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Plotnikova LY, Knaub VV. Exploitation of the genetic potential of Thinopyrum and Agropyron genera to protect wheat from diseases and environmental stresses. Vavilovskii Zhurnal Genet Selektsii 2024; 28:536-553. [PMID: 39280845 PMCID: PMC11393651 DOI: 10.18699/vjgb-24-60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/22/2024] [Accepted: 03/26/2024] [Indexed: 09/18/2024] Open
Abstract
Common wheat is one of the most important food crops in the world. Grain harvests can be increased by reducing losses from diseases and environmental stresses. The tertiary gene pool, including Thinopyrum spp., is a valuable resource for increasing genetic diversity and wheat resistance to fungal diseases and abiotic stresses. Distant hybridization between wheat and Thinopyrum spp. began in the 1920s in Russia, and later continued in different countries. The main results were obtained using the species Th. ponticum and Th. intermedium. Additionally, introgression material was created based on Th. elongatum, Th. bessarabicum, Th. junceiforme, Agropyron cristatum. The results of introgression for resistance to diseases (leaf, stem, and stripe rusts; powdery mildew; Fusarium head blight; and Septoria blotch) and abiotic stresses (drought, extreme temperatures, and salinity) to wheat was reviewed. Approaches to improving the agronomic properties of introgression breeding material (the use of irradiation, ph-mutants and compensating Robertsonian translocations) were described. The experience of long-term use in the world of a number of genes from the tertiary gene pool in protecting wheat from leaf and stem rust was observed. Th. ponticum is a nonhost for Puccinia triticina (Ptr) and P. graminis f. sp. tritici (Pgt) and suppresses the development of rust fungi on the plant surface. Wheat samples with the tall wheatgrass genes Lr19, Lr38, Sr24, Sr25 and Sr26 showed defence mechanisms similar to nonhosts resistance. Their influence led to disruption of the development of surface infection structures and fungal death when trying to penetrate the stomata (prehaustorial resistance or stomatal immunity). Obviously, a change in the chemical properties of fungal surface structures of races virulent to Lr19, Lr24, Sr24, Sr25, and Sr26 leads to a decrease in their adaptability to the environment. This possibly determined the durable resistance of cultivars to leaf and stem rusts in different regions. Alien genes with a similar effect are of interest for breeding cultivars with durable resistance to rust diseases and engineering crops with the help of molecular technologies.
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Affiliation(s)
- L Ya Plotnikova
- Omsk State Agrarian University named after P.A. Stolypin, Omsk, Russia
| | - V V Knaub
- Omsk State Agrarian University named after P.A. Stolypin, Omsk, Russia
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Krone MJ, Dong Y, Mideros SX. Effect of Quantitative Wheat Resistance on the Aggressiveness of Fusarium graminearum. PHYTOPATHOLOGY 2024; 114:1577-1586. [PMID: 38669176 DOI: 10.1094/phyto-06-23-0206-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Little is known about the selection pressures acting on plant pathogen populations, especially those applied by quantitative forms of resistance. Fusarium graminearum causes Fusarium head blight in wheat, producing significant yield losses and mycotoxin contamination. Quantitative host resistance is the best method to control Fusarium head blight. However, there needs to be more understanding of how disease resistance affects the evolution of plant pathogens. The aim of this study was to determine if the presence or absence of wheat resistance influenced the fitness components and genomic regions of F. graminearum. Thirty-one isolates from highly susceptible and 25 isolates from moderately resistant wheat lines were used. Isolate aggressiveness was measured by the area under the disease progress curve, visually damaged kernels, and deoxynivalenol contamination. The in vitro growth rate and spore production were also measured. Two whole-genome scans for selection were conducted with 333,297 single-nucleotide polymorphisms. One scan looked for signatures of selection in the entire sample, and the other scan was for divergent selection between the isolates from moderately resistant wheat and highly susceptible wheat. The subsample of isolates from highly susceptible wheat was primarily aggressive. Several regions of the F. graminearum genome with signatures for selection were identified. The moderately resistant wheat varieties used in this study did not select more aggressive isolates, suggesting that quantitative resistance is a durable method to control Fusarium head blight.
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Affiliation(s)
- Mara J Krone
- Department of Crop Sciences, University of Illinois, Urbana-Champaign, IL 61801
| | - Yanhong Dong
- Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108
| | - Santiago X Mideros
- Department of Crop Sciences, University of Illinois, Urbana-Champaign, IL 61801
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Cuevas-Zuviria B, Fraile A, García-Arenal F. An Agent-Based Model Shows How Mixed Infections Drive Multiyear Pathotype Dynamics in a Plant-Virus System. PHYTOPATHOLOGY 2024; 114:1276-1288. [PMID: 38330173 DOI: 10.1094/phyto-06-23-0214-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Mathematical models are widely used to understand the evolution and epidemiology of plant pathogens under a variety of scenarios. Here, we used this approach to analyze the effects of different traits intrinsic and extrinsic to plant-virus interactions on the dynamics of virus pathotypes in genetically heterogeneous plant-virus systems. For this, we propose an agent-based epidemiological model that includes epidemiologically significant pathogen life-history traits related to virulence, transmission, and survival in the environment and allows for integrating long- and short-distance transmission, primary and secondary infections, and within-host pathogen competition in mixed infections. The study focuses on the tobamovirus-pepper pathosystem. Model simulations allowed us to integrate pleiotropic effects of resistance-breaking mutations on different virus life-history traits into the net costs of resistance breaking, allowing for predictions on multiyear pathotype dynamics. We also explored the effects of two control measures, the use of host resistance and roguing of symptomatic plants, that modify epidemiological attributes of the pathogens to understand how their populations will respond to evolutionary pressures. One major conclusion points to the importance of pathogen competition within mixed-infected hosts as a component of the overall fitness of each pathogen that, thus, drives their multiyear dynamics.
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Affiliation(s)
- Bruno Cuevas-Zuviria
- Centro de Biotecnología y Genómica de Plantas (CBGP UPM-INIA/CSIC), Universidad Politécnica de Madrid (UPM) and E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas (CBGP UPM-INIA/CSIC), Universidad Politécnica de Madrid (UPM) and E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas (CBGP UPM-INIA/CSIC), Universidad Politécnica de Madrid (UPM) and E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Campus de Montegancedo, UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
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Wei S, Liu L, Chen G, Yang H, Huang L, Gong G, Luo P, Zhang M. Molecular evolution and phylogeographic analysis of wheat dwarf virus. Front Microbiol 2024; 15:1314526. [PMID: 38419641 PMCID: PMC10901289 DOI: 10.3389/fmicb.2024.1314526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/23/2024] [Indexed: 03/02/2024] Open
Abstract
Wheat dwarf virus (WDV) has caused considerable economic loss in the global production of grain crops. Knowledge of the evolutionary biology and population history of the pathogen remain poorly understood. We performed molecular evolution and worldwide phylodynamic analyses of the virus based on the genes in the protein-coding region of the entire viral genome. Our results showed that host-driven and geography-driven adaptation are major factors that affects the evolution of WDV. Bayesian phylogenetic analysis estimates that the average WDV substitution rate was 4.240 × 10-4 substitutions/site/year (95% credibility interval, 2.828 × 10-4-5.723 × 10-4), and the evolutionary rates of genes encoding proteins with virion-sense transcripts and genes encoding proteins with complementary-sense transcripts were different. The positively selected sites were detected in only two genes encoding proteins with complementary-sense, and WDV-barley are subject to stronger purifying selection than WDV-wheat. The time since the most recent common WDV ancestor was 1746 (95% credibility interval, 1517-1893) CE. Further analyses identified that the WDV-barley population and WDV-wheat population experienced dramatic expansion-decline episodes, and the expansion time of the WDV-barley population was earlier than that of the WDV-wheat population. Our phylogeographic analysis showed that the WDV population originating in Iran was subsequently introduced to Europe, and then spread from Eastern Europe to China.
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Affiliation(s)
- Shiqing Wei
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Linwen Liu
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Guoliang Chen
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Hui Yang
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Liang Huang
- State Key Laboratory for the Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Guoshu Gong
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - PeiGao Luo
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
| | - Min Zhang
- College of Agronomy, Sichuan Agricultural University, Chengdu, China
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Kang J, Yoon HM, Jung J, Yu S, Choi SY, Bae HW, Cho YH, Chung EH, Lee Y. Pleiotropic effects of N-acylhomoserine lactone synthase ExpI on virulence, competition, and transmission in Pectobacterium carotovorum subsp. carotovorum Pcc21. PEST MANAGEMENT SCIENCE 2024; 80:687-697. [PMID: 37758685 DOI: 10.1002/ps.7797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/18/2023] [Accepted: 09/28/2023] [Indexed: 09/29/2023]
Abstract
BACKGROUND Pectobacterium species are necrotrophic phytopathogenic bacteria that cause soft rot disease in economically important crops. The successful infection of host plants relies on interactions among virulence factors, competition, and transmission within hosts. Pectobacteria primarily produce and secrete plant cell-wall degrading enzymes (PCWDEs) for virulence. The regulation of PCWDEs is controlled by quorum sensing (QS). Thus, the QS system is crucial for disease development in pectobacteria through PCWDEs. RESULTS In this study, we identified a Tn-insertion mutant, M2, in the expI gene from a transposon mutant library of P. carotovorum subsp. carotovorum Pcc21 (hereafter Pcc21). The mutant exhibited reduced production and secretion of PCWDEs, impaired flagellar motility, and increased sensitivity to hydrogen peroxide, resulting in attenuated soft rot symptoms in cabbage and potato tubers. Transcriptomic analysis revealed the down-regulation of genes involved in the production and secretion in the mutant, consistent with the observed phenotype. Furthermore, the Pcc21 wild-type transiently colonized in the gut of Drosophila melanogaster within 12 h after feeding, while the mutant compromised colonization phenotype. Interestingly, Pcc21 produces a bacteriocin, carocin D, to compete with other bacteria. The mutant exhibited up-regulation of carocin D-encoding genes (caroDK) and inhibited the growth of a closely related bacterium, P. wasabiae. CONCLUSION Our results demonstrated the significance of ExpI in the overall pathogenic lifestyle of Pcc21, including virulence, competition, and colonization in plant and insect hosts. These findings suggest that disease outcome is a result of complex interactions mediated by ExpI across multiple steps. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Jihee Kang
- Department of Food Science and Biotechnology, CHA University, Pocheon, Republic of Korea
| | - Hye Min Yoon
- Department of Food Science and Biotechnology, CHA University, Pocheon, Republic of Korea
| | - Jaejoon Jung
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Seonmi Yu
- Department of Food Science and Biotechnology, CHA University, Pocheon, Republic of Korea
| | - Shin-Yae Choi
- Department of Pharmacy, and Institutes of Pharmaceutical Sciences, CHA University, Seongnam, Republic of Korea
| | - Hee-Won Bae
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - You-Hee Cho
- Department of Pharmacy, and Institutes of Pharmaceutical Sciences, CHA University, Seongnam, Republic of Korea
| | - Eui-Hwan Chung
- Department of Plant Biotechnology, Korea University, Seoul, Republic of Korea
| | - Yunho Lee
- Department of Food Science and Biotechnology, CHA University, Pocheon, Republic of Korea
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Chen C, Keunecke H, Bemm F, Gyetvai G, Neu E, Kopisch‐Obuch FJ, McDonald BA, Stapley J. GWAS reveals a rapidly evolving candidate avirulence effector in the Cercospora leaf spot pathogen. MOLECULAR PLANT PATHOLOGY 2024; 25:e13407. [PMID: 38009399 PMCID: PMC10799204 DOI: 10.1111/mpp.13407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/09/2023] [Accepted: 11/09/2023] [Indexed: 11/28/2023]
Abstract
The major resistance gene BvCR4 recently bred into sugar beet hybrids provides a high level of resistance to Cercospora leaf spot caused by the fungal pathogen Cercospora beticola. The occurrence of pathogen strains that overcome BvCR4 was studied using field trials in Switzerland conducted under natural disease pressure. Virulence of a subset of these strains was evaluated in a field trial conducted under elevated artificial disease pressure. We created a new C. beticola reference genome and mapped whole genome sequences of 256 isolates collected in Switzerland and Germany. These were combined with virulence phenotypes to conduct three separate genome-wide association studies (GWAS) to identify candidate avirulence genes. We identified a locus associated with avirulence containing a putative avirulence effector gene named AvrCR4. All virulent isolates either lacked AvrCR4 or had nonsynonymous mutations within the gene. AvrCR4 was present in all 74 isolates from non-BvCR4 hybrids, whereas 33 of 89 isolates from BvCR4 hybrids carried a deletion. We also mapped genomic data from 190 publicly available US isolates to our new reference genome. The AvrCR4 deletion was found in only one of 95 unique isolates from non-BvCR4 hybrids in the United States. AvrCR4 presents a unique example of an avirulence effector in which virulent alleles have only recently emerged. Most likely these were selected out of standing genetic variation after deployment of BvCR4. Identification of AvrCR4 will enable real-time screening of C. beticola populations for the emergence and spread of virulent isolates.
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Affiliation(s)
- Chen Chen
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
| | | | | | | | - Enzo Neu
- KWS SAAT SE & Co. KGaAEinbeckGermany
| | | | - Bruce A. McDonald
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
| | - Jessica Stapley
- Plant Pathology GroupInstitute of Integrative Biology, ETH ZurichZürichSwitzerland
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Wei S, Chen G, Yang H, Huang L, Gong G, Luo P, Zhang M. Global molecular evolution and phylogeographic analysis of barley yellow dwarf virus based on the cp and mp genes. Virol J 2023; 20:130. [PMID: 37340422 DOI: 10.1186/s12985-023-02084-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 05/26/2023] [Indexed: 06/22/2023] Open
Abstract
Barley yellow dwarf virus (BYDV) has caused considerable losses in the global production of grain crops such as wheat, barley and maize. We investigated the phylodynamics of the virus by analysing 379 and 485 nucleotide sequences of the genes encoding the coat protein and movement protein, respectively. The maximum clade credibility tree indicated that BYDV-GAV and BYDV-MAV, BYDV-PAV and BYDV-PAS share the same evolutionary lineage, respectively. The diversification of BYDV arises from its adaptability to vector insects and geography. Bayesian phylogenetic analyses showed that the mean substitution rates of the coat and movement proteins of BYDV ranged from 8.327 × 10- 4 (4.700 × 10- 4-1.228 × 10- 3) and 8.671 × 10- 4 (6.143 × 10- 4-1.130 × 10- 3) substitutions/site/year, respectively. The time since the most recent common BYDV ancestor was 1434 (1040-1766) CE (Common Era). The Bayesian skyline plot (BSP) showed that the BYDV population experienced dramatic expansions approximately 8 years into the 21st century, followed by a dramatic decline in less than 15 years. Our phylogeographic analysis showed that the BYDV population originating in the United States was subsequently introduced to Europe, South America, Australia and Asia. The migration pathways of BYDV suggest that the global spread of BYDV is associated with human activities.
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Affiliation(s)
- Shiqing Wei
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Guoliang Chen
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Hui Yang
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Liang Huang
- State Key Laboratory for the Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Guoshu Gong
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - PeiGao Luo
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China
| | - Min Zhang
- College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China.
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Lo ML, Thanh TAV, Midot F, Lau SYL, Wong WC, Tung HJ, Jee MS, Chin MY, Melling L. Comparison of Ganoderma boninense Isolate's Aggressiveness Using Infected Oil Palm Seedlings. J Microbiol 2023; 61:449-459. [PMID: 37097587 PMCID: PMC10167175 DOI: 10.1007/s12275-023-00040-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/06/2023] [Accepted: 03/09/2023] [Indexed: 04/26/2023]
Abstract
Basal stem rot incidence caused by a white-rot fungus, Ganoderma boninense, is the major disease of oil palm in Southeast Asia. The rate of disease transmission and host damage are affected by variations in pathogen aggressiveness. Several other studies have used the disease severity index (DSI) to determine G. boninense aggressiveness levels while verifying disease using a culture-based method, which might not provide accurate results or be feasible in all cases. To differentiate G. boninense aggressiveness, we employed the DSI and vegetative growth measurement of infected oil palm seedlings. Disease confirmation was performed through scanning electron microscopy and molecular identification of fungal DNA from both infected tissue and fungi isolated from Ganoderma selective medium. Two-month-old oil palm seedlings were artificially inoculated with G. boninense isolates (2, 4A, 5A, 5B, and 7A) sampled from Miri (Lambir) and Mukah (Sungai Meris and Sungai Liuk), Sarawak. The isolates were categorized into three groups: highly aggressive (4A and 5B), moderately aggressive (5A and 7A), and less aggressive (2). Isolate 5B was identified as the most aggressive, and it was the only one to result in seedling mortality. Out of the five vegetative growth parameters measured, only the bole size between treatments was not affected. The integration of both conventional and molecular approaches in disease confirmation allows for precise detection.
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Affiliation(s)
- Mei Lieng Lo
- Sarawak Tropical Peat Research Institute, 94300, Kota Samarahan, Sarawak, Malaysia
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia
| | - Tu Anh Vu Thanh
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia
| | - Frazer Midot
- Sarawak Tropical Peat Research Institute, 94300, Kota Samarahan, Sarawak, Malaysia
| | - Sharon Yu Ling Lau
- Sarawak Tropical Peat Research Institute, 94300, Kota Samarahan, Sarawak, Malaysia.
| | - Wei Chee Wong
- Advanced Agriecological Research Sdn. Bhd., Kota Damansara, 47810, Petaling Jaya, Selangor, Malaysia
| | - Hun Jiat Tung
- Advanced Agriecological Research Sdn. Bhd., Kota Damansara, 47810, Petaling Jaya, Selangor, Malaysia
| | - Mui Sie Jee
- Sarawak Tropical Peat Research Institute, 94300, Kota Samarahan, Sarawak, Malaysia
| | - Mei-Yee Chin
- Sarawak Tropical Peat Research Institute, 94300, Kota Samarahan, Sarawak, Malaysia
| | - Lulie Melling
- Sarawak Tropical Peat Research Institute, 94300, Kota Samarahan, Sarawak, Malaysia
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Chen J, Gu C, Ruan Z, Tang M. Competition of SARS-CoV-2 variants on the pandemic transmission dynamics. CHAOS, SOLITONS, AND FRACTALS 2023; 169:113193. [PMID: 36817403 PMCID: PMC9915129 DOI: 10.1016/j.chaos.2023.113193] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/22/2023] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
SARS-CoV-2 has produced various variants during its ongoing evolution. The competitive behavior driven by the co-transmission of these variants has influenced the pandemic transmission dynamics. Therefore, studying the impact of competition between SARS-CoV-2 variants on pandemic transmission dynamics is of considerable practical importance. In order to formalize the mechanism of competition between SARS-CoV-2 variants, we propose an epidemic model that takes into account the co-transmission of competing variants. The model focuses on how cross-immunity influences the transmission dynamics of SARS-CoV-2 through competitive mechanisms between strains. We found that inter-strain competition affects not only both the final size and the replacement time of the variants, but also the invasive behavior of new variants in the future. Due to the limited extent of cross-immunity in previous populations, we predict that the new strain may infect the largest number of individuals in China without control interventions. Moreover, we also observed the possibility of periodic outbreaks in the same lineage and the possibility of the resurgence of previous lineages. Without the invasion of a new variant, the previous variant (Delta variant) is projected to resurgence as early as 2023. However, its resurgence may be prevented by a new variant with a greater competitive advantage.
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Affiliation(s)
- Jiaqi Chen
- Department of Systems Science, Business School, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Changgui Gu
- Department of Systems Science, Business School, University of Shanghai for Science and Technology, Shanghai, 200093, China
| | - Zhongyuan Ruan
- Institute of Cyberspace Security, Zhejiang University of Technology, Hangzhou, 310023, China
| | - Ming Tang
- School of Physics and Electronic Science, East China Normal University, Shanghai, 200241, China
- Shanghai Key Laboratory of Multidimensional Information Processing, East China Normal University, Shanghai, 200241, China
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The Hydrophobin Gene Family Confers a Fitness Trade-off between Spore Dispersal and Host Colonization in Penicillium expansum. mBio 2022; 13:e0275422. [PMID: 36374077 PMCID: PMC9765440 DOI: 10.1128/mbio.02754-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Hydrophobins are small amphipathic surface proteins found exclusively in fungi. In filamentous ascomycetes, one conserved role of a subset of hydrophobins is their requirement for spore dispersal. Other contributions of these proteins to fungal biology are less clear and vary across genera. To determine the functions of hydrophobins in the biology and virulence of this fungus, we created seven single mutants and a septuple-deletion mutant (Δsep) of the entire putative P. expansum hydrophobin gene family. One spore hydrophobin, HfbA, shared 72.56% sequence identity to the Aspergillus fumigatus spore hydrophobin RodA and was required for efficient spore dispersion in P. expansum. The Δsep mutant was likewise reduced in spore dispersal, hypothesized to be due to the aberrant shape and clumping of the Δsep conidia and conidiophores. Additionally, the Δsep mutant presented several differences in physiological traits, including decreased survival in extreme cold temperatures and increased production of several toxic secondary metabolites. Most striking was the unexpected fitness advantage that the Δsep strain displayed in competitive passaging with the wild-type strain on host apple where the mutant significantly increased in percentage of the colonizing population. This work uncovers potential ecological trade-offs of hydrophobin presence in filamentous fungi. IMPORTANCE Hydrophobins are amphipathic secreted proteins uniquely found in filamentous fungi. These proteins self-assemble and constitute the outer most layer of fungal surfaces thus mediating multiple aspects of fungal interactions with their environments. Hydrophobins facilitate spore dispersal, yet a full understanding of the function and need for multiple hydrophobins in fungal species remains elusive. To address the role of this protein family in Penicillium expansum, the causative agent of blue mold disease in pome fruit, all seven putative hydrophobin genes were deleted and the mutant assessed for numerous physiological traits and virulence on fruit. Despite showing a decrease in spore dispersal, the septuple-deletion mutant was more fit than the wild type in competitive pathogenicity tests on apple. Our findings suggest this gene family illustrates a functional trade-off between dispersal and host colonization in P. expansum.
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Mouafo-Tchinda RA, Fall ML, Beaulieu C, Carisse O. Competition Between Plasmopara viticola Clade riparia and Clade aestivalis: A Race to Lead Grape Downy Mildew Epidemics. PLANT DISEASE 2022; 106:2866-2875. [PMID: 35536207 DOI: 10.1094/pdis-11-21-2465-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
There is evidence of five clades of Plasmopara viticola in the world. Only two clades, riparia and aestivalis, have been identified as responsible for downy mildew epidemics in Quebec, Canada. It was reported in 2021 that epidemics caused by clade riparia start 2 or 3 weeks before those caused by clade aestivalis and that clade aestivalis was more aggressive than clade riparia. The objective of this work was to study the competition between P. viticola clade riparia (A) and clade aestivalis (B) and to compare the aggressiveness of both clades in mono- and coinfection situations. Suspensions of sporangia from both clades with six percentage combinations (AB 100-0; AB 89-11; AB 74-26; AB 46-54; AB 23-77; and AB 0-100) were inoculated on leaf discs (cultivar Vidal), and three other combinations (AB 88-12; AB 68-32; and AB 47-53) were inoculated on living leaves of grape plants (cultivar Vidal). Then, sporangium production, expressed as the percentage of sporangia produced by each clade, was estimated on leaf discs after eight cycles of infection-sporulation and then validated on living grape leaves after five cycles. The aggressiveness of clades in monoinfection situations on leaf discs was compared with that in coinfection situations. The results show that the percentage of sporangia produced by clade aestivalis increases with the infection-sporulation cycle while that produced by clade riparia decreases. The area under the sporangium production progress curve (AUSPPC) of clade aestivalis was significantly higher than that of clade riparia. The aggressiveness of P. viticola clades riparia and aestivalis in coinfection situations was different from that in monoinfection situations and was strongly influenced by the percentage of each clade in competition. These results suggest that, on the grapevine cultivar Vidal, P. viticola clade aestivalis is more competitive than clade riparia and that the percentage of each clade present in the vineyard should be considered for management of downy mildew.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Romaric A Mouafo-Tchinda
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, 2500 de l'Université Boulevard, Sherbrooke, QC, J1K 2R1, Canada
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC, J3B 3E6, Canada
| | - Mamadou L Fall
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC, J3B 3E6, Canada
| | - Carole Beaulieu
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, 2500 de l'Université Boulevard, Sherbrooke, QC, J1K 2R1, Canada
| | - Odile Carisse
- Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC, J3B 3E6, Canada
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12
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Sun B, Zhu G, Xie X, Chai A, Li L, Shi Y, Li B. Double Mutations in Succinate Dehydrogenase Are Involved in SDHI Resistance in Corynespora cassiicola. Microorganisms 2022; 10:microorganisms10010132. [PMID: 35056581 PMCID: PMC8779870 DOI: 10.3390/microorganisms10010132] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 12/31/2021] [Accepted: 01/04/2022] [Indexed: 02/05/2023] Open
Abstract
Simple Summary With the application of fungicide in agriculture, resistance to fungicide has become a serious problem. It is important to assess the evolution of resistance for development of disease prevention and control. We confirmed, by site-directed mutagenesis, that single mutations conferring moderate or low resistance are more likely to evolve into double mutations conferring higher resistance under the selective pressure of SDHI. However, the double mutations suffer large of fitness penalty than single mutation. We recommend that the use of SDHI in agriculture should be appropriately reduced or that other types of fungicides should be used to control plant diseases, such as dicarboximide fungicides (DCFs), to avoid the emergence of very resistant plant pathogens. Abstract With the further application of succinate dehydrogenase inhibitors (SDHI), the resistance caused by double mutations in target gene is gradually becoming a serious problem, leading to a decrease of control efficacy. It is important to assess the sensitivity and fitness of double mutations to SDHI in Corynespora cassiicola and analysis the evolution of double mutations. We confirmed, by site-directed mutagenesis, that all double mutations (B-I280V+D-D95E/D-G109V/D-H105R, B-H278R+D-D95E/D-G109V, B-H278Y+D-D95E/D-G109V) conferred resistance to all SDHI and exhibited the increased resistance to at least one fungicide than single point mutation. Analyses of fitness showed that all double mutations had lower fitness than the wild type; most of double mutations suffered more fitness penalties than the corresponding single mutants. We also further found that double mutations (B-I280V+D-D95E/D-G109V/D-H105R) containing low SDHI-resistant single point mutation (B-I280V) exhibited higher resistance to SDHI and low fitness penalty than double mutations (B-H278Y+D-D95E/D-G109V) containing high SDHI-resistant single mutations (B-H278Y). Therefore, we may infer that a single mutation conferring low resistance is more likely to evolve into a double mutation conferring higher resistance under the selective pressure of SDHI. Taken together, our results provide some important reference for resistance management.
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13
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Eck JL, Barrès B, Soubeyrand S, Sirén J, Numminen E, Laine AL. Strain Diversity and Spatial Distribution Are Linked to Epidemic Dynamics in Host Populations. Am Nat 2022; 199:59-74. [DOI: 10.1086/717179] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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14
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Deka A, Bhattacharyya S. The effect of human vaccination behaviour on strain competition in an infectious disease: An imitation dynamic approach. Theor Popul Biol 2021; 143:62-76. [PMID: 34942233 DOI: 10.1016/j.tpb.2021.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/13/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022]
Abstract
Strain competition plays an important role in shaping the dynamics of multiple pathogen outbreaks in a population. Competition may lead to exclusion of some pathogens, while it may influence the invasion of an emerging mutant in the population. However, little emphasis has been given to understand the influence of human vaccination choice on pathogen competition or strain invasion for vaccine-preventable infectious diseases. Coupling game dynamic framework of vaccination choice and compartmental disease transmission model of two strains, we explore invasion and persistence of a mutant in the population despite having a lower reproduction rate than the resident one. We illustrate that higher perceived strain severity and lower perceived vaccine efficacy are necessary conditions for the persistence of a mutant strain. The numerical simulation also extends these invasion and persistence analyses under asymmetric cross-protective immunity of these strains. We show that the dynamics of this cross-immunity model under human vaccination choices is determined by the interplay of parameters defining the cross-immune response function, perceived risk of infection, and vaccine efficacy, and it can exhibit invasion and persistence of mutant strain, even complete exclusion of resident strain in the regime of sufficiently high perceived risk. We conclude by discussing public health implications of the results, that proper risk communication in public about the severity of the disease is an important task to reduce the chance of mutant invasion. Thus, understanding pathogen competitions under social interactions and choices may be an important component for policymakers for strategic decision-making.
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Affiliation(s)
- Aniruddha Deka
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, State College, 16802, PA, USA; Disease Modelling Laboratory, Department of Mathematics, Shiv Nadar University, Gautam Buddha Nagar, 201314, UP, India.
| | - Samit Bhattacharyya
- Disease Modelling Laboratory, Department of Mathematics, Shiv Nadar University, Gautam Buddha Nagar, 201314, UP, India.
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15
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Nuismer SL, C. Layman N, Redwood AJ, Chan B, Bull JJ. Methods for measuring the evolutionary stability of engineered genomes to improve their longevity. Synth Biol (Oxf) 2021; 6:ysab018. [PMID: 34712842 PMCID: PMC8546616 DOI: 10.1093/synbio/ysab018] [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: 02/19/2021] [Revised: 07/05/2021] [Accepted: 07/26/2021] [Indexed: 11/14/2022] Open
Abstract
Diverse applications rely on engineering microbes to carry and express foreign transgenes. This engineered baggage rarely benefits the microbe and is thus prone to rapid evolutionary loss when the microbe is propagated. For applications where a transgene must be maintained for extended periods of growth, slowing the rate of transgene evolution is critical and can be achieved by reducing either the rate of mutation or the strength of selection. Because the benefits realized by changing these quantities will not usually be equal, it is important to know which will yield the greatest improvement to the evolutionary half-life of the engineering. Here, we provide a method for jointly estimating the mutation rate of transgene loss and the strength of selection favoring these transgene-free, revertant individuals. The method requires data from serial transfer experiments in which the frequency of engineered genomes is monitored periodically. Simple mathematical models are developed that use these estimates to predict the half-life of the engineered transgene and provide quantitative predictions for how alterations to mutation and selection will influence longevity. The estimation method and predictive tools have been implemented as an interactive web application, MuSe.
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Affiliation(s)
- Scott L Nuismer
- Department of Biological Sciences, University of Idaho, 875 Perimeter Dr, Moscow, Idaho 83844, USA
- Department of Mathematics, University of Idaho, 875 Perimeter Dr, Moscow, Idaho 83844, USA
| | - Nathan C. Layman
- Department of Biological Sciences, University of Idaho, 875 Perimeter Dr, Moscow, Idaho 83844, USA
| | - Alec J Redwood
- School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, Australia
- The Institute for Respiratory Health, Nedlands, Western Australia, Australia
| | - Baca Chan
- School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, Australia
- The Institute for Respiratory Health, Nedlands, Western Australia, Australia
| | - James J Bull
- Department of Biological Sciences, University of Idaho, 875 Perimeter Dr, Moscow, Idaho 83844, USA
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16
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Wuest SE, Peter R, Niklaus PA. Ecological and evolutionary approaches to improving crop variety mixtures. Nat Ecol Evol 2021; 5:1068-1077. [PMID: 34211140 DOI: 10.1038/s41559-021-01497-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/28/2021] [Indexed: 02/06/2023]
Abstract
Variety mixtures can provide a range of benefits for both the crop and the environment. Their utility for the suppression of pathogens, especially in small grain crops, is well established and has seen some remarkable successes. However, despite decades of academic interest in the topic, commercial efforts to develop, release and promote variety mixtures remain peripheral to normal breeding activities. Here we argue that this is because simple but general design principles that allow for the optimization of multiple mixture benefits are currently lacking. We therefore review the practical and conceptual challenges inherent in the development of variety mixtures, and discuss common approaches to overcome these. We further consider three domains in which they might be particularly beneficial: pathogen resistance, yield stability and yield enhancement. We demonstrate that combining evolutionary and ecological concepts with data typically available from breeding and variety testing programmes could make mixture development easier and more economic. Identifying synergies between the breeding for monocultures and mixtures may even be key to the widespread adoption of mixtures-to the profit of breeders, farmers and society as a whole.
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Affiliation(s)
- Samuel E Wuest
- Group Breeding Research, Division Plant Breeding, Agroscope, Wädenswil, Switzerland.
| | - Roland Peter
- Division Plant Breeding, Agroscope, Zurich, Switzerland
| | - Pascal A Niklaus
- Department of Evolutionary Biology and Environmental Studies & Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
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17
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Karki HS, Jansky SH, Halterman DA. Screening of Wild Potatoes Identifies New Sources of Late Blight Resistance. PLANT DISEASE 2021; 105:368-376. [PMID: 32755364 DOI: 10.1094/pdis-06-20-1367-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Late blight (LB) of potato is considered one of the most devastating plant diseases in the world. Most cultivated potatoes are susceptible to this disease. However, wild relatives of potatoes are an excellent source of LB resistance. We screened 384 accessions of 72 different wild potato species available from the U.S. Potato GeneBank against the LB pathogen Phytophthora infestans in a detached leaf assay (DLA). P. infestans isolates US-23 and NL13316 were used in the DLA to screen the accessions. Although all plants in 273 accessions were susceptible, all screened plants in 39 accessions were resistant. Resistant and susceptible plants were found in 33 accessions. All tested plants showed a partial resistance phenotype in two accessions, segregation of resistant and partial resistant plants in nine accessions, segregation of partially resistant and susceptible plants in four accessions, and segregation of resistant, partially resistant, and susceptible individuals in 24 accessions. We found several species that were never before reported to be resistant to LB: Solanum albornozii, S. agrimoniifolium, S. chomatophilum, S. ehrenbergii, S. hypacrarthrum, S. iopetalum, S. palustre, S. piurae, S. morelliforme, S. neocardenasii, S. trifidum, and S. stipuloideum. These new species could provide novel sources of LB resistance. P. infestans clonal lineage-specific screening of selected species was conducted to identify the presence of RB resistance. We found LB resistant accessions in Solanum verrucosum, Solanum stoloniferum, and S. morelliforme that were susceptible to the RB overcoming isolate NL13316, indicating the presence of RB-like resistance in these species.
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Affiliation(s)
- Hari S Karki
- U.S. Department of Agriculture-Agricultural Research Service, Vegetable Crops Research Unit, Madison, WI 53706
| | - Shelly H Jansky
- U.S. Department of Agriculture-Agricultural Research Service, Vegetable Crops Research Unit, Madison, WI 53706
- Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706
| | - Dennis A Halterman
- U.S. Department of Agriculture-Agricultural Research Service, Vegetable Crops Research Unit, Madison, WI 53706
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18
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Blin P, Robic K, Khayi S, Cigna J, Munier E, Dewaegeneire P, Laurent A, Jaszczyszyn Y, Hong KW, Chan KG, Beury A, Reverchon S, Giraud T, Hélias V, Faure D. Pattern and causes of the establishment of the invasive bacterial potato pathogen Dickeya solani and of the maintenance of the resident pathogen D. dianthicola. Mol Ecol 2020; 30:608-624. [PMID: 33226678 DOI: 10.1111/mec.15751] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 11/09/2020] [Accepted: 11/18/2020] [Indexed: 11/29/2022]
Abstract
Invasive pathogens can be a threat when they affect human health, food production or ecosystem services, by displacing resident species, and we need to understand the cause of their establishment. We studied the patterns and causes of the establishment of the pathogen Dickeya solani that recently invaded potato agrosystems in Europe by assessing its invasion dynamics and its competitive ability against the closely related resident D. dianthicola species. Epidemiological records over one decade in France revealed the establishment of D. solani and the maintenance of the resident D. dianthicola in potato fields exhibiting blackleg symptoms. Using experimentations, we showed that D. dianthicola caused a higher symptom incidence on aerial parts of potato plants than D. solani, while D. solani was more aggressive on tubers (i.e. with more severe symptoms). In co-infection assays, D. dianthicola outcompeted D. solani in aerial parts, while the two species co-existed in tubers. A comparison of 76 D. solani genomes (56 of which have been sequenced here) revealed balanced frequencies of two previously uncharacterized alleles, VfmBPro and VfmBSer , at the vfmB virulence gene. Experimental inoculations showed that the VfmBSer population was more aggressive on tubers, while the VfmBPro population outcompeted the VfmBSer population in stem lesions, suggesting an important role of the vfmB virulence gene in the ecology of the pathogens. This study thus brings novel insights allowing a better understanding of the pattern and causes of the D.solani invasion into potato production agrosystems, and the reasons why the endemic D. dianthicola nevertheless persisted.
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Affiliation(s)
- Pauline Blin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, Gif-sur-Yvette, France
| | - Kévin Robic
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, Gif-sur-Yvette, France.,French Federation of Seed Potato Growers (FN3PT/inov3PT), Paris, France
| | - Slimane Khayi
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, Gif-sur-Yvette, France.,Biotechnology Research Unit, National Institute for Agronomic Research (INRA), Rabat, Morocco
| | - Jérémy Cigna
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, Gif-sur-Yvette, France.,French Federation of Seed Potato Growers (FN3PT/inov3PT), Paris, France
| | - Euphrasie Munier
- French Federation of Seed Potato Growers (FN3PT/inov3PT), Paris, France
| | | | - Angélique Laurent
- French Federation of Seed Potato Growers (FN3PT/inov3PT), Paris, France
| | - Yan Jaszczyszyn
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, Gif-sur-Yvette, France
| | - Kar-Wai Hong
- International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Kok-Gan Chan
- International Genome Centre, Jiangsu University, Zhenjiang, China.,Division of Genetics and Molecular Biology, Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Amélie Beury
- French Federation of Seed Potato Growers (FN3PT/inov3PT), Paris, France
| | - Sylvie Reverchon
- Microbiologie Adaptation et Pathogénie (MAP), UMR5240, CNRS, INSA-Lyon, Univ. Lyon, Université Claude Bernard, Lyon 1, Villeurbanne, France
| | - Tatiana Giraud
- Ecologie Systématique et Evolution, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Valérie Hélias
- French Federation of Seed Potato Growers (FN3PT/inov3PT), Paris, France
| | - Denis Faure
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, Gif-sur-Yvette, France
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19
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Facilitative priority effects drive parasite assembly under coinfection. Nat Ecol Evol 2020; 4:1510-1521. [PMID: 32868915 DOI: 10.1038/s41559-020-01289-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/22/2020] [Indexed: 12/14/2022]
Abstract
Host individuals are often coinfected with diverse parasite assemblages, resulting in complex interactions among parasites within hosts. Within hosts, priority effects occur when the infection sequence alters the outcome of interactions among parasites. Yet, the role of host immunity in this process remains poorly understood. We hypothesized that the host response to the first infection could generate priority effects among parasites, altering the assembly of later-arriving strains during epidemics. We tested this by infecting sentinel host genotypes of Plantago lanceolata with strains of the fungal parasite Podosphaera plantaginis and measuring susceptibility to subsequent infection during experimental and natural epidemics. In these experiments, prior infection by one strain often increased susceptibility to other strains, and these facilitative priority effects altered the structure of parasite assemblages, but this effect depended on host genotype, host population and parasite genotype. Thus, host genotype, spatial structure and priority effects among strains all independently altered parasite assembly. Using a fine-scale survey and sampling of infections on wild hosts in several populations, we then identified a signal of facilitative priority effects, which altered parasite assembly during natural epidemics. Together, these results provide evidence that within-host priority effects of early-arriving strains can drive parasite assembly, with implications for how strain diversity is spatially and temporally distributed during epidemics.
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20
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Précigout PA, Robert C, Claessen D. Adaptation of Biotrophic Leaf Pathogens to Fertilization-Mediated Changes in Plant Traits: A Comparison of the Optimization Principle to Invasion Fitness. PHYTOPATHOLOGY 2020; 110:1039-1048. [PMID: 31928514 DOI: 10.1094/phyto-08-19-0317-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
One of the conclusions of evolutionary ecology applied to agroecosystem management is that sustainable disease management strategies must be adaptive to overcome the immense adaptive potential of crop pathogens. In this context, knowledge of how pathogens adapt to changes in cultural practices is necessary. In this article we address the issue of the evolutionary response of biotrophic crop pathogens to changes in fertilization practices. For this purpose, we compare predictions of latent period evolution based on three empirical fitness measures (seasonal spore production, within-season exponential growth rate, and area under disease progress curves [AUDPCs]) with predictions based on the concept of invasion fitness from adaptive dynamics. We use pairwise invisibility plots to identify the evolutionarily stable strategies (ESSs) of the pathogen latent period. We find that the ESS latent period is in between the latent periods that maximize the seasonal spore production and the within-season exponential growth rate of the pathogen. The latent periods that maximize the AUDPC are similar to those of the ESS latent periods. The AUDPC may therefore be a critical variable to determine the issue of between-strain competition and shape pathogen evolution.
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Affiliation(s)
- Pierre-Antoine Précigout
- UMR EcoSys, INRAe-AgroParisTech, 78850 Thiverval-Grignon, France
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS-ENS-INSERM UMR8197, Ecole Normale Supérieure, 75005 Paris, France
| | - Corinne Robert
- UMR EcoSys, INRAe-AgroParisTech, 78850 Thiverval-Grignon, France
| | - David Claessen
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS-ENS-INSERM UMR8197, Ecole Normale Supérieure, 75005 Paris, France
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21
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Cowger C, Brown JKM. Durability of Quantitative Resistance in Crops: Greater Than We Know? ANNUAL REVIEW OF PHYTOPATHOLOGY 2019; 57:253-277. [PMID: 31206351 DOI: 10.1146/annurev-phyto-082718-100016] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Quantitative resistance (QR) to crop diseases has usually been much more durable than major-gene, effector-triggered resistance. It has been observed that the effectiveness of some QR has eroded as pathogens adapt to it, especially when deployment is extensive and epidemics occur regularly, but it generally declines more slowly than effector-triggered resistance. Changes in aggressiveness and specificity of diverse pathogens on cultivars with QR have been recorded, along with experimental data on fitness costs of pathogen adaptation to QR, but there is little information about molecular mechanisms of adaptation. Some QR has correlated or antagonistic effects on multiple diseases. Longitudinal data on cultivars' disease ratings in trials over several years can be used to assess the significance of QR for durable resistance in crops. It is argued that published data likely underreport the durability of QR, owing to publication bias. The implications of research on QR for plant breeding are discussed.
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Affiliation(s)
- Christina Cowger
- USDA-ARS and North Carolina State University, Raleigh, North Carolina 27695, USA;
| | - James K M Brown
- Department of Crop Genetics, John Innes Centre, Colney, Norwich NR4 7UK, United Kingdom;
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22
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Busby PE, Crutsinger G, Barbour M, Newcombe G. Contingency rules for pathogen competition and antagonism in a genetically based, plant defense hierarchy. Ecol Evol 2019; 9:6860-6868. [PMID: 31380021 PMCID: PMC6662256 DOI: 10.1002/ece3.5253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 03/29/2019] [Accepted: 04/06/2019] [Indexed: 01/19/2023] Open
Abstract
Plant defense against pathogens includes a range of mechanisms, including, but not limited to, genetic resistance, pathogen-antagonizing endophytes, and pathogen competitors. The relative importance of each mechanism can be expressed in a hierarchical view of defense. Several recent studies have shown that pathogen antagonism is inconsistently expressed within the plant defense hierarchy. Our hypothesis is that the hierarchy is governed by contingency rules that determine when and where antagonists reduce plant disease severity.Here, we investigated whether pathogen competition influences pathogen antagonism using Populus as a model system. In three independent field experiments, we asked whether competition for leaf mesophyll cells between a Melampsora rust pathogen and a microscopic, eriophyid mite affects rust pathogen antagonism by fungal leaf endophytes. The rust pathogen has an annual, phenological disadvantage in competition with the mite because the rust pathogen must infect its secondary host in spring before infecting Populus. We varied mite-rust competition by utilizing Populus genotypes characterized by differential genetic resistance to the two organisms. We inoculated plants with endophytes and allowed mites and rust to infect plants naturally.Two contingency rules emerged from the three field experiments: (a) Pathogen antagonism by endophytes can be preempted by host genes for resistance that suppress pathogen development, and (b) pathogen antagonism by endophytes can secondarily be preempted by competitive exclusion of the rust by the mite. Synthesis: Our results point to a Populus defense hierarchy with resistance genes on top, followed by pathogen competition, and finally pathogen antagonism by endophytes. We expect these rules will help to explain the variation in pathogen antagonism that is currently attributed to context dependency.
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Affiliation(s)
- Posy E. Busby
- Botany and Plant Pathology DepartmentOregon State UniversityCorvallisOregon
| | - Gregory Crutsinger
- Department of ZoologyUniversity of British ColumbiaVancouverBritish Columbia
| | - Matthew Barbour
- Department of ZoologyUniversity of British ColumbiaVancouverBritish Columbia
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23
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Zhang L, Shang J, Jia Q, Li K, Yang H, Liu H, Tang Z, Chang X, Zhang M, Wang W, Yang W. Genetic evolutionary analysis of soybean mosaic virus populations from three geographic locations in China based on the P1 and CP genes. Arch Virol 2019; 164:1037-1048. [PMID: 30747339 DOI: 10.1007/s00705-019-04165-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 01/11/2019] [Indexed: 01/14/2023]
Abstract
Soybean mosaic virus (SMV) is one of the major pathogens causing serious soybean losses. Little is known about the genetic structure and evolutionary biology of the SMV population in southwestern China. In this study, 29 SMV isolates were obtained from Sichuan Province, and the genomic regions encoding the first protein (P1) and coat protein (CP) were sequenced. Combined with SMV isolates from the southeastern and northeastern regions of China, the genetic and molecular evolution of SMV was studied. Recombination analysis revealed that intraspecific and interspecific recombination had occurred in the SMV population. A phylogenetic tree based on the P1 gene reflected the geographic origin of the non-interspecific recombinant SMV (SMV-NI), while a tree based on the CP gene did not. Though frequent gene flow of the SMV-NI populations was found between the southeastern and northeastern populations, the southwestern population was relatively independent. Genetic differentiation was significant between the SMV interspecific recombinant (SMV-RI) and the non-interspecific recombinant (SMV-NI) populations. It was interesting to note that there was an almost identical recombination breakpoint in SMV-RI and Watermelon mosaic virus (WMV). Population dynamics showed that SMV-RI might be in an expanding state, while the SMV-NI population is relatively stable.
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Affiliation(s)
- Lei Zhang
- Sichuan Engineering Research Center for Crop Strip Intercropping System and Key Laboratory of Crop Eco‑physiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, 611130, China
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Jing Shang
- Sichuan Engineering Research Center for Crop Strip Intercropping System and Key Laboratory of Crop Eco‑physiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, 611130, China.
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China.
| | - Qi Jia
- Sichuan Engineering Research Center for Crop Strip Intercropping System and Key Laboratory of Crop Eco‑physiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, 611130, China
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Kai Li
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean, Ministry of Agriculture, Nanjing Agricultural University, Weigang 1, Nanjing, 210095, China
| | - Hui Yang
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Huanhuan Liu
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Zhongqin Tang
- Sichuan Engineering Research Center for Crop Strip Intercropping System and Key Laboratory of Crop Eco‑physiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, 611130, China
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Xiaoli Chang
- Sichuan Engineering Research Center for Crop Strip Intercropping System and Key Laboratory of Crop Eco‑physiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, 611130, China
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Min Zhang
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Wenming Wang
- College of Agronomy and Key Laboratory for Major Crop Diseases, Sichuan Agricultural University, Chengdu, 611130, China
| | - Wenyu Yang
- Sichuan Engineering Research Center for Crop Strip Intercropping System and Key Laboratory of Crop Eco‑physiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, 611130, China.
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24
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Drott MT, Debenport T, Higgins SA, Buckley DH, Milgroom MG. Fitness Cost of Aflatoxin Production in Aspergillus flavus When Competing with Soil Microbes Could Maintain Balancing Selection. mBio 2019; 10:e02782-18. [PMID: 30782658 PMCID: PMC6381279 DOI: 10.1128/mbio.02782-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 01/08/2019] [Indexed: 02/08/2023] Open
Abstract
Selective forces that maintain the polymorphism for aflatoxigenic and nonaflatoxigenic individuals of Aspergillus flavus are largely unknown. As soils are widely considered the natural habitat of A. flavus, we hypothesized that aflatoxin production would confer a fitness advantage in the soil environment. To test this hypothesis, we used A. flavus DNA quantified by quantitative PCR (qPCR) as a proxy for fitness of aflatoxigenic and nonaflatoxigenic field isolates grown in soil microcosms. Contrary to predictions, aflatoxigenic isolates had significantly lower fitness than did nonaflatoxigenic isolates in natural soils across three temperatures (25, 37, and 42°C). The addition of aflatoxin to soils (500 ng/g) had no effect on the growth of A. flavus Amplicon sequencing showed that neither the aflatoxin-producing ability of the fungus nor the addition of aflatoxin had a significant effect on the composition of fungal or bacterial communities in soil. We argue that the fitness disadvantage of aflatoxigenic isolates is most likely explained by the metabolic cost of producing aflatoxin. Coupled with a previous report of a selective advantage of aflatoxin production in the presence of some insects, our findings give an ecological explanation for balancing selection resulting in persistent polymorphisms in aflatoxin production.IMPORTANCE Aflatoxin, produced by the fungus Aspergillus flavus, is an extremely potent hepatotoxin that causes acute toxicosis and cancer, and it incurs hundreds of millions of dollars annually in agricultural losses. Despite the importance of this toxin to humans, it has remained unclear what the fungus gains by producing aflatoxin. In fact, not all strains of A. flavus produce aflatoxin. Previous work has shown an advantage to producing aflatoxin in the presence of some insects. Our current work demonstrates the first evidence of a disadvantage to A. flavus in producing aflatoxin when competing with soil microbes. Together, these opposing evolutionary forces could explain the persistence of both aflatoxigenic and nonaflatoxigenic strains through evolutionary time.
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Affiliation(s)
- Milton T Drott
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, New York, USA
| | - Tracy Debenport
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, New York, USA
| | - Steven A Higgins
- School of Integrative Plant Science, Soil and Crop Sciences Section, Cornell University, Ithaca, New York, USA
| | - Daniel H Buckley
- School of Integrative Plant Science, Soil and Crop Sciences Section, Cornell University, Ithaca, New York, USA
| | - Michael G Milgroom
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, New York, USA
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25
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The global burden of pathogens and pests on major food crops. Nat Ecol Evol 2019; 3:430-439. [PMID: 30718852 DOI: 10.1038/s41559-018-0793-y] [Citation(s) in RCA: 1091] [Impact Index Per Article: 218.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 12/20/2018] [Indexed: 11/08/2022]
Abstract
Crop pathogens and pests reduce the yield and quality of agricultural production. They cause substantial economic losses and reduce food security at household, national and global levels. Quantitative, standardized information on crop losses is difficult to compile and compare across crops, agroecosystems and regions. Here, we report on an expert-based assessment of crop health, and provide numerical estimates of yield losses on an individual pathogen and pest basis for five major crops globally and in food security hotspots. Our results document losses associated with 137 pathogens and pests associated with wheat, rice, maize, potato and soybean worldwide. Our yield loss (range) estimates at a global level and per hotspot for wheat (21.5% (10.1-28.1%)), rice (30.0% (24.6-40.9%)), maize (22.5% (19.5-41.1%)), potato (17.2% (8.1-21.0%)) and soybean (21.4% (11.0-32.4%)) suggest that the highest losses are associated with food-deficit regions with fast-growing populations, and frequently with emerging or re-emerging pests and diseases. Our assessment highlights differences in impacts among crop pathogens and pests and among food security hotspots. This analysis contributes critical information to prioritize crop health management to improve the sustainability of agroecosystems in delivering services to societies.
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Moreira RR, Peres NA, May De Mio LL. Colletotrichum acutatum and C. gloeosporioides Species Complexes Associated with Apple in Brazil. PLANT DISEASE 2019; 103:268-275. [PMID: 30484753 DOI: 10.1094/pdis-07-18-1187-re] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Glomerella leaf spot (GLS) is an apple disease that concerns growers due to the increases in severity over the years and the difficulties in control. Species within the Colletotrichum acutatum and C. gloeosporioides species complexes cause GLS, but the proportion of species within each complex in Brazilian apple orchards is not known. The objectives of this study were to identify isolates of Colletotrichum causing GLS on apple orchards in the main Brazilian producing regions to the species level. Two hundred and seven isolates were obtained in orchards in São Paulo (SP), Parana (PR), Santa Catarina (SC), and Rio Grande do Sul (RS) states. Genomic DNA was extracted, and the ITS, GAPDH, CHS-1, and TUB2 genes were amplified and sequenced. The phylogenetic trees were generated using a concatenated alignment. One hundred and fourteen isolates were identified as belonging to the C. acutatum species complex (Cac) and 93 to the C. gloeosporioides species complex (Cgc). Five phylogenetic species were identified: C. melonis (1.9%), C. nymphaeae (47.4%), C. paranaense (2.4%), C. limetticola (3.4%), and C. fructicola (44.9%). In SC, Cgc predominates, but in the states of SP, PR, and RS, Cac was predominant. This is the first report of C. limetticola from apple.
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Affiliation(s)
- Rafaele R Moreira
- Universidade Federal do Paraná, Setor de Ciências Agrárias (SCA-DFF), Curitiba, PR 80035-050, Brazil
| | - Natalia A Peres
- University of Florida, Gulf Coast Research and Education Center (GCREC-UF), Wimauma, FL 33598
| | - Louise L May De Mio
- Universidade Federal do Paraná, Setor de Ciências Agrárias (SCA-DFF), Curitiba, PR 80035-050, Brazil
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27
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Jenkinson TS, Rodriguez D, Clemons RA, Michelotti LA, Zamudio KR, Toledo LF, Longcore JE, James TY. Globally invasive genotypes of the amphibian chytrid outcompete an enzootic lineage in coinfections. Proc Biol Sci 2018; 285:20181894. [PMID: 30963903 PMCID: PMC6304064 DOI: 10.1098/rspb.2018.1894] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/19/2018] [Indexed: 01/22/2023] Open
Abstract
Competition between genotypes is likely to be a key driver of pathogen evolution, particularly following a geographical invasion by distant strains. Theory predicts that competition between disease strains will result in the most virulent strain persisting. Despite its evolutionary implications, the role of strain competition in shaping populations remains untested for most pathogens. We experimentally investigated the in vivo competitive differences between two divergent lineages of the amphibian-killing chytrid fungus ( Batrachochytrium dendrobatidis, Bd). These Bd lineages are hypothesized to have diverged in allopatry but been recently brought back into secondary contact by human introduction. Prior studies indicate that a panzootically-distributed, global lineage of Bd was recently introduced into southern Brazil, and is competitively excluding enzootic lineages in the southern Atlantic Forest. To test for differences in competitive ability between invasive and enzootic Brazilian Bd isolates, we coinfected a model host frog system which we developed for this study ( Hymenochirus curtipes). We tracked isolate-specific zoospore production over the course of the coinfection experiment with chip-based digital PCR (dPCR). The globally invasive panzootic lineage had a competitive advantage in spore production especially during the first one to four weeks of infection, and on frogs that eventually succumbed to Bd infection. Our study provides new evidence that competitive pressure resulting from the human movement of pathogen strains can rapidly alter the genetics, community dynamics and spatial epidemiology of pathogens in the wild.
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Affiliation(s)
- Thomas S. Jenkinson
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - David Rodriguez
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Rebecca A. Clemons
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lucas A. Michelotti
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kelly R. Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - L. Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP 13083-862, Brazil
| | - Joyce E. Longcore
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA
| | - Timothy Y. James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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28
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Yang N, Ma G, Chen K, Wu X. The Population Genetics of Alternaria tenuissima in Four Regions of China as Determined by Microsatellite Markers Obtained by Transcriptome Sequencing. Front Microbiol 2018; 9:2904. [PMID: 30559728 PMCID: PMC6287023 DOI: 10.3389/fmicb.2018.02904] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 11/13/2018] [Indexed: 12/02/2022] Open
Abstract
A total of 32,284 unigenes were obtained from the transcriptome of Alternaria tenuissima, a pathogenic fungus causing foliar disease in tomato, using next-generation sequencing (NGS) technology. In total, 24,670 unigenes were annotated using five databases, including NCBI non-redundant protein, Swiss-Prot, euKaryotic Orthologous Groups, Kyoto Encyclopedia of Genes and Genomes, and the Gene Ontology. A total of 1,140 simple sequence repeats were also identified for use as molecular markers. Sixteen of the simple sequence repeat loci were selected to study the population structure of A. tenuissima. A population genetic analysis of 191 A. tenuissima isolates, sampled from four geographic regions in China, indicated that A. tenuissima had a high level of genetic diversity, and that the selected simple sequence repeat markers could reliably capture the genetic variation. The null hypothesis of random mating was rejected for all four geographic regions in China. Isolation by distance was observed for the entire data set, but not within clusters, which is indicative of barriers to gene flow among geographic regions. The analyses of Bayesian and principal coordinates, however, did not separate four geographic regions into four separate genetic clusters. The different levels of historical migration rates suggest that isolation by distance did not represent a major biological obstacle to the spread of A. tenuissima. The potential epidemic spread of A. tenuissima in China may occur through the transport of plant products or other factors. The presented results provide a basis for a comprehensive understanding of the population genetics of A. tenuissima in China.
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Affiliation(s)
| | | | | | - Xuehong Wu
- College of Plant Protection, Department of Plant Pathology, China Agricultural University, Beijing, China
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29
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Halliday FW, Umbanhowar J, Mitchell CE. A host immune hormone modifies parasite species interactions and epidemics: insights from a field manipulation. Proc Biol Sci 2018; 285:rspb.2018.2075. [PMID: 30404885 DOI: 10.1098/rspb.2018.2075] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/18/2018] [Indexed: 12/12/2022] Open
Abstract
Parasite epidemics can depend on priority effects, and parasite priority effects can result from the host immune response to prior infection. Yet we lack experimental evidence that such immune-mediated priority effects influence epidemics. To address this research gap, we manipulated key host immune hormones, then measured the consequences for within-host parasite interactions, and ultimately parasite epidemics in the field. Specifically, we applied plant immune-signalling hormones to sentinel plants, embedded into a wild host population, and tracked foliar infections caused by two common fungal parasites. Within-host individuals, priority effects were altered by the immune-signalling hormone, salicylic acid (SA). Scaling up from within-host interactions, hosts treated with SA experienced a lower prevalence of a less aggressive parasite, increased burden of infection by a more aggressive parasite, and experienced fewer co-infections. Together, these results indicate that by altering within-host priority effects, host immune hormones can drive parasite epidemics. This study therefore experimentally links host immune hormones to within-host priority effects and parasite epidemics, advancing a more mechanistic understanding of how interactions among parasites alter their epidemics.
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Affiliation(s)
- Fletcher W Halliday
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - James Umbanhowar
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.,Curriculum for the Environment and Ecology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Charles E Mitchell
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.,Curriculum for the Environment and Ecology, University of North Carolina, Chapel Hill, NC 27599, USA
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30
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Bousset L, Sprague SJ, Thrall PH, Barrett LG. Spatio-temporal connectivity and host resistance influence evolutionary and epidemiological dynamics of the canola pathogen Leptosphaeria maculans. Evol Appl 2018; 11:1354-1370. [PMID: 30151045 PMCID: PMC6099830 DOI: 10.1111/eva.12630] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 03/07/2018] [Indexed: 11/27/2022] Open
Abstract
Genetic, physiological and physical homogenization of agricultural landscapes creates ideal environments for plant pathogens to proliferate and rapidly evolve. Thus, a critical challenge in plant pathology and epidemiology is to design durable and effective strategies to protect cropping systems from damage caused by pathogens. Theoretical studies suggest that spatio-temporal variation in the diversity and distribution of resistant hosts across agricultural landscapes may have strong effects on the epidemiology and evolutionary potential of crop pathogens. However, we lack empirical tests of spatio-temporal deployment of host resistance to pathogens can be best used to manage disease epidemics and disrupt pathogen evolutionary dynamics in real-world systems. In a field experiment, we simulated how differences in Brassica napus resistance deployment strategies and landscape connectivity influence epidemic severity and Leptosphaeria maculans pathogen population composition. Host plant resistance, spatio-temporal connectivity [stubble loads], and genetic connectivity of the inoculum source [composition of canola stubble mixtures] jointly impacted epidemiology (disease severity) and pathogen evolution (population composition). Changes in population composition were consistent with directional selection for the ability to infect the host (infectivity), leading to changes in pathotype (multilocus phenotypes) and infectivity frequencies. We repeatedly observed decreases in the frequency of unnecessary infectivity, suggesting that carrying multiple infectivity genes is costly for the pathogen. From an applied perspective, our results indicate that varying resistance genes in space and time can be used to help control disease, even when resistance has already been overcome. Furthermore, our approach extends our ability to test not only for the efficacy of host varieties in a given year, but also for durability over multiple cropping seasons, given variation in the combination of resistance genes deployed.
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Affiliation(s)
- Lydia Bousset
- CSIRO Agriculture & FoodCanberraACTAustralia
- UMR1349 IGEPPINRALe RheuFrance
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31
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Hawkins NJ, Fraaije BA. Fitness Penalties in the Evolution of Fungicide Resistance. ANNUAL REVIEW OF PHYTOPATHOLOGY 2018; 56:339-360. [PMID: 29958074 DOI: 10.1146/annurev-phyto-080417-050012] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The evolution of resistance poses an ongoing threat to crop protection. Fungicide resistance provides a selective advantage under fungicide selection, but resistance-conferring mutations may also result in fitness penalties, resulting in an evolutionary trade-off. These penalties may result from the functional constraints of an evolving target site or from the resource allocation costs of overexpression or active transport. The extent to which such fitness penalties are present has important implications for resistance management strategies, determining whether resistance persists or declines between treatments, and for resistance risk assessments for new modes of action. Experimental results have proven variable, depending on factors such as temperature, nutrient status, osmotic or oxidative stress, and pathogen life-cycle stage. Functional genetics tools allow pathogen genetic background to be controlled, but this in turn raises the question of epistatic interactions. Combining fitness penalties under various conditions into a field-realistic scenario poses an important future challenge.
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Affiliation(s)
- N J Hawkins
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom;
| | - B A Fraaije
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom;
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32
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Suffert F, Goyeau H, Sache I, Carpentier F, Gélisse S, Morais D, Delestre G. Epidemiological trade-off between intra- and interannual scales in the evolution of aggressiveness in a local plant pathogen population. Evol Appl 2018; 11:768-780. [PMID: 29875818 PMCID: PMC5979725 DOI: 10.1111/eva.12588] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 11/30/2017] [Indexed: 01/15/2023] Open
Abstract
The efficiency of plant resistance to fungal pathogen populations is expected to decrease over time, due to their evolution with an increase in the frequency of virulent or highly aggressive strains. This dynamics may differ depending on the scale investigated (annual or pluriannual), particularly for annual crop pathogens with both sexual and asexual reproduction cycles. We assessed this time-scale effect, by comparing aggressiveness changes in a local Zymoseptoria tritici population over an 8-month cropping season and a 6-year period of wheat monoculture. We collected two pairs of subpopulations to represent the annual and pluriannual scales: from leaf lesions at the beginning and end of a single annual epidemic and from crop debris at the beginning and end of a 6-year period. We assessed two aggressiveness traits-latent period and lesion size-on sympatric and allopatric host varieties. A trend toward decreased latent period concomitant with a significant loss of variability was established during the course of the annual epidemic, but not over the 6-year period. Furthermore, a significant cultivar effect (sympatric vs. allopatric) on the average aggressiveness of the isolates revealed host adaptation, arguing that the observed patterns could result from selection. We thus provide an experimental body of evidence of an epidemiological trade-off between the intra- and interannual scales in the evolution of aggressiveness in a local plant pathogen population. More aggressive isolates were collected from upper leaves, on which disease severity is usually lower than on the lower part of the plants left in the field as crop debris after harvest. We suggest that these isolates play little role in sexual reproduction, due to an Allee effect (difficulty finding mates at low pathogen densities), particularly as the upper parts of the plant are removed from the field, explaining the lack of transmission of increases in aggressiveness between epidemics.
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Affiliation(s)
- Frédéric Suffert
- UMR BIOGER, INRA, AgroParisTechUniversité Paris‐SaclayThiverval‐GrignonFrance
| | - Henriette Goyeau
- UMR BIOGER, INRA, AgroParisTechUniversité Paris‐SaclayThiverval‐GrignonFrance
| | - Ivan Sache
- UMR BIOGER, INRA, AgroParisTechUniversité Paris‐SaclayThiverval‐GrignonFrance
| | - Florence Carpentier
- UMR BIOGER, INRA, AgroParisTechUniversité Paris‐SaclayThiverval‐GrignonFrance
| | - Sandrine Gélisse
- UMR BIOGER, INRA, AgroParisTechUniversité Paris‐SaclayThiverval‐GrignonFrance
| | - David Morais
- UMR BIOGER, INRA, AgroParisTechUniversité Paris‐SaclayThiverval‐GrignonFrance
| | - Ghislain Delestre
- UMR BIOGER, INRA, AgroParisTechUniversité Paris‐SaclayThiverval‐GrignonFrance
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33
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Bai BB, Liu TG, Liu B, Gao L, Chen WQ. High Relative Parasitic Fitness of G22 Derivatives is Associated with the Epidemic Potential of Wheat Stripe Rust in China. PLANT DISEASE 2018; 102:483-487. [PMID: 30673484 DOI: 10.1094/pdis-04-17-0511-sr] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In total, 13 commercial wheat cultivars around China and four races of Puccinia striiformis f. sp. tritici (namely, CYR32, CYR33, G22-9, and G22-14) were employed for a test of relative parasitic fitness (RPF) using the drop method. The RPF values were measured, including the urediniospore germination rate, the latent period, the uredinial length, the uredinial density, the infection area, the sporulation intensity, the lesion expansion speed, and the sporulation period. The results indicated that the parameters of relative parasitic fitness of the four P. striiformis f. sp. tritici races on the 13 wheat cultivars were significantly different (P = 0.00) in sporulation intensity, lesion expansion speed, uredinial length, sporulation period, uredinial density, and latent period. The urediniospore germination rates of the four P. striiformis f. sp. tritici races for the test were significantly different (P = 0.00), whereas no correlation with the different cultivars was observed (P = 1.00). The infection areas of the tested races on the different cultivars were significantly different (P = 0.00) but there were no obvious manifestations among the various races (P = 0.20). Principal component analysis (PCA) showed that the sporulation intensity represented sporulation capacity and scalability, the latent period indicated infection ability, and the urediniospore germination rate represented urediniospore vigor, all of which fully contributed to the RPF in the interaction of the four races and 13 wheat cultivars, which was calculated by the following formula: RPF = (sporulation intensity × urediniospore germination rate)/latent period. The sporulation and infection of G22-9 on the 13 large-scale cultivated cultivars were the highest, and the RPF of G22-9 was higher than that of the predominant races, CYR32 and CYR33. This result suggested that G22-9 could become a new predominant race and potentially cause epidemics of wheat stripe rust in China. To prevent potential epidemics, susceptible wheat cultivars should be withdrawn from production and breeding programs should reduce the use of Yr10 and Yr26 and use other more effective resistance genes in combination with nonrace-specific resistance for developing wheat cultivars with durable resistance to stripe rust.
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Affiliation(s)
- Bing Bing Bai
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Tai Guo Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Bo Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Li Gao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Wan Quan Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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Schweizer G, Münch K, Mannhaupt G, Schirawski J, Kahmann R, Dutheil JY. Positively Selected Effector Genes and Their Contribution to Virulence in the Smut Fungus Sporisorium reilianum. Genome Biol Evol 2018; 10:629-645. [PMID: 29390140 PMCID: PMC5811872 DOI: 10.1093/gbe/evy023] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2018] [Indexed: 12/13/2022] Open
Abstract
Plants and fungi display a broad range of interactions in natural and agricultural ecosystems ranging from symbiosis to parasitism. These ecological interactions result in coevolution between genes belonging to different partners. A well-understood example is secreted fungal effector proteins and their host targets, which play an important role in pathogenic interactions. Biotrophic smut fungi (Basidiomycota) are well-suited to investigate the evolution of plant pathogens, because several reference genomes and genetic tools are available for these species. Here, we used the genomes of Sporisorium reilianum f. sp. zeae and S. reilianum f. sp. reilianum, two closely related formae speciales infecting maize and sorghum, respectively, together with the genomes of Ustilago hordei, Ustilago maydis, and Sporisorium scitamineum to identify and characterize genes displaying signatures of positive selection. We identified 154 gene families having undergone positive selection during species divergence in at least one lineage, among which 77% were identified in the two investigated formae speciales of S. reilianum. Remarkably, only 29% of positively selected genes encode predicted secreted proteins. We assessed the contribution to virulence of nine of these candidate effector genes in S. reilianum f. sp. zeae by deleting individual genes, including a homologue of the effector gene pit2 previously characterized in U. maydis. Only the pit2 deletion mutant was found to be strongly reduced in virulence. Additional experiments are required to understand the molecular mechanisms underlying the selection forces acting on the other candidate effector genes, as well as the large fraction of positively selected genes encoding predicted cytoplasmic proteins.
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Affiliation(s)
- Gabriel Schweizer
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Karin Münch
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Gertrud Mannhaupt
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Institute for Bioinformatics and Systems Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Jan Schirawski
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Microbial Genetics, Institute of Applied Microbiology, RWTH Aachen, Aachen, Germany
| | - Regine Kahmann
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Julien Y Dutheil
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Institute of Evolutionary Sciences of Montpellier, “Genome” Department, CNRS, University of Montpellier 2, France
- Research Group Molecular Systems Evolution, Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
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35
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Macedo R, Sales LP, Yoshida F, Silva-Abud LL, Lobo M. Potential worldwide distribution of Fusarium dry root rot in common beans based on the optimal environment for disease occurrence. PLoS One 2017; 12:e0187770. [PMID: 29107985 PMCID: PMC5673228 DOI: 10.1371/journal.pone.0187770] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/25/2017] [Indexed: 12/11/2022] Open
Abstract
Root rots are a constraint for staple food crops and a long-lasting food security problem worldwide. In common beans, yield losses originating from root damage are frequently attributed to dry root rot, a disease caused by the Fusarium solani species complex. The aim of this study was to model the current potential distribution of common bean dry root rot on a global scale and to project changes based on future expectations of climate change. Our approach used a spatial proxy of the field disease occurrence, instead of solely the pathogen distribution. We modeled the pathogen environmental requirements in locations where in-situ inoculum density seems ideal for disease manifestation. A dataset of 2,311 soil samples from commercial farms assessed from 2002 to 2015 allowed us to evaluate the environmental conditions associated with the pathogen's optimum inoculum density for disease occurrence, using a lower threshold as a spatial proxy. We encompassed not only the optimal conditions for disease occurrence but also the optimal pathogen's density required for host infection. An intermediate inoculum density of the pathogen was the best disease proxy, suggesting density-dependent mechanisms on host infection. We found a strong convergence on the environmental requirements of both the host and the disease development in tropical areas, mostly in Brazil, Central America, and African countries. Precipitation and temperature variables were important for explaining the disease occurrence (from 17.63% to 43.84%). Climate change will probably move the disease toward cooler regions, which in Brazil are more representative of small-scale farming, although an overall shrink in total area (from 48% to 49% in 2050 and 26% to 41% in 2070) was also predicted. Understanding pathogen distribution and disease risks in an evolutionary context will therefore support breeding for resistance programs and strategies for dry root rot management in common beans.
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Affiliation(s)
- Renan Macedo
- Universidade Federal de Goiás, Escola de Agronomia e Engenharia de Alimentos, Goiânia, GO, Brazil
| | - Lilian Patrícia Sales
- Universidade Federal de Goiás, Departamento de Ecologia e Evolução, Goiânia, GO, Brazil
| | - Fernanda Yoshida
- Universidade Federal de Goiás, Escola de Agronomia e Engenharia de Alimentos, Goiânia, GO, Brazil
| | | | - Murillo Lobo
- Empresa Brasileira de Pesquisa Agropecuária–Embrapa Arroz e Feijão, Santo Antônio de Goiás, GO, Brazil
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Halliday FW, Umbanhowar J, Mitchell CE. Interactions among symbionts operate across scales to influence parasite epidemics. Ecol Lett 2017; 20:1285-1294. [DOI: 10.1111/ele.12825] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 07/23/2017] [Indexed: 12/31/2022]
Affiliation(s)
| | - James Umbanhowar
- Department of Biology University of North Carolina Chapel Hill NC27599 USA
- Curriculum for the Environment and Ecology University of North Carolina Chapel Hill NC27599 USA
| | - Charles E. Mitchell
- Department of Biology University of North Carolina Chapel Hill NC27599 USA
- Curriculum for the Environment and Ecology University of North Carolina Chapel Hill NC27599 USA
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Vieira WADS, Lima WG, Nascimento ES, Michereff SJ, Reis A, Doyle VP, Câmara MPS. Thiophanate-Methyl Resistance and Fitness Components of Colletotrichum musae Isolates from Banana in Brazil. PLANT DISEASE 2017; 101:1659-1665. [PMID: 30677331 DOI: 10.1094/pdis-11-16-1594-re] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Anthracnose, caused by Colletotrichum musae, is the most important postharvest disease of banana and is widely distributed among the banana production regions in Brazil. Although thiophanate-methyl is a fungicide frequently used in Brazilian banana orchards to control Sigatoka leaf spot, Collettotrichum populations are also exposed, resulting in the evolution of fungicide resistance and the inability to manage banana anthracnose. We investigated 139 Brazilian isolates of C. musae for thiophanate-methyl sensitivity in vitro. The 50% mycelial growth inhibition (EC50) values varied between 0.003 and 48.73 μg/ml. One-hundred and thirty isolates were classified as sensitive, with EC50 values ranging from 0.003 to 4.84 μg/ml, while the remaining nine isolates were considered moderately resistant, with EC50 values ranging between 10.43 and 48.73 μg/ml. Resistant or highly resistant isolates (EC50 > 100 μg/ml) were not found. A substitution of TAC for TTC at codon 200 in a coding region of the β-tubulin gene was associated with the moderately resistant phenotype. Applications of thiophanate-methyl formulation to detached banana fruit at the label rate (500 μg/ml) showed low efficacy in controlling the moderately resistant isolates on banana fruits. However, there is no indication of a reduction in fitness associated with fungicide resistance as sensitive and moderately resistant isolates do not differ with respect to mycelial growth rate (P = 0.098), spore production (P = 0.066), spore germination (P = 0.366), osmotic sensitivity (P = 0.051), and virulence (P = 0.057). Our results revealed absence of adaptability cost for the moderately resistant isolates, suggesting that they can be dominant in population if the fungicide continue to be applied.
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Affiliation(s)
| | - Waléria Guerreiro Lima
- Departamento de Agronomia, Universidade Federal Rural de Pernambuco, Recife, 52171-900, Pernambuco, Brazil
| | - Eduardo Souza Nascimento
- Departamento de Agronomia, Universidade Federal Rural de Pernambuco, Recife, 52171-900, Pernambuco, Brazil
| | - Sami Jorge Michereff
- Departamento de Agronomia, Universidade Federal Rural de Pernambuco, Recife, 52171-900, Pernambuco, Brazil
| | - Ailton Reis
- Departamento de Agronomia, Universidade Federal Rural de Pernambuco, Recife, 52171-900, Pernambuco, Brazil
| | - Vinson P Doyle
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA 70803
| | - Marcos Paz Saraiva Câmara
- Departamento de Agronomia, Universidade Federal Rural de Pernambuco, Recife, 52171-900, Pernambuco, Brazil
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Gao F, Zou W, Xie L, Zhan J. Adaptive evolution and demographic history contribute to the divergent population genetic structure of Potato virus Y between China and Japan. Evol Appl 2017; 10:379-390. [PMID: 28352297 PMCID: PMC5367074 DOI: 10.1111/eva.12459] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 01/10/2017] [Indexed: 12/22/2022] Open
Abstract
Potato virus Y (PVY) is an important plant pathogen causing considerable economic loss to potato production. Knowledge of the population genetic structure and evolutionary biology of the pathogen, particularly at a transnational scale, is limited but vital in developing sustainable management schemes. In this study, the population genetic structure and molecular evolution of PVY were studied using 127 first protein (P1) and 137 coat protein (CP) sequences generated from isolates collected from potato in China and Japan. High genetic differentiation was found between the populations from the two countries, with higher nucleotide diversity in Japan than China in both genes and a KST value of .216 in the concatenated sequences of the two genes. Sequences from the two countries clustered together according to their geographic origin. Further analyses showed that spatial genetic structure in the PVY populations was likely caused by demographic dynamics of the pathogen and natural selection generated by habitat heterogeneity. Purifying selection was detected at the majority of polymorphic sites although some clade-specific codons were under positive selection. In past decades, PVY has undergone a population expansion in China, whereas in Japan, the population size of the pathogen has remained relatively constant.
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Affiliation(s)
- Fangluan Gao
- Fujian Key Laboratory of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - Wenchao Zou
- Fujian Key Laboratory of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - Lianhui Xie
- Fujian Key Laboratory of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
| | - Jiasui Zhan
- Fujian Key Laboratory of Plant VirologyInstitute of Plant VirologyFujian Agriculture and Forestry UniversityFuzhouChina
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Kröner A, Mabon R, Corbière R, Montarry J, Andrivon D. The coexistence of generalist and specialist clonal lineages in natural populations of the Irish Famine pathogen Phytophthora infestans explains local adaptation to potato and tomato. Mol Ecol 2017; 26:1891-1901. [PMID: 28052487 DOI: 10.1111/mec.14004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/24/2016] [Accepted: 11/01/2016] [Indexed: 12/19/2022]
Abstract
Phytophthora infestans, causing late blight on Solanaceae, is a serious threat to potato and tomato crops worldwide. P. infestans populations sampled on either potato or tomato differ in genotypes and pathogenicity, suggesting niche exclusion in the field. We hypothesized that such niche separation can reflect differential host exploitation by different P. infestans genotypes. We thus compared genotypes and phenotypes in 21 isolates sampled on potato (n = 11) or tomato (n = 10). Typing at 12 microsatellite loci assigned potato isolates to the 13_A2, 6_A1 and 1_A1 lineages, and tomato isolates to the 23_A1, 2_A1 and unclassified multilocus genotypes. Cross-inoculations on potato and tomato leaflets showed that all isolates were pathogenic on both hosts. However, tomato isolates performed much better on tomato than did potato isolates, which performed better on potato than did tomato isolates, thus revealing a clear pattern of local adaptation. Potato isolates were significantly fitter on potato than on tomato, and are best described as potato specialists; tomato isolates appear to be generalists, with similar pathogenicity on both hosts. Niche separation in the field may thus result mainly from the large fitness gap on tomato between generalists and unadapted potato specialists, while the small, but significant fitness difference on potato between both types of isolates may prevent population invasion by generalists. Extreme specialization to potato seems very costly relative to performance loss on the alternative host. This study therefore shows that local adaptation and niche separation, commonly expected to involve and generate specialists, can occur with generalists.
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Le Lam TN, Morvan C, Liu W, Bohn C, Jaszczyszyn Y, Bouloc P. Finding sRNA-associated phenotypes by competition assays: An example with Staphylococcus aureus. Methods 2016; 117:21-27. [PMID: 27916561 DOI: 10.1016/j.ymeth.2016.11.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 11/23/2016] [Accepted: 11/30/2016] [Indexed: 01/05/2023] Open
Abstract
Bacteria optimize their fitness in response to a changing environment by tight regulation of gene expression. Regulation can be controlled at both transcriptional and post-transcriptional levels via key players such as sigma factors, regulatory proteins and regulatory RNAs. The identification of phenotypes associated with gene deletions is the established method for finding gene functions but may require testing many conditions for each studied mutant. As regulatory RNAs often contribute to fine-tuning gene expression, phenotypes associated with their inactivation are often weak and difficult to detect. Nevertheless, minor phenotypes conferring modest advantages, may allow bacteria to emerge after some generations under selective pressure. A strategy employing DNA barcodes can be used to perform competition experiments between mutants and to monitor fitness associated with mutations in different growth conditions. We combined this strategy with deep sequencing to study regulatory RNAs in Staphylococcus aureus, a major opportunistic pathogen.
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Affiliation(s)
- Thao Nguyen Le Lam
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Claire Morvan
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Wenfeng Liu
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Chantal Bohn
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Yan Jaszczyszyn
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Philippe Bouloc
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France.
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41
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Klosowski AC, Brahm L, Stammler G, De Mio LLM. Competitive Fitness of Phakopsora pachyrhizi Isolates with Mutations in the CYP51 and CYTB Genes. PHYTOPATHOLOGY 2016; 106:1278-1284. [PMID: 27359265 DOI: 10.1094/phyto-01-16-0008-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Soybean rust (Phakopsora pachyrhizi) in Brazil is mainly controlled with applications of fungicides, including demethylation inhibitors (DMI) and quinone outside inhibitors (QoI). Isolates with less sensitivity to DMI and QoI have been reported, and these have been found to have mutations in the CYP51 and CYTB genes, respectively. There have been no reports of fitness costs in isolates with mutations in CYP51 and CYTB, and the aim of this work was to compare the competitive ability of isolates with lower DMI or QoI sensitivities with that of sensitive (wild-type) isolates. Urediniospores of sensitive wild-type isolates and isolates with different CYP51 or CYTB alleles were mixed and inoculated on detached soybean leaves. After 3 weeks, urediniospores were harvested and used as inoculum for the next disease cycle. Frequencies of relevant target site mutations were monitored using the pyrosequencing method over four disease cycles. Isolates with lower DMI sensitivity and different CYP51 alleles had competitive disadvantages compared with a DMI-sensitive, wild-type CYP51 isolate. In contrast, the isolate with the F129L mutation in the CYTB gene competed equally well with a QoI-sensitive, wild-type CYTB isolate under the conditions of this experiment. The CYP51 and CYTB alleles were stable in all isolates over four disease cycles when cultivated alone.
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Affiliation(s)
- Ana C Klosowski
- First and fourth authors: Universidade Federal do Paraná, Rua dos Funcionários 1540, 80035-050 Curitiba, Brazil; second and third authors: BASF SE, Fungicide Research, Agricultural Center Limburgerhof, D-67117, Germany
| | - Lutz Brahm
- First and fourth authors: Universidade Federal do Paraná, Rua dos Funcionários 1540, 80035-050 Curitiba, Brazil; second and third authors: BASF SE, Fungicide Research, Agricultural Center Limburgerhof, D-67117, Germany
| | - Gerd Stammler
- First and fourth authors: Universidade Federal do Paraná, Rua dos Funcionários 1540, 80035-050 Curitiba, Brazil; second and third authors: BASF SE, Fungicide Research, Agricultural Center Limburgerhof, D-67117, Germany
| | - Louise L May De Mio
- First and fourth authors: Universidade Federal do Paraná, Rua dos Funcionários 1540, 80035-050 Curitiba, Brazil; second and third authors: BASF SE, Fungicide Research, Agricultural Center Limburgerhof, D-67117, Germany
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42
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Zhan F, Xie Y, Zhu W, Sun D, McDonald BA, Zhan J. Linear Correlation Analysis of Zymoseptoria tritici Aggressiveness with In Vitro Growth Rate. PHYTOPATHOLOGY® 2016; 106:1255-1261. [PMID: 27348342 DOI: 10.1094/phyto-12-15-0338-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Zymoseptoria tritici is a globally distributed plant-pathogenic fungus causing Septoria tritici blotch of wheat. In this study, the in vitro growth rates and aggressiveness of 141 genetically distinct isolates sampled from four wheat fields on three continents were assessed to determine the association of these two ecological parameters. Aggressiveness was assessed on two spring wheat cultivars (‘Toronit’ and ‘Greina’) in a greenhouse using percentages of leaf area covered by lesions and pycnidia. We found a positive correlation between aggressiveness of pathogen strains on the two cultivars, consistent with a quantitative and host-nonspecific interaction in this pathosystem. We also found a positive correlation between aggressiveness and average growth rate at two temperatures, suggesting that in vitro pathogen growth rate may make a significant contribution to pathogen aggressiveness.
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Affiliation(s)
- Fangfang Zhan
- First, second, third, and fourth authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China; fifth author: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, LFW, Zurich, CH-8092, Switzerland; and sixth author: Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou
| | - Yiekun Xie
- First, second, third, and fourth authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China; fifth author: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, LFW, Zurich, CH-8092, Switzerland; and sixth author: Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou
| | - Wen Zhu
- First, second, third, and fourth authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China; fifth author: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, LFW, Zurich, CH-8092, Switzerland; and sixth author: Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou
| | - Danli Sun
- First, second, third, and fourth authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China; fifth author: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, LFW, Zurich, CH-8092, Switzerland; and sixth author: Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou
| | - Bruce A. McDonald
- First, second, third, and fourth authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China; fifth author: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, LFW, Zurich, CH-8092, Switzerland; and sixth author: Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou
| | - Jiasui Zhan
- First, second, third, and fourth authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China; fifth author: Plant Pathology Group, Institute of Integrative Biology, ETH Zurich, LFW, Zurich, CH-8092, Switzerland; and sixth author: Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou
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Burdon JJ, Zhan J, Barrett LG, Papaïx J, Thrall PH. Addressing the Challenges of Pathogen Evolution on the World's Arable Crops. PHYTOPATHOLOGY 2016; 106:1117-1127. [PMID: 27584868 DOI: 10.1094/phyto-01-16-0036-fi] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Advances in genomic and molecular technologies coupled with an increasing understanding of the fine structure of many resistance and infectivity genes, have opened up a new era of hope in controlling the many plant pathogens that continue to be a major source of loss in arable crops. Some new approaches are under consideration including the use of nonhost resistance and the targeting of critical developmental constraints. However, the major thrust of these genomic and molecular approaches is to enhance the identification of resistance genes, to increase their ease of manipulation through marker and gene editing technologies and to lock a range of resistance genes together in simply manipulable resistance gene cassettes. All these approaches essentially continue a strategy that assumes the ability to construct genetic-based resistance barriers that are insurmountable to target pathogens. Here we show how the recent advances in knowledge and marker technologies can be used to generate more durable disease resistance strategies that are based on broad evolutionary principles aimed at presenting pathogens with a shifting, landscape of fluctuating directional selection.
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Affiliation(s)
- Jeremy J Burdon
- First and second authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology; Fujian Agriculture and Forestry University, Fuzhou, China; first, third, and fifth authors: CSIRO Agriculture, PO Box 1600, Canberra, A.C.T. 2601, Australia; and fourth author: INRA Biostatistics and Spatial Processes, Domaine Saint-Paul AgroParc, 84914 Avignon, France
| | - Jiasui Zhan
- First and second authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology; Fujian Agriculture and Forestry University, Fuzhou, China; first, third, and fifth authors: CSIRO Agriculture, PO Box 1600, Canberra, A.C.T. 2601, Australia; and fourth author: INRA Biostatistics and Spatial Processes, Domaine Saint-Paul AgroParc, 84914 Avignon, France
| | - Luke G Barrett
- First and second authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology; Fujian Agriculture and Forestry University, Fuzhou, China; first, third, and fifth authors: CSIRO Agriculture, PO Box 1600, Canberra, A.C.T. 2601, Australia; and fourth author: INRA Biostatistics and Spatial Processes, Domaine Saint-Paul AgroParc, 84914 Avignon, France
| | - Julien Papaïx
- First and second authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology; Fujian Agriculture and Forestry University, Fuzhou, China; first, third, and fifth authors: CSIRO Agriculture, PO Box 1600, Canberra, A.C.T. 2601, Australia; and fourth author: INRA Biostatistics and Spatial Processes, Domaine Saint-Paul AgroParc, 84914 Avignon, France
| | - Peter H Thrall
- First and second authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology; Fujian Agriculture and Forestry University, Fuzhou, China; first, third, and fifth authors: CSIRO Agriculture, PO Box 1600, Canberra, A.C.T. 2601, Australia; and fourth author: INRA Biostatistics and Spatial Processes, Domaine Saint-Paul AgroParc, 84914 Avignon, France
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Hagerty CH, Mundt CC. Reduced Virulence of Azoxystrobin-Resistant Zymoseptoria tritici Populations in Greenhouse Assays. PHYTOPATHOLOGY 2016; 106:884-889. [PMID: 27249373 DOI: 10.1094/phyto-01-16-0029-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The development of resistance to multiple fungicide classes is currently limiting disease management options for many pathogens, while the discovery of new fungicide classes may become less frequent. In light of this, more research is needed to quantify virulence trade-offs of fungicide resistance in order to more fully understand the implications of fungicide resistance on pathogen fitness. The purpose of this study was to measure the virulence of azoxystrobin-resistant and -sensitive Zymoseptoria tritici populations collected from North and South Willamette Valley, Oregon, in 2012 and 2015. Inoculum mixtures of known fungicide-resistant phenotypes were used to simulate natural field conditions, where multiple genotypes exist and interact in close proximity. Six greenhouse inoculations were conducted over 2 years, and virulence of the isolate mixtures was evaluated in planta. We considered virulence to be "the degree of pathology caused by the organism" and visually estimated the percent area of leaf necrosis as a measure of virulence. In greenhouse conditions, a consistent association of reduced virulence with azoxystrobin-resistant Z. tritici isolate mixtures was observed. North Willamette Valley and South Willamette Valley populations did not differ in virulence.
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Affiliation(s)
- Christina H Hagerty
- Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, 2701 SW Campus Way, Corvallis 97331
| | - Christopher C Mundt
- Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, 2701 SW Campus Way, Corvallis 97331
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Increased frequency of self-fertile isolates in Phytophthora infestans may attribute to their higher fitness relative to the A1 isolates. Sci Rep 2016; 6:29428. [PMID: 27384813 PMCID: PMC4935937 DOI: 10.1038/srep29428] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/17/2016] [Indexed: 01/01/2023] Open
Abstract
Knowledge of population dynamics of mating types is important for better understanding pathogen's evolutionary potential and sustainable management of natural and chemical resources such as host resistances and fungicides. In this study, 2250 Phytophthora infestans isolates sampled from 61 fields across China were assayed for spatiotemporal dynamics of mating type frequency. Self-fertile isolates dominated in ~50% of populations and all but one cropping region with an average frequency of 0.64 while no A2 isolates were detected. Analyses of 140 genotypes consisting of 82 self-fertile and 58 A1 isolates indicated that on average self-fertile isolates grew faster, demonstrated higher aggressiveness and were more tolerant to fungicides than A1 isolates; Furthermore, pattern of association between virulence complexity (defined as the number of differential cultivars on which an isolate can induce disease) and frequency was different in the two mating types. In A1 isolates, virulence complexity was negatively correlated (r = -0.515, p = 0.043) with frequency but this correlation was positive (r = 0.532, p = 0.037) in self-fertile isolates. Our results indicate a quick increase of self-fertile isolates possibly attributable to their higher fitness relative to A1 mating type counterpart in the field populations of P. infestans in China.
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Vaghefi N, Hay FS, Kikkert JR, Pethybridge SJ. Genotypic Diversity and Resistance to Azoxystrobin of Cercospora beticola on Processing Table Beet in New York. PLANT DISEASE 2016; 100:1466-1473. [PMID: 30686198 DOI: 10.1094/pdis-09-15-1014-re] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting productivity and profitability of beet production worldwide. Fungicides are critical for the control of this disease and one of the most commonly used products is the quinone outside inhibitor (QOI) azoxystrobin. In total, 150 C. beticola isolates were collected from two commercial processing table beet fields in Batavia, NY in 2014. The mating types of the entire population were determined, and genetic diversity of a subset of samples (n = 48) was assessed using five microsatellite loci. Sensitivity to azoxystrobin was tested using a spore germination assay. The cytochrome b gene was sequenced to check for the presence of point mutations known to confer QOI resistance in fungi. High allelic diversity (He = 0.50) and genotypic diversity (D* = 0.96), gametic equilibrium of the microsatellite loci, and equal ratios of mating types were suggestive of a mixed mode of reproduction for C. beticola. Resistance to azoxystrobin was prevalent because 41% of the isolates had values for effective concentrations reducing spore germination by 50% (EC50) > 0.2 μg/ml. The G143A mutation, known to cause QOI resistance in C. beticola, was found in isolates with EC50 values between 0.207 and 19.397 μg/ml. A single isolate with an EC50 of 0.272 μg/ml carried the F129L mutation, known to be associated with low levels of QOI resistance in fungi. This is the first report of the F129L mutation in C. beticola. The implications of these findings for the epidemiology and control of CLS in table beet fields in New York are discussed.
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Affiliation(s)
- Niloofar Vaghefi
- School of Integrative Plant Sciences, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456
| | - Frank S Hay
- School of Integrative Plant Sciences, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456
| | | | - Sarah J Pethybridge
- School of Integrative Plant Sciences, Plant Pathology & Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456
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Syller J, Grupa A. Antagonistic within-host interactions between plant viruses: molecular basis and impact on viral and host fitness. MOLECULAR PLANT PATHOLOGY 2016; 17:769-82. [PMID: 26416204 PMCID: PMC6638324 DOI: 10.1111/mpp.12322] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Double infections of related or unrelated viruses frequently occur in single plants, the viral agents being inoculated into the host plant simultaneously (co-infection) or sequentially (super-infection). Plants attacked by viruses activate sophisticated defence pathways which operate at different levels, often at significant fitness costs, resulting in yield reduction in crop plants. The occurrence and severity of the negative effects depend on the type of within-host interaction between the infecting viruses. Unrelated viruses generally interact with each other in a synergistic manner, whereas interactions between related viruses are mostly antagonistic. These can incur substantial fitness costs to one or both of the competitors. A relatively well-known antagonistic interaction is cross-protection, also referred to as super-infection exclusion. This type of interaction occurs when a previous infection with one virus prevents or interferes with subsequent infection by a homologous second virus. The current knowledge on why and how one virus variant excludes or restricts another is scant. Super-infection exclusion between viruses has predominantly been attributed to the induction of RNA silencing, which is a major antiviral defence mechanism in plants. There are, however, presumptions that various mechanisms are involved in this phenomenon. This review outlines the current state of knowledge concerning the molecular mechanisms behind antagonistic interactions between plant viruses. Harmful or beneficial effects of these interactions on viral and host plant fitness are also characterized. Moreover, the review briefly outlines the past and present attempts to utilize antagonistic interactions among viruses to protect crop plants against destructive diseases.
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Affiliation(s)
- Jerzy Syller
- Plant Breeding and Acclimatization Institute-National Research Institute, Laboratory of Phytopathology, Centre Młochów, 05-831, Młochów, Poland
| | - Anna Grupa
- Plant Breeding and Acclimatization Institute-National Research Institute, Laboratory of Phytopathology, Centre Młochów, 05-831, Młochów, Poland
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Wu EJ, Yang LN, Zhu W, Chen XM, Shang LP, Zhan J. Diverse mechanisms shape the evolution of virulence factors in the potato late blight pathogen Phytophthora infestans sampled from China. Sci Rep 2016; 6:26182. [PMID: 27193142 PMCID: PMC4872137 DOI: 10.1038/srep26182] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 04/27/2016] [Indexed: 01/23/2023] Open
Abstract
Evolution of virulence in plant pathogens is still poorly understood but the knowledge is important for the effective use of plant resistance and sustainable disease management. Spatial population dynamics of virulence, race and SSR markers in 140 genotypes sampled from seven geographic locations in China were compared to infer the mechanisms driving the evolution of virulence in Phytophthora infestans (P. infestans). All virulence types and a full spectrum of race complexity, ranging from the race able to infect the universally susceptible cultivar only to all differentials, were detected. Eight and two virulence factors were under diversifying and constraining selection respectively while no natural selection was detected in one of the virulence types. Further analyses revealed excesses in simple and complex races but deficiency in intermediate race and negative associations of annual mean temperature at the site from which pathogen isolates were collected with frequency of virulence to differentials and race complexity in the pathogen populations. These results suggest that host selection may interact with other factors such as climatic conditions in determining the evolutionary trajectory of virulence and race structure in P. infestans and global warming may slow down the emergence of new virulence in the pathogen.
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Affiliation(s)
- E-Jiao Wu
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
| | - Li-Na Yang
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
| | - Wen Zhu
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
| | - Xiao-Mei Chen
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
| | - Li-Ping Shang
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
| | - Jiasui Zhan
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P. R. China
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Weeds, as ancillary hosts, pose disproportionate risk for virulent pathogen transfer to crops. BMC Evol Biol 2016; 16:101. [PMID: 27176034 PMCID: PMC4866072 DOI: 10.1186/s12862-016-0680-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/06/2016] [Indexed: 11/11/2022] Open
Abstract
Background The outcome of the arms race between hosts and pathogens depends heavily on the interactions between their genetic diversity, population size and transmission ability. Theory predicts that genetically diverse hosts will select for higher virulence and more diverse pathogens than hosts with low genetic diversity. Cultivated hosts typically have lower genetic diversity and thus small effective population sizes, but can potentially harbour large pathogen population sizes. On the other hand, hosts, such as weeds, which are genetically more diverse and thus have larger effective population sizes, usually harbour smaller pathogen population sizes. Large pathogen population sizes may lead to more opportunities for mutation and hence more diverse pathogens. Here we test the predictions that pathogen neutral genetic diversity will increase with large pathogen population sizes and host diversity, whereas diversity under selection will increase with host diversity. We assessed and compared the diversity of a fungal pathogen, Rhynchosporium commune, on weedy barley grass (which have a large effective population size) and cultivated barley (low genetic diversity) using microsatellites, effector locus nip1 diversity and pathogen aggressiveness in order to assess the importance of weeds in the evolution of the neutral and selected diversity of pathogens. Results The findings indicated that the large barley acreage and low host diversity maintains higher pathogen neutral genetic diversity and lower linkage disequilibrium, while the weed maintains more pathotypes and higher virulence diversity at nip1. Strong evidence for more pathogen migration from barley grass to barley suggests transmission of virulence from barley grass to barley is common. Conclusions Pathogen census population size is a better predictor for neutral genetic diversity than host diversity. Despite maintaining a smaller pathogen census population size, barley grass acts as an important ancillary host to R. commune, harbouring highly virulent pathogen types capable of transmission to barley. Management of disease on crops must therefore include management of weedy ancillary hosts, which may harbour disproportionate supplies of virulent pathogen strains. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0680-6) contains supplementary material, which is available to authorized users.
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Delmas CEL, Fabre F, Jolivet J, Mazet ID, Richart Cervera S, Delière L, Delmotte F. Adaptation of a plant pathogen to partial host resistance: selection for greater aggressiveness in grapevine downy mildew. Evol Appl 2016; 9:709-25. [PMID: 27247621 PMCID: PMC4869412 DOI: 10.1111/eva.12368] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 01/27/2016] [Indexed: 01/29/2023] Open
Abstract
An understanding of the evolution of pathogen quantitative traits in response to host selective pressures is essential for the development of durable management strategies for resistant crops. However, we still lack experimental data on the effects of partial host resistance on multiple phenotypic traits (aggressiveness) and evolutionary strategies in pathogens. We performed a cross‐inoculation experiment with four grapevine hosts and 103 isolates of grapevine downy mildew (Plasmopara viticola) sampled from susceptible and partially resistant grapevine varieties. We analysed the neutral and adaptive genetic differentiation of five quantitative traits relating to pathogen transmission. Isolates from resistant hosts were more aggressive than isolates from susceptible hosts, as they had a shorter latency period and higher levels of spore production. This pattern of adaptation contrasted with the lack of neutral genetic differentiation, providing evidence for directional selection. No specificity for a particular host variety was detected. Adapted isolates had traits that were advantageous on all resistant varieties. There was no fitness cost associated with this genetic adaptation, but several trade‐offs between pathogen traits were observed. These results should improve the accuracy of prediction of fitness trajectories for this biotrophic pathogen, an essential element for the modelling of durable deployment strategies for resistant varieties.
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Affiliation(s)
- Chloé E L Delmas
- UMR 1065 Santé et Agroécologie du VignobleINRAVillenave d'OrnonFrance; Bordeaux Science AgroUMR 1065 SAVEISVVUniversité de BordeauxVillenave d'OrnonFrance
| | - Frédéric Fabre
- UMR 1065 Santé et Agroécologie du VignobleINRAVillenave d'OrnonFrance; Bordeaux Science AgroUMR 1065 SAVEISVVUniversité de BordeauxVillenave d'OrnonFrance
| | - Jérôme Jolivet
- UMR 1065 Santé et Agroécologie du VignobleINRAVillenave d'OrnonFrance; Bordeaux Science AgroUMR 1065 SAVEISVVUniversité de BordeauxVillenave d'OrnonFrance
| | - Isabelle D Mazet
- UMR 1065 Santé et Agroécologie du VignobleINRAVillenave d'OrnonFrance; Bordeaux Science AgroUMR 1065 SAVEISVVUniversité de BordeauxVillenave d'OrnonFrance
| | - Sylvie Richart Cervera
- UMR 1065 Santé et Agroécologie du VignobleINRAVillenave d'OrnonFrance; Bordeaux Science AgroUMR 1065 SAVEISVVUniversité de BordeauxVillenave d'OrnonFrance
| | - Laurent Delière
- UMR 1065 Santé et Agroécologie du VignobleINRAVillenave d'OrnonFrance; Bordeaux Science AgroUMR 1065 SAVEISVVUniversité de BordeauxVillenave d'OrnonFrance
| | - François Delmotte
- UMR 1065 Santé et Agroécologie du VignobleINRAVillenave d'OrnonFrance; Bordeaux Science AgroUMR 1065 SAVEISVVUniversité de BordeauxVillenave d'OrnonFrance
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