clark BL, Obbard DJ, Wilfert L. Virus Prevalence and Genetic Diversity Across a Wild Bumblebee Community. Front Microbiol 2021; 12:650747. [PMID: 33967987 PMCID: PMC8100031 DOI: 10.3389/fmicb.2021.650747] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/24/2021] [Indexed: 12/16/2022] Open
Abstract
Viruses are key population regulators, but we have limited knowledge of the diversity and ecology of viruses. This is even the case in wild host populations that provide ecosystem services, where small fitness effects may have major ecological impacts in aggregate. One such group of hosts are the bumblebees, which have a major role in the pollination of food crops and have suffered population declines and range contractions in recent decades. In this study, we investigate the diversity of four recently discovered bumblebee viruses (Mayfield virus 1, Mayfield virus 2, River Liunaeg virus, and Loch Morlich virus), and two previously known viruses that infect both wild bumblebees and managed honeybees (Acute bee paralysis virus and Slow bee paralysis virus) from isolates in Scotland. We investigate the ecological and environmental factors that determine viral presence and absence. We show that the recently discovered bumblebee viruses were more genetically diverse than the viruses shared with honeybees. Coinfection is potentially important in shaping prevalence: we found a strong positive association between River Liunaeg virus and Loch Morlich virus presence after controlling for host species, location and other relevant ecological variables. We tested for a relationship between environmental variables (temperature, UV radiation, wind speed, and prevalence), but as we had few sampling sites, and thus low power for site-level analyses, we could not conclude anything regarding these variables. We also describe the relationship between the bumblebee communities at our sampling sites. This study represents a first step in the description of predictors of bumblebee infection in the wild.
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Affiliation(s)
- David J. Pascall
- Institute of Biodiversity, Animal Health and Comparative Medicine, Boyd Orr Centre for Population and Ecosystem Health, University of Glasgow, Glasgow, United Kingdom
- Centre for Ecology and Conservation, University of Exeter, Cornwall, United Kingdom
| | - Matthew C. Tinsley
- Biological and Environmental Sciences, University of Stirling, Stirling, United Kingdom
| | - Bethany L. Clark
- BirdLife International, The David Attenborough Building, Cambridge, United Kingdom
- Environment and Sustainability Institute, University of Exeter, Cornwall, United Kingdom
| | - Darren J. Obbard
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Lena Wilfert
- Centre for Ecology and Conservation, University of Exeter, Cornwall, United Kingdom
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Ulm, Germany
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Sallinen S, Norberg A, Susi H, Laine AL. Intraspecific host variation plays a key role in virus community assembly. Nat Commun 2020; 11:5610. [PMID: 33154373 PMCID: PMC7644774 DOI: 10.1038/s41467-020-19273-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 10/05/2020] [Indexed: 12/31/2022] Open
Abstract
Infection by multiple pathogens of the same host is ubiquitous in both natural and managed habitats. While intraspecific variation in disease resistance is known to affect pathogen occurrence, how differences among host genotypes affect the assembly of pathogen communities remains untested. In our experiment using cloned replicates of naive Plantago lanceolata plants as sentinels during a seasonal virus epidemic, we find non-random co-occurrence patterns of five focal viruses. Using joint species distribution modelling, we attribute the non-random virus occurrence patterns primarily to differences among host genotypes and local population context. Our results show that intraspecific variation among host genotypes may play a large, previously unquantified role in pathogen community structure.
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Affiliation(s)
- Suvi Sallinen
- Organismal and Evolutionary Biology Research Programme, Viikinkaari 1 (PO box 65), FI-00014, University of Helsinki, Helsinki, Finland.
| | - Anna Norberg
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, CH-8067, Zürich, Switzerland
| | - Hanna Susi
- Organismal and Evolutionary Biology Research Programme, Viikinkaari 1 (PO box 65), FI-00014, University of Helsinki, Helsinki, Finland
| | - Anna-Liisa Laine
- Organismal and Evolutionary Biology Research Programme, Viikinkaari 1 (PO box 65), FI-00014, University of Helsinki, Helsinki, Finland
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, CH-8067, Zürich, Switzerland
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11
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Modelling Vector Transmission and Epidemiology of Co-Infecting Plant Viruses. Viruses 2019; 11:v11121153. [PMID: 31847125 PMCID: PMC6950130 DOI: 10.3390/v11121153] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/03/2019] [Accepted: 12/06/2019] [Indexed: 12/24/2022] Open
Abstract
Co-infection of plant hosts by two or more viruses is common in agricultural crops and natural plant communities. A variety of models have been used to investigate the dynamics of co-infection which track only the disease status of infected and co-infected plants, and which do not explicitly track the density of inoculative vectors. Much less attention has been paid to the role of vector transmission in co-infection, that is, acquisition and inoculation and their synergistic and antagonistic interactions. In this investigation, a general epidemiological model is formulated for one vector species and one plant species with potential co-infection in the host plant by two viruses. The basic reproduction number provides conditions for successful invasion of a single virus. We derive a new invasion threshold which provides conditions for successful invasion of a second virus. These two thresholds highlight some key epidemiological parameters important in vector transmission. To illustrate the flexibility of our model, we examine numerically two special cases of viral invasion. In the first case, one virus species depends on an autonomous virus for its successful transmission and in the second case, both viruses are unable to invade alone but can co-infect the host plant when prevalence is high.
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12
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Hamelin FM, Allen LJS, Bokil VA, Gross LJ, Hilker FM, Jeger MJ, Manore CA, Power AG, Rúa MA, Cunniffe NJ. Coinfections by noninteracting pathogens are not independent and require new tests of interaction. PLoS Biol 2019; 17:e3000551. [PMID: 31794547 PMCID: PMC6890165 DOI: 10.1371/journal.pbio.3000551] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 11/04/2019] [Indexed: 12/26/2022] Open
Abstract
If pathogen species, strains, or clones do not interact, intuition suggests the proportion of coinfected hosts should be the product of the individual prevalences. Independence consequently underpins the wide range of methods for detecting pathogen interactions from cross-sectional survey data. However, the very simplest of epidemiological models challenge the underlying assumption of statistical independence. Even if pathogens do not interact, death of coinfected hosts causes net prevalences of individual pathogens to decrease simultaneously. The induced positive correlation between prevalences means the proportion of coinfected hosts is expected to be higher than multiplication would suggest. By modelling the dynamics of multiple noninteracting pathogens causing chronic infections, we develop a pair of novel tests of interaction that properly account for nonindependence between pathogens causing lifelong infection. Our tests allow us to reinterpret data from previous studies including pathogens of humans, plants, and animals. Our work demonstrates how methods to identify interactions between pathogens can be updated using simple epidemic models. If pathogen species, strains, or clones do not interact, intuition suggests the proportion of coinfected hosts can be obtained by simply multiplying the individual prevalences. However, even simple epidemiological models show this to be untrue. This study develops new tests for interaction between pathogens that account for this surprising lack of statistical independence.
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Affiliation(s)
- Frédéric M. Hamelin
- IGEPP, Agrocampus Ouest, INRA, Université de Rennes 1, Université Bretagne-Loire, Rennes, France
| | - Linda J. S. Allen
- Department of Mathematics and Statistics, Texas Tech University, Lubbock, Texas, United States of America
| | - Vrushali A. Bokil
- Department of Mathematics, Oregon State University, Corvallis, Oregon, United States of America
| | - Louis J. Gross
- National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Frank M. Hilker
- Institute of Environmental Systems Research, School of Mathematics and Computer Science, Osnabrück University, Osnabrück, Germany
| | - Michael J. Jeger
- Centre for Environmental Policy, Imperial College London, Ascot, United Kingdom
| | - Carrie A. Manore
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Alison G. Power
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, United States of America
| | - Megan A. Rúa
- Department of Biological Sciences, Wright State University, Dayton, Ohio, United States of America
| | - Nik J. Cunniffe
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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13
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McLeish M, Sacristán S, Fraile A, García-Arenal F. Coinfection Organizes Epidemiological Networks of Viruses and Hosts and Reveals Hubs of Transmission. PHYTOPATHOLOGY 2019; 109:1003-1010. [PMID: 30540552 DOI: 10.1094/phyto-08-18-0293-r] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Multiple virus infections affect the competence of host plants to transmit disease. The effects of coinfection on transmission are expected to produce ecologically complex pathogen and host-pathogen interactions. However, the prediction of disease risk will rely on untangling nonrandom from random patterns of infection to identify underlying processes that drive these interactions. Are the spatial distributions of infections in complex multispecies systems random or not? For the first time, we use an empirical evaluation of this basic but nontrivial question to test the hypothesis that coinfection contributes to (i) nonrandom ecological interactions between hosts and viruses and (ii) structuring infection distributions. We use a novel approach that decomposed the ecological interactions of 11 generalist viruses in 47 host species in four habitats of an agroecosystem into single-infection and coinfection "modes." Then, we relate ecological structuring in infection networks to the distribution of infection using generalized regression models. The network analyses of coinfection showed that virus-host interactions occurred more often than expected at random in one of the four habitats, Edge. A pattern of specific interactions was shared between Edge and the ecosystem, indicating scale invariance. The regression modeling also showed that the plant community characteristics of Edge were unique in explaining infection distributions. The results showed that the spatial distribution of infection at the ecosystem level was not only a species-specific phenomenon but also, strongly structured by specific virus-virus and host-virus interactions. The evidence of scale invariance and the special role of Edge as a reservoir suggest that ecological interactions were less strongly structured by community differences among habitats than by wider-scale processes and traits underlying the interactions. Addressing whether reservoir communities significantly contribute to epidemiological processes at the ecosystem scale is a promising avenue for future research.
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Affiliation(s)
- Michael McLeish
- Centro de Biotecnología y Genómica de Plantas Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Soledad Sacristán
- Centro de Biotecnología y Genómica de Plantas Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid 28223, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid 28223, Spain
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14
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Evolution of plant-virus interactions: host range and virus emergence. Curr Opin Virol 2019; 34:50-55. [PMID: 30654270 DOI: 10.1016/j.coviro.2018.12.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/11/2018] [Indexed: 12/11/2022]
Abstract
Changes in host range are central to virus emergence. Host range, together with its evolution, is determined by virus intrinsic factors, such as genetic traits determining its fitness in different hosts. Experimental analyses have shown the relevance in host range evolution of across-host fitness trade-offs. Host range is also determined by ecological factors extrinsic to the virus such as the distribution, abundance, and interaction of species, and understanding their role in host range evolution is a current challenge. Indeed, intrinsic and extrinsic factors, and the complexity of biotic and abiotic interactions, must be considered in order to provide generalisations on patterns of transmission, host range evolution, and disease emergence. This exciting new field of research is still in its infancy.
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15
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Susi H, Filloux D, Frilander MJ, Roumagnac P, Laine AL. Diverse and variable virus communities in wild plant populations revealed by metagenomic tools. PeerJ 2019; 7:e6140. [PMID: 30648011 PMCID: PMC6330959 DOI: 10.7717/peerj.6140] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/20/2018] [Indexed: 12/21/2022] Open
Abstract
Wild plant populations may harbour a myriad of unknown viruses. As the majority of research efforts have targeted economically important plant species, the diversity and prevalence of viruses in the wild has remained largely unknown. However, the recent shift towards metagenomics-based sequencing methodologies, especially those targeting small RNAs, is finally enabling virus discovery from wild hosts. Understanding this diversity of potentially pathogenic microbes in the wild can offer insights into the components of natural biodiversity that promotes long-term coexistence between hosts and parasites in nature, and help predict when and where risks of disease emergence are highest. Here, we used small RNA deep sequencing to identify viruses in Plantago lanceolata populations, and to understand the variation in their prevalence and distribution across the Åland Islands, South-West Finland. By subsequent design of PCR primers, we screened the five most common viruses from two sets of P. lanceolata plants: 164 plants collected from 12 populations irrespective of symptoms, and 90 plants collected from five populations showing conspicuous viral symptoms. In addition to the previously reported species Plantago lanceolata latent virus (PlLV), we found four potentially novel virus species belonging to Caulimovirus, Betapartitivirus, Enamovirus, and Closterovirus genera. Our results show that virus prevalence and diversity varied among the sampled host populations. In six of the virus infected populations only a single virus species was detected, while five of the populations supported between two to five of the studied virus species. In 20% of the infected plants, viruses occurred as coinfections. When the relationship between conspicuous viral symptoms and virus infection was investigated, we found that plants showing symptoms were usually infected (84%), but virus infections were also detected from asymptomatic plants (44%). Jointly, these results reveal a diverse virus community with newly developed tools and protocols that offer exciting opportunities for future studies on the eco-evolutionary dynamics of viruses infecting plants in the wild.
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Affiliation(s)
- Hanna Susi
- Research Centre for Ecological Change, Organismal and Evolutionary Biology Research Programme, University of Helsinki, Finland
| | - Denis Filloux
- CIRAD, BGPI, Montpellier, France.,BGPI, INRA, CIRAD, SupAgro, University Montpellier, Montpellier, France
| | - Mikko J Frilander
- Institute of Biotechnology, Genome Biology Program, University of Helsinki, Finland
| | - Philippe Roumagnac
- CIRAD, BGPI, Montpellier, France.,BGPI, INRA, CIRAD, SupAgro, University Montpellier, Montpellier, France
| | - Anna-Liisa Laine
- Research Centre for Ecological Change, Organismal and Evolutionary Biology Research Programme, University of Helsinki, Finland
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16
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McLeish M, Sacristán S, Fraile A, García-Arenal F. Scale dependencies and generalism in host use shape virus prevalence. Proc Biol Sci 2018; 284:rspb.2017.2066. [PMID: 29263286 DOI: 10.1098/rspb.2017.2066] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/20/2017] [Indexed: 01/01/2023] Open
Abstract
Processes that generate the distribution of pathogens and their interactions with hosts are not insensitive to changes in spatial scale. Spatial scales and species traits are often selected intentionally, based on practical considerations, ignoring biases that the scale and type of observation may introduce. Specifically, these biases might change the interpretation of disease-diversity relationships that are reported as either 'dilution' or 'amplification' effects. Here, we combine field data of a host-pathogen community with empirical models to test the effects that (i) spatial scale and (ii) host range have on the relationship between plant-virus infection prevalence and diversity. We show that prevalence-diversity relationships are scale-dependent and can produce opposite effects associated with different habitats at sub-ecosystem scales. The total number of host species of each virus reflected generalism at the ecosystem scale. However, plasticity in host range resembled habitat-specific specialization and also changed model predictions. We show that habitat heterogeneity, ignored at larger (ecosystem) spatial scales, influences pathogen distributions. Hence, understanding disease distributions and the evolution of pathogens requires reconciling specific hypotheses of the study with an appropriate spatial scale, or scales, and consideration of traits, such as host range, that might strongly contribute to biotic interactions.
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Affiliation(s)
- Michael McLeish
- Centro de Biotecnología y Genómica de Plantas UPM-INIA and Escuela Técnica Superior de Ingeniería Agronómica, Agroambiental y de Biosistemas (ETSIAAB), Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, Madrid 28223, Spain
| | - Soledad Sacristán
- Centro de Biotecnología y Genómica de Plantas UPM-INIA and Escuela Técnica Superior de Ingeniería Agronómica, Agroambiental y de Biosistemas (ETSIAAB), Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, Madrid 28223, Spain
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas UPM-INIA and Escuela Técnica Superior de Ingeniería Agronómica, Agroambiental y de Biosistemas (ETSIAAB), Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, Madrid 28223, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas UPM-INIA and Escuela Técnica Superior de Ingeniería Agronómica, Agroambiental y de Biosistemas (ETSIAAB), Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, Madrid 28223, Spain
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17
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McLeish MJ, Fraile A, García-Arenal F. Ecological Complexity in Plant Virus Host Range Evolution. Adv Virus Res 2018; 101:293-339. [PMID: 29908592 DOI: 10.1016/bs.aivir.2018.02.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The host range of a plant virus is the number of species in which it can reproduce. Most studies of plant virus host range evolution have focused on the genetics of host-pathogen interactions. However, the distribution and abundance of plant viruses and their hosts do not always overlap, and these spatial and temporal discontinuities in plant virus-host interactions can result in various ecological processes that shape host range evolution. Recent work shows that the distributions of pathogenic and resistant genotypes, vectors, and other resources supporting transmission vary widely in the environment, producing both expected and unanticipated patterns. The distributions of all of these factors are influenced further by competitive effects, natural enemies, anthropogenic disturbance, the abiotic environment, and herbivory to mention some. We suggest the need for further development of approaches that (i) explicitly consider resource use and the abiotic and biotic factors that affect the strategies by which viruses exploit resources; and (ii) are sensitive across scales. Host range and habitat specificity will largely determine which phyla are most likely to be new hosts, but predicting which host and when it is likely to be infected is enormously challenging because it is unclear how environmental heterogeneity affects the interactions of viruses and hosts.
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Affiliation(s)
- Michael J McLeish
- Centro de Biotecnología y Genómica de Plantas UPM-INIA, and E.T.S.I. Agrícola, Alimentaria y de Biosistemas, Campus de Montegancedo, Universidad Politécnica de Madrid, Madrid, Spain
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas UPM-INIA, and E.T.S.I. Agrícola, Alimentaria y de Biosistemas, Campus de Montegancedo, Universidad Politécnica de Madrid, Madrid, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas UPM-INIA, and E.T.S.I. Agrícola, Alimentaria y de Biosistemas, Campus de Montegancedo, Universidad Politécnica de Madrid, Madrid, Spain.
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18
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Marchetto KM, Power AG. Coinfection Timing Drives Host Population Dynamics through Changes in Virulence. Am Nat 2017; 191:173-183. [PMID: 29351014 DOI: 10.1086/695316] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Infections of one host by multiple parasites are common, and several studies have found that the order of parasite invasion can affect both within-host competition and disease severity. However, it is unclear to what extent coinfection timing might be important to consider when modeling parasite impacts on host populations. Using a model system of two viruses infecting barley, we found that simultaneous infections of the two viruses were significantly more damaging to hosts than sequential coinfections. While priority effects were evident in within-host concentrations of sequential coinfections, priority did not influence any parameters (such as virulence or transmission rate) that affect host population dynamics. We built a susceptible-infected model to examine whether the observed difference in coinfection virulence could impact host population dynamics under a range of scenarios. We found that coinfection timing can have an important but context-dependent effect on projected host population dynamics. Studies that examine only simultaneous coinfections could inflate disease impact predictions.
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19
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Lacroix C, Seabloom EW, Borer ET. Environmental Nutrient Supply Directly Alters Plant Traits but Indirectly Determines Virus Growth Rate. Front Microbiol 2017; 8:2116. [PMID: 29163408 PMCID: PMC5681519 DOI: 10.3389/fmicb.2017.02116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 10/17/2017] [Indexed: 11/13/2022] Open
Abstract
Ecological stoichiometry and resource competition theory both predict that nutrient rates and ratios can alter infectious disease dynamics. Pathogens such as viruses hijack nutrient rich host metabolites to complete multiple steps of their epidemiological cycle. As the synthesis of these molecules requires nitrogen (N) and phosphorus (P), environmental supply rates, and ratios of N and P to hosts can directly limit disease dynamics. Environmental nutrient supplies also may alter virus epidemiology indirectly by changing host phenotype or the dynamics of coinfecting pathogens. We tested whether host nutrient supplies and coinfection control pathogen growth within hosts and transmission to new hosts, either directly or through modifications of plant tissue chemistry (i.e., content and stoichiometric ratios of nutrients), host phenotypic traits, or among-pathogen interactions. We examined two widespread plant viruses (BYDV-PAV and CYDV-RPV) in cultivated oats (Avena sativa) grown along a range of N and of P supply rates. N and P supply rates altered plant tissue chemistry and phenotypic traits; however, environmental nutrient supplies and plant tissue content and ratios of nutrients did not directly alter virus titer. Infection with CYDV-RPV altered plant traits and resulted in thicker plant leaves (i.e., higher leaf mass per area) and there was a positive correlation between CYDV-RPV titer and leaf mass per area. CYDV-RPV titer was reduced by the presence of a competitor, BYDV-PAV, and higher CYDV-RPV titer led to more severe chlorotic symptoms. In our experimental conditions, virus transmission was unaffected by nutrient supply rates, co-infection, plant stoichiometry, or plant traits, although nutrient supply rates have been shown to increase infection and coinfection rates. This work provides a robust test of the role of plant nutrient content and ratios in the dynamics of globally important pathogens and reveals a more complex relationship between within-host virus growth and alterations of plant traits. A deeper understanding of the differential effects of environmental nutrient supplies on virus epidemiology and ecology is particularly relevant given the rapid increase of nutrients flowing into Earth's ecosystems as a result of human activities.
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20
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Tugume AK, Mukasa SB, Valkonen JPT. Mixed Infections of Four Viruses, the Incidence and Phylogenetic Relationships of Sweet Potato Chlorotic Fleck Virus (Betaflexiviridae) Isolates in Wild Species and Sweetpotatoes in Uganda and Evidence of Distinct Isolates in East Africa. PLoS One 2016; 11:e0167769. [PMID: 28005969 PMCID: PMC5179071 DOI: 10.1371/journal.pone.0167769] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 11/18/2016] [Indexed: 01/05/2023] Open
Abstract
Viruses infecting wild flora may have a significant negative impact on nearby crops, and vice-versa. Only limited information is available on wild species able to host economically important viruses that infect sweetpotatoes (Ipomoea batatas). In this study, Sweet potato chlorotic fleck virus (SPCFV; Carlavirus, Betaflexiviridae) and Sweet potato chlorotic stunt virus (SPCSV; Crinivirus, Closteroviridae) were surveyed in wild plants of family Convolvulaceae (genera Astripomoea, Ipomoea, Hewittia and Lepistemon) in Uganda. Plants belonging to 26 wild species, including annuals, biannuals and perennials from four agro-ecological zones, were observed for virus-like symptoms in 2004 and 2007 and sampled for virus testing. SPCFV was detected in 84 (2.9%) of 2864 plants tested from 17 species. SPCSV was detected in 66 (5.4%) of the 1224 plants from 12 species sampled in 2007. Some SPCSV-infected plants were also infected with Sweet potato feathery mottle virus (SPFMV; Potyvirus, Potyviridae; 1.3%), Sweet potato mild mottle virus (SPMMV; Ipomovirus, Potyviridae; 0.5%) or both (0.4%), but none of these three viruses were detected in SPCFV-infected plants. Co-infection of SPFMV with SPMMV was detected in 1.2% of plants sampled. Virus-like symptoms were observed in 367 wild plants (12.8%), of which 42 plants (11.4%) were negative for the viruses tested. Almost all (92.4%) the 419 sweetpotato plants sampled from fields close to the tested wild plants displayed virus-like symptoms, and 87.1% were infected with one or more of the four viruses. Phylogenetic and evolutionary analyses of the 3'-proximal genomic region of SPCFV, including the silencing suppressor (NaBP)- and coat protein (CP)-coding regions implicated strong purifying selection on the CP and NaBP, and that the SPCFV strains from East Africa are distinguishable from those from other continents. However, the strains from wild species and sweetpotato were indistinguishable, suggesting reciprocal movement of SPCFV between wild and cultivated Convolvulaceae plants in the field.
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Affiliation(s)
- Arthur K. Tugume
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
- Department of Plant Sciences, Microbiology and Biotechnology, School of Biosciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Settumba B. Mukasa
- Department of Agricultural Production, School of Agricultural Sciences, College of Agricultural and Environmental Sciences, Makerere University, Kampala, Uganda
| | - Jari P. T. Valkonen
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
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21
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Borer ET, Laine AL, Seabloom EW. A Multiscale Approach to Plant Disease Using the Metacommunity Concept. ANNUAL REVIEW OF PHYTOPATHOLOGY 2016; 54:397-418. [PMID: 27296140 DOI: 10.1146/annurev-phyto-080615-095959] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Plant disease arises from the interaction of processes occurring at multiple spatial and temporal scales. With new tools such as next-generation sequencing, we are learning about the diversity of microbes circulating within and among plant populations and often coinhabiting host individuals. The proliferation of pathogenic microbes depends on single-species dynamics and multispecies interactions occurring within and among host cells, the spatial organization and genetic landscape of hosts, the frequency and mode of transmission among hosts and host populations, and the abiotic environmental context. Here, we examine empirical evidence from these multiple scales to assess the utility of metacommunity theory, a theoretical framework developed for free-living organisms to further our understanding of and assist in predicting plant-pathogen infection and spread. We suggest that deeper understanding of disease dynamics can arise through the application of this conceptual framework at scales ranging from individual cells to landscapes. In addition, we use this multiscale theoretical perspective to synthesize existing knowledge, generate novel hypotheses, and point toward promising future opportunities for the study of plant pathogens in natural populations.
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Affiliation(s)
- Elizabeth T Borer
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108; ,
| | - Anna-Liisa Laine
- Centre of Excellence in Metapopulation Biology, Department of Biosciences, University of Helsinki, FI-00014, Finland;
| | - Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108; ,
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22
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Trypanosoma cruzi and Trypanosoma rangeli co-infection patterns in insect vectors vary across habitat types in a fragmented forest landscape. ACTA ACUST UNITED AC 2016. [DOI: 10.1017/pao.2016.9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
SUMMARYThe transmission of parasites can be influenced by their co-occurrence with other parasites, in some cases increasing or reducing transmission.Trypanosoma cruzi, aetiologic agent of Chagas disease, often co-occurs withTrypanosoma rangeli, a parasite not pathogenic for mammal hosts. Both parasites can reduce the fitness of their insect vectors (the triatomine bugs; Hemiptera: Reduviidae), withT. rangelibeing more pathogenic for some species. Here, we study the prevalence ofT. cruziandT. rangeliin the triatomineRhodnius pallescensacross a heterogeneously transformed landscape in Panamá. We found that singleT. rangeliinfections were more common in contiguously forested habitats, while singleT. cruziinfections predominated in anthropogenically disturbed habitats.Trypanosoma cruzi–T. rangelico-infections were more common in contiguous forests and in peridomiciliary areas. Furthermore, adult insects were more likely to be co-infected than nymphs. Our results suggest that human-mediated landscape transformation might have increased the predominance of single infections withT. cruziwithin vectors. An important mechanism driving changes in trypanosome infection patterns in triatomines at a landscape scale includes alterations in host species composition that may vary with different degrees of deforestation. Trypanosome co-infection may also confer a survival advantage forR. pallescensto and/or throughout adulthood.
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23
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Tollenaere C, Susi H, Laine AL. Evolutionary and Epidemiological Implications of Multiple Infection in Plants. TRENDS IN PLANT SCIENCE 2016; 21:80-90. [PMID: 26651920 DOI: 10.1016/j.tplants.2015.10.014] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 10/02/2015] [Accepted: 10/20/2015] [Indexed: 05/04/2023]
Abstract
Recent methodological advances have uncovered tremendous microbial diversity cohabiting in the same host plant, and many of these microbes cause disease. In this review we highlight how the presence of other pathogen species, or other pathogen genotypes, within a plant can affect key components of host-pathogen interactions: (i) within-plant virulence and pathogen accumulation, through direct and host-mediated mechanisms; (ii) evolutionary trajectories of pathogen populations, through virulence evolution, generation of novel genetic combinations, and maintenance of genetic diversity; and (iii) disease dynamics, with multiple infection likely to render epidemics more devastating. The major future challenges are to couple a community ecology approach with a molecular investigation of the mechanisms operating under coinfection and to evaluate the evolution and effectiveness of resistance within a coinfection framework.
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Affiliation(s)
- Charlotte Tollenaere
- Interactions Plantes-Microorganismes et Environnement (IPME), Institut de Recherches pour le Développement (IRD) - Cirad - Université de Montpellier, 34394 Montpellier, France; Laboratoire Mixte International Patho-Bios, IRD-INERA (Institut de l'Environnement et de Recherches Agricoles), BP171, Bobo-Dioulasso, Burkina Faso
| | - Hanna Susi
- Metapopulation Research Centre, Department of Biosciences, PO Box 65 (Viikinkaari 1), FI-00014 University of Helsinki, Helsinki, Finland
| | - Anna-Liisa Laine
- Metapopulation Research Centre, Department of Biosciences, PO Box 65 (Viikinkaari 1), FI-00014 University of Helsinki, Helsinki, Finland.
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24
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Mordecai EA, Gross K, Mitchell CE. Within-Host Niche Differences and Fitness Trade-offs Promote Coexistence of Plant Viruses. Am Nat 2016; 187:E13-26. [DOI: 10.1086/684114] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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25
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Prager SM, Wallis C, Trumble JT. Indirect Effects of One Plant Pathogen on the Transmission of a Second Pathogen and the Behavior of its Potato Psyllid Vector. ENVIRONMENTAL ENTOMOLOGY 2015; 44:1065-1075. [PMID: 26314051 DOI: 10.1093/ee/nvv081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/01/2015] [Indexed: 06/04/2023]
Abstract
Plant pathogens can influence the behavior and performance of insect herbivores. Studies of these associations typically focus on tripartite interactions between a plant host, a plant pathogen, and its insect vector. An unrelated herbivore or pathogen might influence such interactions. This study used a model system consisting of Tobacco mosaic virus (TMV), the psyllid Bactericera cockerelli Sulc, and tomatoes to investigate multipartite interactions among a pathogen, a nonvector, and a plant host, and determine whether shifts in host physiology were behind potential interactions. Additionally, the ability of TMV to affect the success of another pathogen, 'Candidatus Liberibacter solanacearum,' which is transmitted by the psyllid, was studied. In choice trials, psyllids preferred nearly fourfold noninfected plants to TMV-infected plants. No-choice bioassays demonstrated that there was no difference in psyllid development between TMV-infected and control plants; oviposition was twice as high on control plants. Following inoculation by psyllids, 'Candidatus Liberibacter solanacearum' titers were lower in TMV-infected plants than control plants. TMV-infected plants had lower levels of amino acids and sugars but little differences in phenolics and terpenoids, relative to control plants. Possibly, these changes in sugars are associated with a reduction in psyllid attractiveness in TMV-infected tomatoes resulting in decreased infection of 'Candidatus Liberibacter solanacearum.'
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Affiliation(s)
- Sean M Prager
- Department of Entomology, University of California, Riverside, Riverside, CA.
| | | | - John T Trumble
- Department of Entomology, University of California, Riverside, Riverside, CA
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26
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Blaisdell GK, Zhang S, Bratburd JR, Daane KM, Cooper ML, Almeida RPP. Interactions Within Susceptible Hosts Drive Establishment of Genetically Distinct Variants of an Insect-Borne Pathogen. JOURNAL OF ECONOMIC ENTOMOLOGY 2015; 108:1531-1539. [PMID: 26470292 DOI: 10.1093/jee/tov153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 05/15/2015] [Indexed: 06/05/2023]
Abstract
Coinfections are common, leading to pathogen interactions during transmission and establishment in a host. However, few studies have tested the relative strengths of pathogen interactions in vectors and hosts that determine the outcome of infection. We tested interactions between two genetically distinct variants of the mealybug-transmitted Grapevine leafroll-associated virus 3. The transmission efficiency of each variant in single variant inoculations by two vector species was determined. The effects of vector species, a coinfected source, and simultaneous inoculation from multiple hosts to one host on variant establishment were examined. Within-vector interactions could have a role in transmission from hosts containing mixed infections, but not when vectors were moved from separate singly infected source plants to a single recipient plant. The invasive Planococcus ficus (Signoret) was a more efficient vector than Pseudococcus viburni (Signoret). Transmission efficiency of the two variants did not differ in single variant inoculations. Overall infections were the same whether from singly or coinfected source plants. In mixed inoculations, establishment of one variant was reduced. Mixed inoculations from two singly infected source plants resulted in fewer mixed infections than expected by chance. Therefore, the observed outcome was determined subsequent to host inoculation rather than in the vector. The outcome may be due to resource competition between pathogens. Alternatively apparent competition may be responsible; the pathogens' differential ability to overcome host defenses and colonize the host may determine the final outcome of new infections. Detailed knowledge of interactions between pathogens during transmission and establishment could improve understanding and management of disease spread.
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Affiliation(s)
- G K Blaisdell
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - S Zhang
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - J R Bratburd
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - K M Daane
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - M L Cooper
- Division of Agriculture and Natural Resources, University of California, UC Cooperative Extension, 1710 Soscol Ave., Suite 4, Napa, CA 94559
| | - R P P Almeida
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720.
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Mordecai EA, Hindenlang M, Mitchell CE. Differential Impacts of Virus Diversity on Biomass Production of a Native and an Exotic Grass Host. PLoS One 2015; 10:e0134355. [PMID: 26230720 PMCID: PMC4521826 DOI: 10.1371/journal.pone.0134355] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 07/09/2015] [Indexed: 12/12/2022] Open
Abstract
Pathogens are common and diverse in natural communities and have been implicated in the success of host invasions. Yet few studies have experimentally measured how pathogens impact native versus exotic hosts, particularly when individual hosts are simultaneously coinfected by diverse pathogens. To estimate effects of interactions among multiple pathogens within host individuals on both transmission of pathogens and fitness consequences for hosts, we conducted a greenhouse experiment using California grassland species: the native perennial grass Nassella (Stipa) pulchra, the exotic annual grass Bromus hordeaceus, and three virus species, Barley yellow dwarf virus-PAV, Barley yellow dwarf virus-MAV, and Cereal yellow dwarf virus-RPV. In terms of virus transmission, the native host was less susceptible than the exotic host to MAV. Coinfection of PAV and MAV did not occur in any of the 157 co-inoculated native host plants. In the exotic host, PAV infection most strongly reduced root and shoot biomass, and coinfections that included PAV severely reduced biomass. Infection with single or multiple viruses did not affect biomass in the native host. However, in this species the most potentially pathogenic coinfections (PAV + MAV and PAV + MAV + RPV) did not occur. Together, these results suggest that interactions among multiple pathogens can have important consequences for host health, which may not be predictable from interactions between hosts and individual pathogens. This work addresses a key empirical gap in understanding the impact of multiple generalist pathogens on competing host species, with potential implications for population and community dynamics of native and exotic species. It also demonstrates how pathogens with relatively mild impacts independently can more substantially reduce host performance in coinfection.
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Affiliation(s)
- Erin A. Mordecai
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Madeleine Hindenlang
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Charles E. Mitchell
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
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Angelella GM, Egel DS, Holland JD, Nemacheck JA, Williams CE, Kaplan I. Differential Life History Trait Associations of Aphids with Nonpersistent Viruses in Cucurbits. ENVIRONMENTAL ENTOMOLOGY 2015; 44:562-573. [PMID: 26313961 DOI: 10.1093/ee/nvv058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 03/23/2015] [Indexed: 06/04/2023]
Abstract
The diversity of vectors and fleeting nature of virus acquisition and transmission renders nonpersistent viruses a challenge to manage. We assessed the importance of noncolonizing versus colonizing vectors with a 2-yr survey of aphids and nonpersistent viruses on commercial pumpkin farms. We quantified aphid alightment using pan traps, while testing leaf samples with multiplex RT-PCR targeting cucumber mosaic virus (CMV), zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV), and papaya ringspot virus (PRSV). Overall, we identified 53 aphid species (3,899 individuals), from which the melon aphid, Aphis gossypii Glover, a pumpkin-colonizing species, predominated (76 and 37% of samples in 2010 and 2011, respectively). CMV and ZYMV were not detected, but WMV and PRSV were prevalent, both regionally (WMV: 28/29 fields, PRSV: 21/29 fields) and within fields (infection rates = 69 and 55% for WMV in 2010 and 2011; 28 and 25% for PRSV in 2010 and 2011). However, early-season samples showed extremely low infection levels, suggesting cucurbit viruses are not seed-transmitted and implicating aphid activity as a causal factor driving virus spread. Interestingly, neither noncolonizer and colonizer alightment nor total aphid alightment were good predictors of virus presence, but community analyses revealed species-specific relationships. For example, cowpea aphid (Aphis craccivora Koch) and spotted alfalfa aphid (Therioaphis trifolii Monell f. maculata) were associated with PRSV infection, whereas the oleander aphid (Aphis nerii Bover de Fonscolombe) was associated with WMV spread within fields. These outcomes highlight the need for tailored management plans targeting key vectors of nonpersistent viruses in agricultural systems.
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Affiliation(s)
- G M Angelella
- Department of Entomology, Purdue University, 901 West State St., West Lafayette, IN 47907.
| | - D S Egel
- Southwest-Purdue Agricultural Center, 4669 North Purdue Rd., Vincennes, IN 47591
| | - J D Holland
- Department of Entomology, Purdue University, 901 West State St., West Lafayette, IN 47907
| | - J A Nemacheck
- USDA-ARS Crop Production and Pest Control Research Unit, Purdue University, 170 South University St., West Lafayette, IN 47907. Department of Agronomy, Purdue University, 915 West State St., West Lafayette, IN 47907
| | - C E Williams
- USDA-ARS Crop Production and Pest Control Research Unit, Purdue University, 170 South University St., West Lafayette, IN 47907. Department of Agronomy, Purdue University, 915 West State St., West Lafayette, IN 47907
| | - I Kaplan
- Department of Entomology, Purdue University, 901 West State St., West Lafayette, IN 47907
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29
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Ma G, Rudolf VHW, Ma CS. Extreme temperature events alter demographic rates, relative fitness, and community structure. GLOBAL CHANGE BIOLOGY 2015; 21:1794-1808. [PMID: 24909842 DOI: 10.1111/gcb.12654] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 04/23/2014] [Accepted: 05/27/2014] [Indexed: 05/28/2023]
Abstract
The frequency and magnitude of extreme events are predicted to increase under future climate change. Despite recent advancements, we still lack a detailed understanding of how changes in the frequency and amplitude of extreme climate events are linked to the temporal and spatial structure of natural communities. To answer this question, we used a combination of laboratory experiments, field experiments, and analysis of multi-year field observations to reveal the effects of extreme high temperature events on the demographic rates and relative dominance of three co-occurrence aphid species which differ in their transmission efficiency of different agricultural pathogens. We then linked the geographical shift in their relative dominance to frequent extreme high temperatures through a meta-analysis. We found that both frequency and amplitude of extreme high temperatures altered demographic rates of species. However, these effects were species-specific. Increasing the frequency and amplitude of extreme temperature events altered which species had the highest fitness. Importantly, this change in relative fitness of species was consistent with significant changes in the relative dominance of species in natural communities in a 1 year long field heating experiment and 6 year long field survey of natural populations. Finally, at a global spatial scale, we found the same relationship between relative abundance of species and frequency of extreme temperatures. Together, our results indicate that changes in frequency and amplitude of extreme high temperatures can alter the temporal and spatial structure of natural communities, and that these changes are driven by asymmetric effects of high temperatures on the demographic rates and fitness of species. They also highlight the importance of understanding how extreme events affect the life-history of species for predicting the impacts of climate change at the individual and community level, and emphasize the importance of using a broad range of approaches when studying climate change.
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Affiliation(s)
- Gang Ma
- Climate Change Biology Research Group, State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No 2, Yuanmingyuan West Road, Haidian District, Beijing, 100193, China
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30
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Seabloom EW, Borer ET, Gross K, Kendig AE, Lacroix C, Mitchell CE, Mordecai EA, Power AG. The community ecology of pathogens: coinfection, coexistence and community composition. Ecol Lett 2015; 18:401-15. [PMID: 25728488 DOI: 10.1111/ele.12418] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 09/20/2014] [Accepted: 01/14/2015] [Indexed: 12/11/2022]
Abstract
Disease and community ecology share conceptual and theoretical lineages, and there has been a resurgence of interest in strengthening links between these fields. Building on recent syntheses focused on the effects of host community composition on single pathogen systems, we examine pathogen (microparasite) communities using a stochastic metacommunity model as a starting point to bridge community and disease ecology perspectives. Such models incorporate the effects of core community processes, such as ecological drift, selection and dispersal, but have not been extended to incorporate host-pathogen interactions, such as immunosuppression or synergistic mortality, that are central to disease ecology. We use a two-pathogen susceptible-infected (SI) model to fill these gaps in the metacommunity approach; however, SI models can be intractable for examining species-diverse, spatially structured systems. By placing disease into a framework developed for community ecology, our synthesis highlights areas ripe for progress, including a theoretical framework that incorporates host dynamics, spatial structuring and evolutionary processes, as well as the data needed to test the predictions of such a model. Our synthesis points the way for this framework and demonstrates that a deeper understanding of pathogen community dynamics will emerge from approaches working at the interface of disease and community ecology.
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Affiliation(s)
- Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN, USA
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31
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Gray S, Cilia M, Ghanim M. Circulative, "nonpropagative" virus transmission: an orchestra of virus-, insect-, and plant-derived instruments. Adv Virus Res 2014; 89:141-99. [PMID: 24751196 DOI: 10.1016/b978-0-12-800172-1.00004-5] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Species of plant viruses within the Luteoviridae, Geminiviridae, and Nanoviridae are transmitted by phloem-feeding insects in a circulative, nonpropagative manner. The precise route of virus movement through the vector can differ across and within virus families, but these viruses all share many biological, biochemical, and ecological features. All share temporal and spatial constraints with respect to transmission efficiency. The viruses also induce physiological changes in their plant hosts resulting in behavioral changes in the insects that optimize the transmission of virus to new hosts. Virus proteins interact with insect, endosymbiont, and plant proteins to orchestrate, directly and indirectly, virus movement in insects and plants to facilitate transmission. Knowledge of these complex interactions allows for the development of new tools to reduce or prevent transmission, to quickly identify important vector populations, and to improve the management of these economically important viruses affecting agricultural and natural plant populations.
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Affiliation(s)
- Stewart Gray
- Biological Integrated Pest Management Research Unit, USDA, ARS, Ithaca, New York, USA; Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, USA.
| | - Michelle Cilia
- Biological Integrated Pest Management Research Unit, USDA, ARS, Ithaca, New York, USA; Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, USA; Boyce Thompson Institute for Plant Research, Ithaca, New York, USA
| | - Murad Ghanim
- Department of Entomology, Volcani Center, Bet Dagan, Israel
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32
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Borer ET, Kinkel LL, May G, Seabloom EW. The world within: Quantifying the determinants and outcomes of a host's microbiome. Basic Appl Ecol 2013. [DOI: 10.1016/j.baae.2013.08.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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33
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Salvaudon L, De Moraes CM, Mescher MC. Outcomes of co-infection by two potyviruses: implications for the evolution of manipulative strategies. Proc Biol Sci 2013; 280:20122959. [PMID: 23407835 PMCID: PMC3574378 DOI: 10.1098/rspb.2012.2959] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 01/22/2013] [Indexed: 12/12/2022] Open
Abstract
Recent studies have documented effects of plant viruses on host plants that appear to enhance transmission by insect vectors. But, almost no empirical work has explored the implications of such apparent manipulation for interactions among co-infecting pathogens. We examined single and mixed infections of two potyviruses, watermelon mosaic virus (WMV) and zucchini yellow mosaic virus (ZYMV), that frequently co-occur in cucurbitaceae populations and share the same aphid vectors. We found that ZYMV isolates replicated at similar rates in single and mixed infections, whereas WMV strains accumulated to significantly lower levels in the presence of ZYMV. Furthermore, ZYMV induced changes in leaf colour and volatile emissions that enhanced aphid (Aphis gossypii) recruitment to infected plants. By contrast, WMV did not elicit strong effects on plant-aphid interactions. Nevertheless, WMV was still readily transmitted from mixed infections, despite fairing poorly in in-plant competition. These findings suggest that pathogen effects on host-vector interactions may well influence competition among co-infecting pathogens. For example, if non-manipulative pathogens benefit from the increased vector traffic elicited by manipulative competitors, their costs of competition may be mitigated to some extent. Conversely, the benefits of manipulation may be limited by free-rider effects in systems where there is strong competition among pathogens for host resources and/or access to vectors.
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Affiliation(s)
- Lucie Salvaudon
- Department of Entomology, The Pennsylvania State University, University Park, PA16802, USA
- Laboratoire Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay F-91405, France
| | - Consuelo M. De Moraes
- Department of Entomology, The Pennsylvania State University, University Park, PA16802, USA
| | - Mark C. Mescher
- Department of Entomology, The Pennsylvania State University, University Park, PA16802, USA
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34
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Seabloom EW, Borer ET, Lacroix C, Mitchell CE, Power AG. Richness and composition of niche-assembled viral pathogen communities. PLoS One 2013; 8:e55675. [PMID: 23468848 PMCID: PMC3582609 DOI: 10.1371/journal.pone.0055675] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 01/02/2013] [Indexed: 01/20/2023] Open
Abstract
The pathogen and parasite community that inhabits every free-living organism can control host vital rates including lifespan and reproductive output. To date, however, there have been few experiments examining pathogen community assembly replicated at large-enough spatial scales to inform our understanding of pathogen dynamics in natural systems. Pathogen community assembly may be driven by neutral stochastic colonization and extinction events or by niche differentiation that constrains pathogen distributions to particular environmental conditions, hosts, or vectors. Here, we present results from a regionally-replicated experiment investigating the community of barley and cereal yellow dwarf viruses (B/CYDV's) in over 5000 experimentally planted individuals of six grass species along a 700 km latitudinal gradient along the Pacific coast of North America (USA) in response to experimentally manipulated nitrogen and phosphorus supplies. The composition of the virus community varied predictably among hosts and across nutrient-addition treatments, indicating niche differentiation among virus species. There were some concordant responses among the viral species. For example, the prevalence of most viral species increased consistently with perennial grass cover, leading to a 60% increase in the richness of the viral community within individual hosts (i.e., coinfection) in perennial-dominated plots. Furthermore, infection rates of the six host species in the field were highly correlated with vector preferences assessed in laboratory trials. Our results reveal the importance of niche differentiation in structuring virus assemblages. Virus species distributions reflected a combination of local host community composition, host species-specific vector preferences, and virus responses to host nutrition. In addition, our results suggest that heterogeneity among host species in their capacity to attract vectors or support pathogens between growing seasons can lead to positive covariation among virus species.
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Affiliation(s)
- Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota, USA.
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35
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Zhan J, McDonald BA. Experimental measures of pathogen competition and relative fitness. ANNUAL REVIEW OF PHYTOPATHOLOGY 2013; 51:131-53. [PMID: 23767846 DOI: 10.1146/annurev-phyto-082712-102302] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Competition among pathogen strains for limited host resources can have a profound effect on pathogen evolution. A better understanding of the principles and consequences of competition can be useful in designing more sustainable disease management strategies. The competitive ability and relative fitness of a pathogen strain are determined by its intrinsic biological properties, the resistance and heterogeneity of the corresponding host population, the population density and genetic relatedness of the competing strains, and the physical environment. Competitive ability can be inferred indirectly from fitness components, such as basic reproduction rate or transmission rate. However, pathogen strains that exhibit higher fitness components when they infect a host alone may not exhibit a competitive advantage when they co-infect the same host. The most comprehensive measures of competitive ability and relative fitness come from calculating selection coefficients in a mixed infection in a field setting. Mark-release-recapture experiments can be used to estimate fitness costs associated with unnecessary virulence and fungicide resistance.
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Affiliation(s)
- Jiasui Zhan
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
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36
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The community ecology of barley/cereal yellow dwarf viruses in Western US grasslands. Virus Res 2011; 159:95-100. [DOI: 10.1016/j.virusres.2011.05.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 05/13/2011] [Indexed: 11/22/2022]
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Moore SM, Manore CA, Bokil VA, Borer ET, Hosseini PR. Spatiotemporal model of barley and cereal yellow dwarf virus transmission dynamics with seasonality and plant competition. Bull Math Biol 2011; 73:2707-30. [PMID: 21505932 DOI: 10.1007/s11538-011-9654-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 03/24/2011] [Indexed: 11/29/2022]
Abstract
Many generalist pathogens are influenced by the spatial distributions and relative abundances of susceptible host species. The spatial structure of host populations can influence patterns of infection incidence (or disease outbreaks), and the effects of a generalist pathogen on host community dynamics in a spatially heterogeneous community may differ from predictions derived via simple models. In this paper, we model the transmission of a generalist pathogen within a patch framework that incorporates the movement of vectors between discrete host patches to investigate the effects of local host community composition and vector movement rates on disease dynamics.We use barley and cereal yellow dwarf viruses (B/CYDV), a suite of generalist, aphid-vectored pathogens of grasses, and their interactions with a range of host species as our case study. We examine whether B/CYDV can persist locally or in a patch framework across a range of host community configurations. We then determine how pathogen-mediated interactions between perennial and annual competitors are altered at the local and regional scale when the host populations are spatially structured. We find that the spatial configuration of the patch system, host composition within patches, and patch connectivity affect not only the ability of the pathogen to invade a fragmented system, but also determine whether the pathogen facilitates the invasion of a non-native host species. Further, our results suggest that connectivity can interact with arrival time and host infection tolerance to determine the success or failure of establishment for newly arriving species.
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Affiliation(s)
- S M Moore
- Department of Zoology, Oregon State University, Corvallis, OR 97331, USA.
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38
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Cronin JP, Welsh ME, Dekkers MG, Abercrombie ST, Mitchell CE. Host physiological phenotype explains pathogen reservoir potential. Ecol Lett 2011; 13:1221-32. [PMID: 20618842 DOI: 10.1111/j.1461-0248.2010.01513.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Control of emerging infectious diseases often hinges on identifying a pathogen reservoir, the source of disease transmission. The potential to function as a pathogen reservoir can be influenced by host lifespan, geographic provenance and phylogeny. Yet, no study has identified factors that causally determine the reservoir potential of diverse host species. We propose the host physiological phenotype hypothesis, which predicts that hosts with short-lived, poorly defended, nutrient rich and high metabolism tissue have greater values for three epidemiological parameters that determine reservoir potential: host susceptibility to infection, competence to infect vectors and ability to support vector populations. We experimentally tested these predictions using a generalist vectored virus and six wild grass species. Host physiological phenotype explained why hosts differed in all three epidemiological parameters while host lifespan, provenance and phylogeny could not explain host competence. Thus, a single, general axis describing variation in host physiological phenotype may explain reservoir potential.
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Affiliation(s)
- James Patrick Cronin
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
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39
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40
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Gibson LR, Li B, Remold SK. Treating cofactors can reverse the expansion of a primary disease epidemic. BMC Infect Dis 2010; 10:248. [PMID: 20731862 PMCID: PMC2940901 DOI: 10.1186/1471-2334-10-248] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 08/23/2010] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Cofactors, "nuisance" conditions or pathogens that affect the spread of a primary disease, are likely to be the norm rather than the exception in disease dynamics. Here we present a "simplest possible" demographic model that incorporates two distinct effects of cofactors: that on the transmission of the primary disease from an infected host bearing the cofactor, and that on the acquisition of the primary disease by an individual that is not infected with the primary disease but carries the cofactor. METHODS We constructed and analyzed a four-patch compartment model that accommodates a cofactor. We applied the model to HIV spread in the presence of the causal agent of genital schistosomiasis, Schistosoma hematobium, a pathogen commonly co-occurring with HIV in sub-Saharan Africa. RESULTS We found that cofactors can have a range of effects on primary disease dynamics, including shifting the primary disease from non-endemic to endemic, increasing the prevalence of the primary disease, and reversing demographic growth when the host population bears only the primary disease to demographic decline. We show that under parameter values based on the biology of the HIV/S. haematobium system, reduction of the schistosome-bearing subpopulations (e.g. through periodic use of antihelminths) can slow and even reverse the spread of HIV through the host population. CONCLUSIONS Typical single-disease models provide estimates of future conditions and guidance for direct intervention efforts relating only to the modeled primary disease. Our results suggest that, in circumstances under which a cofactor affects the disease dynamics, the most effective intervention effort might not be one focused on direct treatment of the primary disease alone. The cofactor model presented here can be used to estimate the impact of the cofactor in a particular disease/cofactor system without requiring the development of a more complicated model which incorporates many other specific aspects of the chosen disease/cofactor pair. Simulation results for the HIV/S. haematobium system have profound implications for disease management in developing areas, in that they provide evidence that in some cases treating cofactors may be the most successful and cost-effective way to slow the spread of primary diseases.
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Affiliation(s)
- Lee R Gibson
- Department of Mathematics, 328 Natural Sciences Bldg., University of Louisville, Louisville, KY 40292 USA
| | - Bingtuan Li
- Department of Mathematics, 328 Natural Sciences Bldg., University of Louisville, Louisville, KY 40292 USA
| | - Susanna K Remold
- Department of Biology, 139 Life Sciences Bldg., University of Louisville, Louisville, KY 40292 USA
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41
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Seabloom EW, Borer ET, Mitchell CE, Power AG. Viral diversity and prevalence gradients in North American Pacific Coast grasslands. Ecology 2010; 91:721-32. [PMID: 20426331 DOI: 10.1890/08-2170.1] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Host-pathogen interactions may be governed by the number of pathogens coexisting within an individual host (i.e., coinfection) and among different hosts, although most sampling in natural systems focuses on the prevalence of single pathogens and/or single hosts. We measured the prevalence of four barley and cereal yellow dwarf viruses (B/CYDVs) in three grass species at 26 natural grasslands along a 2000-km latitudinal gradient in the western United States and Canada. B/CYDVs are aphid-vectored RNA viruses that cause one of the most prevalent of all plant diseases worldwide. Pathogen prevalence and coinfection were uncorrelated, suggesting that different forces likely drive them. Coinfection, the number of viruses in a single infected host (alpha diversity), did not differ among host species but increased roughly twofold across our latitudinal transect. This increase in coinfection corresponded with a decline in among-host pathogen turnover (beta diversity), suggesting that B/CYDVs in northern populations experience less transmission limitation than in southern populations. In contrast to pathogen diversity, pathogen prevalence was a function of host identity as well as biotic and abiotic environmental conditions. Prevalence declined with precipitation and increased with soil nitrate concentration, an important limiting nutrient for hosts and vectors of B/CYDVs. This work demonstrates the need for further studies of processes governing coinfection, and the utility of applying theory developed to explain diversity in communities of free-living organisms to pathogen systems.
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Affiliation(s)
- Eric W Seabloom
- Oregon State University, Department of Zoology, 3029 Cordley Hall, Corvallis, Oregon 97330, USA.
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42
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Barrett LG, Kniskern JM, Bodenhausen N, Zhang W, Bergelson J. Continua of specificity and virulence in plant host-pathogen interactions: causes and consequences. THE NEW PHYTOLOGIST 2009; 183:513-529. [PMID: 19563451 DOI: 10.1111/j.1469-8137.2009.02927.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Ecological, evolutionary and molecular models of interactions between plant hosts and microbial pathogens are largely based around a concept of tightly coupled interactions between species pairs. However, highly pathogenic and obligate associations between host and pathogen species represent only a fraction of the diversity encountered in natural and managed systems. Instead, many pathogens can infect a wide range of hosts, and most hosts are exposed to more than one pathogen species, often simultaneously. Furthermore, outcomes of pathogen infection vary widely because host plants vary in resistance and tolerance to infection, while pathogens are also variable in their ability to grow on or within hosts. Environmental heterogeneity further increases the potential for variation in plant host-pathogen interactions by influencing the degree and fitness consequences of infection. Here, we describe these continua of specificity and virulence inherent within plant host-pathogen interactions. Using this framework, we describe and contrast the genetic and environmental mechanisms that underlie this variation, outline consequences for epidemiology and community structure, explore likely ecological and evolutionary drivers, and highlight several key areas for future research.
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Affiliation(s)
- Luke G Barrett
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
| | - Joel M Kniskern
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
| | - Natacha Bodenhausen
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
| | - Wen Zhang
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
| | - Joy Bergelson
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
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