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Comparative Analysis of Tomato Brown Rugose Fruit Virus Isolates Shows Limited Genetic Diversity. Viruses 2022; 14:v14122816. [PMID: 36560820 PMCID: PMC9784425 DOI: 10.3390/v14122816] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/13/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Tomato is an important vegetable in the United States and around the world. Recently, tomato brown rugose fruit virus (ToBRFV), an emerging tobamovirus, has impacted tomato crops worldwide and can result in fruit loss. ToBRFV causes severe symptoms, such as mosaic, puckering, and necrotic lesions on leaves; other symptoms include brown rugose and marbling on fruits. More importantly, ToBRFV can overcome resistance in tomato cultivars carrying the Tm-22 locus. In this study, we recovered ToBRFV sequences from tomato seeds, leaves, and fruits from the U.S., Mexico, and Peru. Samples were pre-screened using a real-time RT-PCR assay prior to high-throughput sequencing. Virus draft genomes from 22 samples were assembled and analyzed against more than 120 publicly available genomes. Overall, most sequenced isolates were similar to each other and did not form a distinct population. Phylogenetic analysis revealed three clades within the ToBRFV population. Most of the isolates (95%) clustered in clade 3. Genetic analysis revealed differentiation between the three clades indicating minor divergence occurring. Overall, pairwise identity showed limited genetic diversity among the isolates in this study with worldwide isolates, with a pairwise identity ranging from 99.36% and 99.97%. The overall population is undergoing high gene flow and population expansion with strong negative selection pressure at all ToBRFV genes. Based on the results of this study, it is likely that the limited ToBRFV diversity is associated with the rapid movement and eradication of ToBRFV-infected material between countries.
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2
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Saubin M, Louet C, Bousset L, Fabre F, Frey P, Fudal I, Grognard F, Hamelin F, Mailleret L, Stoeckel S, Touzeau S, Petre B, Halkett F. Improving sustainable crop protection using population genetics concepts. Mol Ecol 2022; 32:2461-2471. [PMID: 35906846 DOI: 10.1111/mec.16634] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 10/16/2022]
Abstract
Growing genetically resistant plants allows pathogen populations to be controlled and reduces the use of pesticides. However, pathogens can quickly overcome such resistance. In this context, how can we achieve sustainable crop protection? This crucial question has remained largely unanswered despite decades of intense debate and research effort. In this study, we used a bibliographic analysis to show that the research field of resistance durability has evolved into three subfields: (i) 'plant breeding' (generating new genetic material), (ii) 'molecular interactions' (exploring the molecular dialogue governing plant-pathogen interactions) and (iii) 'epidemiology and evolution' (explaining and forecasting of pathogen population dynamics resulting from selection pressure(s) exerted by resistant plants). We argue that this triple split of the field impedes integrated research progress and ultimately compromises the sustainable management of genetic resistance. After identifying a gap among the three subfields, we argue that the theoretical framework of population genetics could bridge this gap. Indeed, population genetics formally explains the evolution of all heritable traits, and allows genetic changes to be tracked along with variation in population dynamics. This provides an integrated view of pathogen adaptation, in particular via evolutionary-epidemiological feedbacks. In this Opinion Note, we detail examples illustrating how such a framework can better inform best practices for developing and managing genetically resistant cultivars.
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Affiliation(s)
| | - Clémentine Louet
- Université de Lorraine, INRAE, IAM, Nancy, France.,Université Paris Saclay, INRAE, BIOGER, Thiverval-Grignon, France
| | - Lydia Bousset
- INRAE, Agrocampus Ouest, Université de Rennes, IGEPP, Le Rheu, France
| | - Frédéric Fabre
- INRAE, Bordeaux Sciences Agro, SAVE, F-33882 Villenave d'Ornon, France
| | - Pascal Frey
- Université de Lorraine, INRAE, IAM, Nancy, France
| | - Isabelle Fudal
- Université Paris Saclay, INRAE, BIOGER, Thiverval-Grignon, France
| | - Frédéric Grognard
- Université Côte d'Azur, Inria, INRAE, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France
| | - Frédéric Hamelin
- INRAE, Agrocampus Ouest, Université de Rennes, IGEPP, Le Rheu, France
| | - Ludovic Mailleret
- Université Côte d'Azur, Inria, INRAE, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France.,Université Côte d'Azur, INRAE, CNRS, ISA, Sophia Antipolis, France
| | - Solenn Stoeckel
- INRAE, Agrocampus Ouest, Université de Rennes, IGEPP, Le Rheu, France
| | - Suzanne Touzeau
- Université Côte d'Azur, Inria, INRAE, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France
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Lauer E, Isik F. Major QTL confer race-nonspecific resistance in the co-evolved Cronartium quercuum f. sp. fusiforme-Pinus taeda pathosystem. Heredity (Edinb) 2021; 127:288-299. [PMID: 34172936 PMCID: PMC8405641 DOI: 10.1038/s41437-021-00451-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
Fusiform rust disease, caused by the endemic fungus Cronartium quercuum f. sp. fusiforme, is the most damaging disease affecting economically important pine species in the southeast United States. Unlike the major epidemics of agricultural crops, the co-evolved pine-rust pathosystem is characterized by steady-state dynamics and high levels of genetic diversity within environments. This poses a unique challenge and opportunity for the deployment of large-effect resistance genes. We used trait dissection to study the genetic architecture of disease resistance in two P. taeda parents that showed high resistance across multiple environments. Two mapping populations (full-sib families), each with ~1000 progeny, were challenged with a complex inoculum consisting of 150 pathogen isolates. High-density linkage mapping revealed three major-effect QTL distributed on two linkage groups. All three QTL were validated using a population of 2057 cloned pine genotypes in a 6-year-old multi-environmental field trial. As a complement to the QTL mapping approach, bulked segregant RNAseq analysis revealed a small number of candidate nucleotide binding leucine-rich repeat genes harboring SNP associated with disease resistance. The results of this study show that in P. taeda, a small number of major QTL can provide effective resistance against genetically diverse mixtures of an endemic pathogen. These QTL vary in their impact on disease liability and exhibit additivity in combination.
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Affiliation(s)
- Edwin Lauer
- grid.40803.3f0000 0001 2173 6074North Carolina State University, Raleigh, NC USA
| | - Fikret Isik
- grid.40803.3f0000 0001 2173 6074North Carolina State University, Raleigh, NC USA
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4
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Rimbaud L, Fabre F, Papaïx J, Moury B, Lannou C, Barrett LG, Thrall PH. Models of Plant Resistance Deployment. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:125-152. [PMID: 33929880 DOI: 10.1146/annurev-phyto-020620-122134] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Owing to their evolutionary potential, plant pathogens are able to rapidly adapt to genetically controlled plant resistance, often resulting in resistance breakdown and major epidemics in agricultural crops. Various deployment strategies have been proposed to improve resistance management. Globally, these rely on careful selection of resistance sources and their combination at various spatiotemporal scales (e.g., via gene pyramiding, crop rotations and mixtures, landscape mosaics). However, testing and optimizing these strategies using controlled experiments at large spatiotemporal scales are logistically challenging. Mathematical models provide an alternative investigative tool, and many have been developed to explore resistance deployment strategies under various contexts. This review analyzes 69 modeling studies in light of specific model structures (e.g., demographic or demogenetic, spatial or not), underlying assumptions (e.g., whether preadapted pathogens are present before resistance deployment), and evaluation criteria (e.g., resistance durability, disease control, cost-effectiveness). It highlights major research findings and discusses challenges for future modeling efforts.
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Affiliation(s)
- Loup Rimbaud
- INRAE, Pathologie Végétale, 84140 Montfavet, France; ,
- CSIRO Agriculture and Food, Canberra, ACT 2601, Australia; ,
| | - Frédéric Fabre
- INRAE, Bordeaux Sciences Agro, SAVE, 33882 Villenave d'Ornon, France;
| | | | - Benoît Moury
- INRAE, Pathologie Végétale, 84140 Montfavet, France; ,
| | | | - Luke G Barrett
- CSIRO Agriculture and Food, Canberra, ACT 2601, Australia; ,
| | - Peter H Thrall
- CSIRO Agriculture and Food, Canberra, ACT 2601, Australia; ,
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5
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Heo KJ, Kwon SJ, Kim MK, Kwak HR, Han SJ, Kwon MJ, Rao ALN, Seo JK. Newly emerged resistance-breaking variants of cucumber mosaic virus represent ongoing host-interactive evolution of an RNA virus. Virus Evol 2020; 6:veaa070. [PMID: 33240527 PMCID: PMC7673075 DOI: 10.1093/ve/veaa070] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Understanding the evolutionary history of a virus and the mechanisms influencing the direction of its evolution is essential for the development of more durable strategies to control the virus in crop fields. While the deployment of host resistance in crops is the most efficient means to control various viruses, host resistance itself can act as strong selective pressure and thus play a critical role in the evolution of virus virulence. Cucumber mosaic virus (CMV), a plant RNA virus with high evolutionary capacity, has caused endemic disease in various crops worldwide, including pepper (Capsicum annuum L.), because of frequent emergence of resistance-breaking variants. In this study, we examined the molecular and evolutionary characteristics of recently emerged, resistance-breaking CMV variants infecting pepper. Our population genetics analysis revealed that the high divergence capacity of CMV RNA1 might have played an essential role in the host-interactive evolution of CMV and in shaping the CMV population structure in pepper. We also demonstrated that nonsynonymous mutations in RNA1 encoding the 1a protein enabled CMV to overcome the deployed resistance in pepper. Our findings suggest that resistance-driven selective pressures on RNA1 might have contributed in shaping the unique evolutionary pattern of CMV in pepper. Therefore, deployment of a single resistance gene may reduce resistance durability against CMV and more integrated approaches are warranted for successful control of CMV in pepper.
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Affiliation(s)
| | - Sun-Jung Kwon
- Institutes of Green Bio Science and Technology, Seoul National University, 1447 Pyeongchang-ro, Pyeongchang 25354, Republic of Korea
| | - Mi-Kyeong Kim
- Department of Plant Medicine, Chungbuk National University, 1 Chungdae-ro, Cheongju 28644, Republic of Korea
| | - Hae-Ryun Kwak
- Crop Protection Division, National Institute of Agricultural Sciences, Rural Development Administration, 300 Nongsaengmyeong-ro, Wanju 55365, Republic of Korea
| | - Soo-Jung Han
- Department of International Agricultural Technology
| | - Min-Jun Kwon
- Department of International Agricultural Technology
| | - A L N Rao
- Department of Microbiology and Plant Pathology, University of California, Boyce Hall 1463, 900 University Ave, Riverside, CA 92521, USA
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6
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Random Mutagenesis of Virus Gene for the Experimental Evaluation of the Durability of NB-LRR Class Plant Virus Resistance Gene. Methods Mol Biol 2020. [PMID: 31228110 DOI: 10.1007/978-1-4939-9635-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
NB-LRR class plant virus resistance gene is a one of the key players that shape the plant-virus interaction. Evolutionary arms race between plants and viruses often results in the breakdown of virus resistance in plants, which leads to a disastrous outcome in agricultural production. Although studies have analyzed the nature of plant virus resistance breakdown, it is still difficult to foresee the breakdown of a given virus resistance gene. In this chapter, we provide a protocol for evaluating the durability of plant virus resistance gene, which comprises the random mutagenesis of a virus gene, the introduction of the mutagenized gene into a virus context with highly efficient inoculation system, and the efficient screening of virus mutants that can overcome or escape a virus resistance.
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7
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The RNA-Dependent RNA Polymerase NIb of Potyviruses Plays Multifunctional, Contrasting Roles during Viral Infection. Viruses 2020; 12:v12010077. [PMID: 31936267 PMCID: PMC7019339 DOI: 10.3390/v12010077] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/28/2019] [Accepted: 01/03/2020] [Indexed: 12/14/2022] Open
Abstract
Potyviruses represent the largest group of known plant RNA viruses and include many agriculturally important viruses, such as Plum pox virus, Soybean mosaic virus, Turnip mosaic virus, and Potato virus Y. Potyviruses adopt polyprotein processing as their genome expression strategy. Among the 11 known viral proteins, the nuclear inclusion protein b (NIb) is the RNA-dependent RNA polymerase responsible for viral genome replication. Beyond its principal role as an RNA replicase, NIb has been shown to play key roles in diverse virus–host interactions. NIb recruits several host proteins into the viral replication complexes (VRCs), which are essential for the formation of functional VRCs for virus multiplication, and interacts with the sumoylation pathway proteins to suppress NPR1-mediated immunity response. On the other hand, NIb serves as a target of selective autophagy as well as an elicitor of effector-triggered immunity, resulting in attenuated virus infection. These contrasting roles of NIb provide an excellent example of the complex co-evolutionary arms race between plant hosts and potyviruses. This review highlights the current knowledge about the multifunctional roles of NIb in potyvirus infection, and discusses future research directions.
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8
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Weiland JJ, Bornemann K, Neubauer JD, Khan MFR, Bolton MD. Prevalence and Distribution of Beet Necrotic Yellow Vein Virus Strains in North Dakota and Minnesota. PLANT DISEASE 2019; 103:2083-2089. [PMID: 31210599 DOI: 10.1094/pdis-02-19-0360-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Beet necrotic yellow vein virus (BNYVV) is the causal agent of rhizomania, a disease of global importance to the sugar beet industry. The most widely implemented resistance gene to rhizomania to date is Rz1, but resistance has been circumvented by resistance-breaking (RB) isolates worldwide. In an effort to gain greater understanding of the distribution of BNYVV and the nature of RB isolates in Minnesota and eastern North Dakota, sugar beet plants were grown in 594 soil samples obtained from production fields and subsequently were analyzed for the presence of BNYVV as well as coding variability in the viral P25 gene, the gene previously implicated in the RB pathotype. Baiting of virus from the soil with sugar beet varieties possessing no known resistance to rhizomania resulted in a disease incidence level of 10.6% in the region examined. Parallel baiting analysis of sugar beet genotypes possessing Rz1, the more recently introgressed Rz2, and with the combination of Rz1 + Rz2 resulted in a disease incidence level of 4.2, 1.0, and 0.8%, respectively. Virus sequences recovered from sugar beet bait plants possessing resistance genes Rz1 and/or Rz2 exhibited reduced genetic diversity in the P25 gene relative to those recovered from the susceptible genotype while confirming the hypervariable nature of the coding for amino acids (AAs) at position 67 and 68 in the P25 protein. In contrast to previous reports, we did not find an association between any one specific AA signature at these positions and the ability to circumvent Rz1-mediated resistance. The data document ongoing virulence development in BNYVV populations to previously resistant varieties and provide a baseline for the analysis of genetic change in the virus population that may accompany the implementation of new resistance genes to manage rhizomania.
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Affiliation(s)
- John J Weiland
- 1United States Department of Agriculture - Agricultural Research Service, Edward T. Schafer Agricultural Research Center, Fargo, ND
| | - Kathrin Bornemann
- 1United States Department of Agriculture - Agricultural Research Service, Edward T. Schafer Agricultural Research Center, Fargo, ND
- 2Department of Plant Pathology, North Dakota State University, Fargo, ND
| | - Jonathan D Neubauer
- 1United States Department of Agriculture - Agricultural Research Service, Edward T. Schafer Agricultural Research Center, Fargo, ND
| | - Mohamed F R Khan
- 2Department of Plant Pathology, North Dakota State University, Fargo, ND
- 3Department of Plant Pathology, University of Minnesota, St. Paul, MN
| | - Melvin D Bolton
- 1United States Department of Agriculture - Agricultural Research Service, Edward T. Schafer Agricultural Research Center, Fargo, ND
- 2Department of Plant Pathology, North Dakota State University, Fargo, ND
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9
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Charon J, Barra A, Walter J, Millot P, Hébrard E, Moury B, Michon T. First Experimental Assessment of Protein Intrinsic Disorder Involvement in an RNA Virus Natural Adaptive Process. Mol Biol Evol 2019; 35:38-49. [PMID: 29029259 PMCID: PMC5850501 DOI: 10.1093/molbev/msx249] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Intrinsic disorder (ID) in proteins is defined as a lack of stable structure in physiological conditions. Intrinsically disordered regions (IDRs) are highly abundant in some RNA virus proteomes. Low topological constraints exerted on IDRs are expected to buffer the effect of numerous deleterious mutations and could be related to the remarkable adaptive potential of RNA viruses to overcome resistance of their host. To experimentally test this hypothesis in a natural pathosystem, a set of four variants of Potato virus Y (PVY; Potyvirus genus) containing various ID degrees in the Viral genome-linked (VPg) protein, a key determinant of potyvirus adaptation, was designed. To estimate the ID contribution to the VPg-based PVY adaptation, the adaptive ability of the four PVY variants was monitored in the pepper host (Capsicum annuum) carrying a recessive resistance gene. Intriguingly, the two mutants with the highest ID content displayed a significantly higher ability to restore infection in the resistant host, whereas the less intrinsically disordered mutant was unable to restore infection. The role of ID on virus adaptation may be due either to a larger exploration of evolutionary pathways or the minimization of fitness penalty caused by resistance-breaking mutations. This pioneering study strongly suggests the positive impact of ID in an RNA virus adaptive capacity.
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Affiliation(s)
- Justine Charon
- UMR Biologie du Fruit et Pathologie, INRA, Université de Bordeaux, Villenave d'Ornon, France.,CNRS 5320, INSERM U1212, Pessac, France
| | - Amandine Barra
- UMR Biologie du Fruit et Pathologie, INRA, Université de Bordeaux, Villenave d'Ornon, France
| | - Jocelyne Walter
- UMR Biologie du Fruit et Pathologie, INRA, Université de Bordeaux, Villenave d'Ornon, France
| | | | - Eugénie Hébrard
- UMR Interactions Plantes-Microorganismes-Environnement, IRD, CIRAD, Université de Montpellier, Montpellier, France
| | | | - Thierry Michon
- UMR Biologie du Fruit et Pathologie, INRA, Université de Bordeaux, Villenave d'Ornon, France
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10
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Chisholm PJ, Busch JW, Crowder DW. Effects of life history and ecology on virus evolutionary potential. Virus Res 2019; 265:1-9. [PMID: 30831177 DOI: 10.1016/j.virusres.2019.02.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 11/28/2022]
Abstract
The life history traits of viruses pose many consequences for viral population structure. In turn, population structure may influence the evolutionary trajectory of a virus. Here we review factors that affect the evolutionary potential of viruses, including rates of mutation and recombination, bottlenecks, selection pressure, and ecological factors such as the requirement for hosts and vectors. Mutation, while supplying a pool of raw genetic material, also results in the generation of numerous unfit mutants. The infection of multiple host species may expand a virus' ecological niche, although it may come at a cost to genetic diversity. Vector-borne viruses often experience a diminished frequency of positive selection and exhibit little diversity, and resistance against vector-borne viruses may thus be more durable than against non-vectored viruses. Evidence indicates that adaptation to a vector is more evolutionarily difficult than adaptation to a host. Overall, a better understanding of how various factors influence viral dynamics in both plant and animal pathosystems will lead to more effective anti-viral treatments and countermeasures.
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Affiliation(s)
- Paul J Chisholm
- Department of Entomology, Washington State University, 166 FSHN Building, Pullman, WA, 99164, USA.
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164, USA.
| | - David W Crowder
- Department of Entomology, Washington State University, 166 FSHN Building, Pullman, WA, 99164, USA.
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11
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Rousseau E, Tamisier L, Fabre F, Simon V, Szadkowski M, Bouchez O, Zanchetta C, Girardot G, Mailleret L, Grognard F, Palloix A, Moury B. Impact of genetic drift, selection and accumulation level on virus adaptation to its host plants. MOLECULAR PLANT PATHOLOGY 2018; 19:2575-2589. [PMID: 30074299 PMCID: PMC6638063 DOI: 10.1111/mpp.12730] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The efficiency of plant major resistance genes is limited by the emergence and spread of resistance-breaking mutants. Modulation of the evolutionary forces acting on pathogen populations constitutes a promising way to increase the durability of these genes. We studied the effect of four plant traits affecting these evolutionary forces on the rate of resistance breakdown (RB) by a virus. Two of these traits correspond to virus effective population sizes (Ne ) at either plant inoculation or during infection. The third trait corresponds to differential selection exerted by the plant on the virus population. Finally, the fourth trait corresponds to within-plant virus accumulation (VA). These traits were measured experimentally on Potato virus Y (PVY) inoculated to a set of 84 pepper doubled-haploid lines, all carrying the same pvr23 resistance gene, but having contrasting genetic backgrounds. The lines showed extensive variation for the rate of pvr23 RB by PVY and for the four other traits of interest. A generalized linear model showed that three of these four traits, with the exception of Ne at inoculation, and several pairwise interactions between them had significant effects on RB. RB increased with increasing values of Ne during plant infection or VA. The effect of differential selection was more complex because of a strong interaction with VA. When VA was high, RB increased as the differential selection increased. An opposite relationship between RB and differential selection was observed when VA was low. This study provides a framework to select plants with appropriate virus evolution-related traits to avoid or delay RB.
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Affiliation(s)
- Elsa Rousseau
- Pathologie VégétaleINRA84140MontfavetFrance
- Université Côte d'Azur, Inria, INRA, CNRS, Sorbonne UniversitéBiocore TeamSophia AntipolisFrance
- Université Côte d'Azur, INRA, CNRS, ISAFrance
- Present address:
IBM Almaden Research CenterSan Jose, CA 95120–6099USA
| | - Lucie Tamisier
- Pathologie VégétaleINRA84140MontfavetFrance
- GAFL, INRA84140MontfavetFrance
- Present address:
Université de Liège, Terra‐Gembloux Agro-Bio Tech, PlantPathology Laboratory, Passage des Déportés2, GemblouxBelgium, 5030
| | | | - Vincent Simon
- Pathologie VégétaleINRA84140MontfavetFrance
- UMR BFPINRA33882Villenave d'OrnonFrance
| | | | - Olivier Bouchez
- INRAGeT‐PlaGe, US 1426, Genotoul, 31326 Castanet‐TolosanFrance
| | | | | | - Ludovic Mailleret
- Université Côte d'Azur, Inria, INRA, CNRS, Sorbonne UniversitéBiocore TeamSophia AntipolisFrance
- Université Côte d'Azur, INRA, CNRS, ISAFrance
| | - Frederic Grognard
- Université Côte d'Azur, Inria, INRA, CNRS, Sorbonne UniversitéBiocore TeamSophia AntipolisFrance
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12
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Role of the Genetic Background in Resistance to Plant Viruses. Int J Mol Sci 2018; 19:ijms19102856. [PMID: 30241370 PMCID: PMC6213453 DOI: 10.3390/ijms19102856] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/10/2018] [Accepted: 09/11/2018] [Indexed: 01/03/2023] Open
Abstract
In view of major economic problems caused by viruses, the development of genetically resistant crops is critical for breeders but remains limited by the evolution of resistance-breaking virus mutants. During the plant breeding process, the introgression of traits from Crop Wild Relatives results in a dramatic change of the genetic background that can alter the resistance efficiency or durability. Here, we conducted a meta-analysis on 19 Quantitative Trait Locus (QTL) studies of resistance to viruses in plants. Frequent epistatic effects between resistance genes indicate that a large part of the resistance phenotype, conferred by a given QTL, depends on the genetic background. We next reviewed the different resistance mechanisms in plants to survey at which stage the genetic background could impact resistance or durability. We propose that the genetic background may impair effector-triggered dominant resistances at several stages by tinkering the NB-LRR (Nucleotide Binding-Leucine-Rich Repeats) response pathway. In contrast, effects on recessive resistances by loss-of-susceptibility-such as eIF4E-based resistances-are more likely to rely on gene redundancy among the multigene family of host susceptibility factors. Finally, we show how the genetic background is likely to shape the evolution of resistance-breaking isolates and propose how to take this into account in order to breed plants with increased resistance durability to viruses.
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13
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Pagán I. The diversity, evolution and epidemiology of plant viruses: A phylogenetic view. INFECTION GENETICS AND EVOLUTION 2018; 65:187-199. [PMID: 30055330 DOI: 10.1016/j.meegid.2018.07.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/24/2018] [Accepted: 07/24/2018] [Indexed: 10/28/2022]
Abstract
During the past four decades, the scientific community has seen an exponential advance in the number, sophistication, and quality of molecular techniques and bioinformatics tools for the genetic characterization of plant virus populations. Predating these advances, the field of Phylogenetics has significantly contributed to understand important aspects of plant virus evolution. This review aims at summarizing the impact of Phylogenetics in the current knowledge on three major aspects of plant virus evolution that have benefited from the development of phylogenetic inference: (1) The identification and classification of plant virus diversity. (2) The mechanisms and forces shaping the evolution of plant virus populations. (3) The understanding of the interaction between plant virus evolution, epidemiology and ecology. The work discussed here highlights the important role of phylogenetic approaches in the study of the dynamics of plant virus populations.
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Affiliation(s)
- Israel Pagán
- Centro de Biotecnología y Genómica de Plantas UPM-INIA, E.T.S. Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid 28223, Spain.
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Eoche-Bosy D, Gautier M, Esquibet M, Legeai F, Bretaudeau A, Bouchez O, Fournet S, Grenier E, Montarry J. Genome scans on experimentally evolved populations reveal candidate regions for adaptation to plant resistance in the potato cyst nematode Globodera pallida. Mol Ecol 2017; 26:4700-4711. [PMID: 28734070 DOI: 10.1111/mec.14240] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/13/2017] [Accepted: 07/17/2017] [Indexed: 12/30/2022]
Abstract
Improving resistance durability involves to be able to predict the adaptation speed of pathogen populations. Identifying the genetic bases of pathogen adaptation to plant resistances is a useful step to better understand and anticipate this phenomenon. Globodera pallida is a major pest of potato crop for which a resistance QTL, GpaVvrn , has been identified in Solanum vernei. However, its durability is threatened as G. pallida populations are able to adapt to the resistance in few generations. The aim of this study was to investigate the genomic regions involved in the resistance breakdown by coupling experimental evolution and high-density genome scan. We performed a whole-genome resequencing of pools of individuals (Pool-Seq) belonging to G. pallida lineages derived from two independent populations having experimentally evolved on susceptible and resistant potato cultivars. About 1.6 million SNPs were used to perform the genome scan using a recent model testing for adaptive differentiation and association to population-specific covariables. We identified 275 outliers and 31 of them, which also showed a significant reduction in diversity in adapted lineages, were investigated for their genic environment. Some candidate genomic regions contained genes putatively encoding effectors and were enriched in SPRYSECs, known in cyst nematodes to be involved in pathogenicity and in (a)virulence. Validated candidate SNPs will provide a useful molecular tool to follow frequencies of virulence alleles in natural G. pallida populations and define efficient strategies of use of potato resistances maximizing their durability.
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Affiliation(s)
- D Eoche-Bosy
- IGEPP, INRA, Agrocampus Ouest, Université de Rennes 1, Le Rheu, France
| | - M Gautier
- CBGP, INRA, IRD, CIRAD, Montpellier SupAgro, Montferrier-sur-Lez, France.,IBC, Montpellier, France
| | - M Esquibet
- IGEPP, INRA, Agrocampus Ouest, Université de Rennes 1, Le Rheu, France
| | - F Legeai
- IGEPP, BIPAA, INRA, Agrocampus Ouest, Université de Rennes 1, Rennes, France.,IRISA, GenScale, INRIA, Rennes, France
| | - A Bretaudeau
- IGEPP, BIPAA, INRA, Agrocampus Ouest, Université de Rennes 1, Rennes, France.,IRISA, GenOuest COre Facility, INRIA, Rennes, France
| | - O Bouchez
- GeT-PlaGe, Genotoul, INRA, Castanet-Tolosan, France.,GenPhySE, Université de Toulouse, INRA, INPT, ENVT, Castanet-Tolosan, France
| | - S Fournet
- IGEPP, INRA, Agrocampus Ouest, Université de Rennes 1, Le Rheu, France
| | - E Grenier
- IGEPP, INRA, Agrocampus Ouest, Université de Rennes 1, Le Rheu, France
| | - J Montarry
- IGEPP, INRA, Agrocampus Ouest, Université de Rennes 1, Le Rheu, France
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15
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Pinel-Galzi A, Dubreuil-Tranchant C, Hébrard E, Mariac C, Ghesquière A, Albar L. Mutations in Rice yellow mottle virus Polyprotein P2a Involved in RYMV2 Gene Resistance Breakdown. FRONTIERS IN PLANT SCIENCE 2016; 7:1779. [PMID: 27965688 PMCID: PMC5125353 DOI: 10.3389/fpls.2016.01779] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/11/2016] [Indexed: 05/09/2023]
Abstract
Rice yellow mottle virus (RYMV) is one of the major diseases of rice in Africa. The high resistance of the Oryza glaberrima Tog7291 accession involves a null allele of the RYMV2 gene, whose ortholog in Arabidopsis, CPR5, is a transmembrane nucleoporin involved in effector-triggered immunity. To optimize field deployment of the RYMV2 gene and improve its durability, which is often a weak point in varietal resistance, we analyzed its efficiency toward RYMV isolates representing the genetic diversity of the virus and the molecular basis of resistance breakdown. Tog7291 resistance efficiency was highly variable depending on the isolate used, with infection rates ranging from 0 to 98% of plants. Back-inoculation experiments indicated that infection cases were not due to an incomplete resistance phenotype but to the emergence of resistance-breaking (RB) variants. Interestingly, the capacity of the virus to overcome Tog7291 resistance is associated with a polymorphism at amino-acid 49 of the VPg protein which also affects capacity to overcome the previously studied RYMV1 resistance gene. This polymorphism appeared to be a main determinant of the emergence of RB variants. It acts independently of the resistance gene and rather reflects inter-species adaptation with potential consequences for the durability of resistance. RB mutations were identified by full-length or partial sequencing of the RYMV genome in infected Tog7291 plants and were validated by directed mutagenesis of an infectious viral clone. We found that Tog7291 resistance breakdown involved mutations in the putative membrane anchor domain of the polyprotein P2a. Although the precise effect of these mutations on rice/RYMV interaction is still unknown, our results offer a new perspective for the understanding of RYMV2 mediated resistance mechanisms. Interestingly, in the susceptible IR64 variety, RB variants showed low infectivity and frequent reversion to the wild-type genotype, suggesting that Tog7291 resistance breakdown is associated with a major loss of viral fitness in normally susceptible O. sativa varieties. Despite the high frequency of resistance breakdown in controlled conditions, this loss of fitness is an encouraging element with regards to RYMV2 resistance durability.
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Affiliation(s)
- Agnès Pinel-Galzi
- Interactions Plantes Microorganismes Environnement, Institut de Recherche pour le Développement – Centre de Coopération Internationale en Recherche Agronomique pour le Développement – Université de MontpellierMontpellier, France
| | - Christine Dubreuil-Tranchant
- Plant Diversity Adaptation and Development Research Unit, Institut de Recherche pour le Développement – Université de MontpellierMontpellier, France
| | - Eugénie Hébrard
- Interactions Plantes Microorganismes Environnement, Institut de Recherche pour le Développement – Centre de Coopération Internationale en Recherche Agronomique pour le Développement – Université de MontpellierMontpellier, France
| | - Cédric Mariac
- Plant Diversity Adaptation and Development Research Unit, Institut de Recherche pour le Développement – Université de MontpellierMontpellier, France
| | - Alain Ghesquière
- Plant Diversity Adaptation and Development Research Unit, Institut de Recherche pour le Développement – Université de MontpellierMontpellier, France
| | - Laurence Albar
- Plant Diversity Adaptation and Development Research Unit, Institut de Recherche pour le Développement – Université de MontpellierMontpellier, France
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16
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Wang Y, Hajimorad MR. Gain of virulence by Soybean mosaic virus on Rsv4-genotype soybeans is associated with a relative fitness loss in a susceptible host. MOLECULAR PLANT PATHOLOGY 2016; 17:1154-9. [PMID: 26662495 PMCID: PMC6638382 DOI: 10.1111/mpp.12354] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
'Gene-for-gene' theory predicts that gain of virulence by an avirulent pathogen on plants expressing resistance (R) genes is associated with fitness loss in susceptible hosts. However, the validity of this prediction has been studied in only a few plant viral pathosystems. In this study, the Soybean mosaic virus (SMV)-Rsv4 pathosystem was exploited to test this prediction. In Rsv4-genotype soybeans, P3 of avirulent SMV strains provokes an as yet uncharacterized resistance mechanism that restricts the invading virus to the inoculated leaves. A single amino acid substitution in P3 functionally converts an avirulent to a virulent strain, suggesting that the genetic composition of P3 plays a crucial role in virulence on Rsv4-genotype soybeans. In this study, we examined the impact of gain of virulence mutation(s) on the fitness of virulent variants derived from three avirulent SMV strains in a soybean genotype lacking the Rsv4 gene. Our data demonstrate that gain of virulence mutation(s) by all avirulent viruses on Rsv4-genotype soybean is associated with a relative fitness loss in a susceptible host. The implications of this finding on the durable deployment of the Rsv4 gene in soybean are discussed.
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Affiliation(s)
- Y Wang
- Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, TN, 37996, USA
| | - M R Hajimorad
- Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, TN, 37996, USA
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17
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Anh VL, Anh NT, Tagle AG, Vy TTP, Inoue Y, Takumi S, Chuma I, Tosa Y. Rmg8, a New Gene for Resistance to Triticum Isolates of Pyricularia oryzae in Hexaploid Wheat. PHYTOPATHOLOGY 2015; 105:1568-72. [PMID: 26555672 DOI: 10.1094/phyto-02-15-0034-r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Blast, caused by Pyricularia oryzae, is one of the major diseases of wheat in South America. We identified a new gene for resistance to Triticum isolates of P. oryzae in common wheat 'S-615', and designated it "resistance to Magnaporthe grisea 8" (Rmg8). Rmg8 was assigned to chromosome 2B through molecular mapping with simple-sequence repeat markers. To identify an avirulence gene corresponding to Rmg8, Triticum isolate Br48 (avirulent on S-615) was crossed with 200R29 (virulent on S-615), an F1 progeny derived from a cross between an Eleusine isolate (MZ5-1-6) and Br48. Segregation analysis of their progeny revealed that avirulence of Br48 on S-615 was conditioned by a single gene, which was designated AVR-Rmg8. AVR-Rmg8 was closely linked to AVR-Rmg7, which corresponded to Rmg7 located on chromosome 2A of tetraploid wheat.
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Affiliation(s)
- Vu Lan Anh
- Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan
| | - Nguyen Tuan Anh
- Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan
| | | | - Trinh Thi Phuong Vy
- Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan
| | - Yoshihiro Inoue
- Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan
| | - Shigeo Takumi
- Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan
| | - Izumi Chuma
- Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan
| | - Yukio Tosa
- Graduate School of Agricultural Sciences, Kobe University, Kobe 657-8501, Japan
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18
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Wang Y, Khatabi B, Hajimorad MR. Amino acid substitution in P3 of Soybean mosaic virus to convert avirulence to virulence on Rsv4-genotype soybean is influenced by the genetic composition of P3. MOLECULAR PLANT PATHOLOGY 2015; 16:301-7. [PMID: 25040594 PMCID: PMC6638367 DOI: 10.1111/mpp.12175] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The modification of avirulence factors of plant viruses by one or more amino acid substitutions converts avirulence to virulence on hosts containing resistance genes. Limited experimental studies have been conducted on avirulence/virulence factors of plant viruses, in particular those of potyviruses, to determine whether avirulence/virulence sites are conserved among strains. In this study, the Soybean mosaic virus (SMV)-Rsv4 pathosystem was exploited to determine whether: (i) avirulence/virulence determinants of SMV reside exclusively on P3 regardless of virus strain; and (ii) the sites residing on P3 and crucial for avirulence/virulence of isolates belonging to strain G2 are also involved in virulence of avirulent isolates belonging to strain G7. The results confirm that avirulence/virulence determinants of SMV on Rsv4-genotype soybean reside exclusively on P3. Furthermore, the data show that sites involved in the virulence of SMV on Rsv4-genotype soybean vary among strains, with the genetic composition of P3 playing a crucial role.
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Affiliation(s)
- Y Wang
- Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, TN, 37996, USA
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19
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Janzac B, Tribodet M, Lacroix C, Moury B, Verrier JL, Jacquot E. Evolutionary Pathways to Break Down the Resistance of Allelic Versions of the PVY Resistance Gene va. PLANT DISEASE 2014; 98:1521-1529. [PMID: 30699784 DOI: 10.1094/pdis-11-13-1126-re] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Emergence of viral genotypes can make control strategies based on resistance genes ineffective. A few years after the deployment of tobacco genotypes carrying alleles of the Potato virus Y (PVY) recessive resistance gene va, virulent PVY isolates have been reported, suggesting the low durability of va. To have a broader view of the evolutionary processes involved in PVY adaptation to va, we studied mutational pathways leading to the emergence of PVY resistance-breaking populations. The viral genome-linked protein (VPg) has been described to be potentially involved in va adaptation. Analyses of the VPg sequence of PVY isolates sampled from susceptible and resistant tobacco allowed us to identify mutations in the central part of the VPg. Analysis of the virulence of wild-type isolates with known VPg sequences and of mutated versions of PVY infectious clones allowed us to (i) validate VPg as the PVY virulence factor corresponding to va, (ii) highlight the fact that virulence gain in PVY occurs rapidly and preferentially by substitution at position AA105 in the VPg, and (iii) show that the 101G substitution in the VPg of a PVYC isolate is responsible for cross-virulence toward two resistance sources. Moreover, it appears that the evolutionary pathway of PVY adaptation to va depends on both virus and host genetic backgrounds.
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Affiliation(s)
- B Janzac
- INRA-Agrocampus Ouest-Université Rennes 1, UMR 1349 IGEPP, F-35653 Le Rheu, France; Imperial Tobacco Group, SEITA, Institut du Tabac, Domaine de la Tour, F-24100 Bergerac France; and INRA-Cirad Montpellier SupAgro, UMR 385 BGPI, Cirad TA A-54K, Campus International de Baillarguet, F-34398 Montpellier, France
| | - M Tribodet
- INRA-Agrocampus Ouest-Université Rennes 1
| | - C Lacroix
- INRA-Agrocampus Ouest-Université Rennes 1 and Imperial Tobacco Group, SEITA, Institut du Tabac
| | - B Moury
- INRA, UR407 Pathologie Végétale, Domaine Saint Maurice, BP94, F-84140 Montfavet, France
| | - J L Verrier
- Imperial Tobacco Group, SEITA, Institut du Tabac
| | - E Jacquot
- INRA-Agrocampus Ouest-Université Rennes 1 and INRA-Cirad Montpellier SupAgro
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20
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Sorel M, Svanella-Dumas L, Candresse T, Acelin G, Pitarch A, Houvenaghel MC, German-Retana S. Key mutations in the cylindrical inclusion involved in lettuce mosaic virus adaptation to eIF4E-mediated resistance in lettuce. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1014-24. [PMID: 25105805 DOI: 10.1094/mpmi-04-14-0111-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We previously showed that allelic genes mol¹ and mo1² used to protect lettuce crops against Lettuce mosaic virus (LMV) correspond to mutant alleles of the gene encoding the eukaryotic translation initiation factor 4E. LMV resistance-breaking determinants map not only to the main potyvirus virulence determinant, a genome-linked viral protein, but also to the C-terminal region of the cylindrical inclusion (CI), with a key role of amino acid at position 621. Here, we show that the propagation of several non-lettuce isolates of LMV in mo1¹ plants is accompanied by a gain of virulence correlated with the presence in the CI C terminus of a serine at position 617 and the accumulation of mutations at positions 602 or 627. Whole-genome sequencing of native and evolved isolates showed that no other mutation could be associated with adaptation to mo1 resistance. Site-directed mutagenesis pinpointed the key role in the virulence of the combination of mutations at positions 602 and 617, in addition to position 621. The impact of these mutations on the fitness of the virus was evaluated, suggesting that the durability of mo1 resistance in the field relies on the fitness cost associated with the resistance-breaking mutations, the nature of the mutations, and their potential antagonistic effects.
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21
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Abstract
Viruses are common agents of plant infectious diseases. During last decades, worldwide agriculture production has been compromised by a series of epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that show new pathogenic and epidemiological properties. Virus emergence has been generally associated with ecological change or with intensive agronomical practices. However, the complete picture is much more complex since the viral populations constantly evolve and adapt to their new hosts and vectors. This chapter puts emergence of plant viruses into the framework of evolutionary ecology, genetics, and epidemiology. We will stress that viral emergence begins with the stochastic transmission of preexisting genetic variants from the reservoir to the new host, whose fate depends on their fitness on each hosts, followed by adaptation to new hosts or vectors, and finalizes with an efficient epidemiological spread.
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Affiliation(s)
- Santiago F Elena
- Instituto de Biología Molecular y Celular de Plantas, CSIC-UPV, Campus UPV, València, Spain; The Santa Fe Institute, Santa Fe, New Mexico, USA
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas, UPM-INIA, and ETSI Agrónomos, UPM, Campus de Montegancedo, Madrid, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas, UPM-INIA, and ETSI Agrónomos, UPM, Campus de Montegancedo, Madrid, Spain.
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22
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de Ronde D, Butterbach P, Kormelink R. Dominant resistance against plant viruses. FRONTIERS IN PLANT SCIENCE 2014; 5:307. [PMID: 25018765 PMCID: PMC4073217 DOI: 10.3389/fpls.2014.00307] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 06/10/2014] [Indexed: 05/17/2023]
Abstract
To establish a successful infection plant viruses have to overcome a defense system composed of several layers. This review will overview the various strategies plants employ to combat viral infections with main emphasis on the current status of single dominant resistance (R) genes identified against plant viruses and the corresponding avirulence (Avr) genes identified so far. The most common models to explain the mode of action of dominant R genes will be presented. Finally, in brief the hypersensitive response (HR) and extreme resistance (ER), and the functional and structural similarity of R genes to sensors of innate immunity in mammalian cell systems will be described.
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Affiliation(s)
- Dryas de Ronde
- Laboratory of Virology, Department of Plant Sciences, Wageningen University Wageningen, Netherlands
| | - Patrick Butterbach
- Laboratory of Virology, Department of Plant Sciences, Wageningen University Wageningen, Netherlands
| | - Richard Kormelink
- Laboratory of Virology, Department of Plant Sciences, Wageningen University Wageningen, Netherlands
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23
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Durable resistance: a key to sustainable management of pathogens and pests. INFECTION GENETICS AND EVOLUTION 2014; 27:446-55. [PMID: 24486735 DOI: 10.1016/j.meegid.2014.01.011] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 12/24/2013] [Accepted: 01/13/2014] [Indexed: 11/22/2022]
Abstract
This review briefly addresses what has been learned about resistance durability in recent years, as well as the questions that still remain. Molecular analyses of major gene interactions have potential to contribute to both breeding for resistance and improved understanding of virulence impacts on pathogen fitness. Though the molecular basis of quantitative resistance is less clear, substantial evidence has accumulated for the relative simplicity of inheritance. There is increasing evidence for specific interactions with quantitative resistance, though implications of this for durability are still unknown. Mechanisms by which resistance gene pyramids contribute to durability remain elusive, though ideas have been generated for identifying gene combinations that may be more durable. Though cultivar mixtures and related approaches have been used successfully, identifying the diseases and conditions that are most conducive to the use of diversity has been surprisingly difficult, and the selective influence of diversity on pathogen populations is complex. The importance of considering resistance durability in a landscape context has received increasing emphasis and is an important future area of research. Experimental systems are being developed to test resistance gene deployment strategies that previously could be addressed only with logic and observation. The value of molecular markers for identifying and pyramiding major genes is quite clear, but the successful use of quantitative trait loci (QTL) for marker-assisted selection of quantitative resistance will depend greatly on the degree to which the identified QTL are expressed in different genetic backgrounds. Transgenic approaches will likely provide opportunities for control of some recalcitrant pathogens, though issues of durability for transgenes are likely to be no different than other genes for resistance. The need for high quality phenotypic analysis and screening methodologies is a priority, and field-based studies are likely to remain of signal importance in the foreseeable future.
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24
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Khatabi B, Wen RH, Hajimorad MR. Fitness penalty in susceptible host is associated with virulence of Soybean mosaic virus on Rsv1-genotype soybean: a consequence of perturbation of HC-Pro and not P3. MOLECULAR PLANT PATHOLOGY 2013; 14:885-97. [PMID: 23782556 PMCID: PMC6638797 DOI: 10.1111/mpp.12054] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The multigenic Rsv1 locus in the soybean plant introduction (PI) 'PI96983' confers extreme resistance against the majority of Soybean mosaic virus (SMV) strains, including SMV-N, but not SMV-G7 and SMV-G7d. In contrast, in susceptible soybean cultivars lacking a functional Rsv1 locus, such as 'Williams82' (rsv1), SMV-N induces severe disease symptoms and accumulates to a high level, whereas both SMV-G7 and SMV-G7d induce mild symptoms and accumulate to a significantly lower level. Gain of virulence by SMV-N on Rsv1-genotype soybean requires concurrent mutations in both the helper-component proteinase (HC-Pro) and P3 cistrons. This is because of the presence of at least two resistance (R) genes, probably belonging to the nucleotide-binding leucine-rich repeat (NB-LRR) class, within the Rsv1 locus, independently mediating the recognition of HC-Pro or P3. In this study, we show that the majority of experimentally evolved mutational pathways that disrupt the avirulence functions of SMV-N on Rsv1-genotype soybean also result in mild symptoms and reduced accumulation, relative to parental SMV-N, in Williams82 (rsv1). Furthermore, the evaluation of SMV-N-derived HC-Pro and P3 chimeras, containing homologous sequences from virulent SMV-G7 or SMV-G7d strains, as well as SMV-N-derived variants containing HC-Pro or P3 point mutation(s) associated with gain of virulence, reveals a direct correlation between the perturbation of HC-Pro and a fitness penalty in Williams82 (rsv1). Collectively, these data demonstrate that gain of virulence by SMV on Rsv1-genotype soybean results in fitness loss in a previously susceptible soybean genotype, this being a consequence of mutations in HC-Pro, but not in P3.
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Affiliation(s)
- B Khatabi
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN, 37996, USA
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25
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Bornemann K, Varrelmann M. Effect of sugar beet genotype on the Beet necrotic yellow vein virus P25 pathogenicity factor and evidence for a fitness penalty in resistance-breaking strains. MOLECULAR PLANT PATHOLOGY 2013; 14:356-64. [PMID: 23282068 PMCID: PMC6638868 DOI: 10.1111/mpp.12012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Beet necrotic yellow vein virus (BNYVV), vectored by Polymyxa betae, causes rhizomania in sugar beet. For disease control, the cultivation of hybrids carrying Rz1 resistance is crucial, but is compromised by resistance-breaking (RB) strains with specific mutations in the P25 protein at amino acids 67-70 (tetrad). To obtain evidence for P25 variability from soil-borne populations, where the virus persists for decades, populations with wild-type (WT) and RB properties were analysed by P25 deep sequencing. The level of P25 variation in the populations analysed did not correlate with RB properties. Remarkably, one WT population contained P25 with RB mutations at a frequency of 11%. To demonstrate selection by Rz1 and the influence of RB mutations on relative fitness, competition experiments between strains were performed. Following a mixture of strains with four RNAs, a shift in tetrad variants was observed, suggesting that strains did not mix or transreplicate. The plant genotype exerted a clear influence on the frequency of RB tetrads. In Rz1 plants, the RB variants outcompeted the WT variants, and mostly vice versa in susceptible plants, demonstrating a relative fitness penalty of RB mutations. The strong genotype effect supports the hypothesized Rz1 RB strain selection with four RNAs, suggesting that a certain tetrad needs to become dominant in a population to influence its properties. Tetrad selection was not observed when an RB strain, with an additional P26 protein encoded by a fifth RNA, competed with a WT strain, supporting its role as a second BNYVV pathogenicity factor and suggesting the reassortment of both types.
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Affiliation(s)
- Kathrin Bornemann
- Department of Phytopathology, Institute of Sugar Beet Research, D-37079, Goettingen, Germany
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26
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Wen RH, Khatabi B, Ashfield T, Saghai Maroof MA, Hajimorad MR. The HC-Pro and P3 cistrons of an avirulent Soybean mosaic virus are recognized by different resistance genes at the complex Rsv1 locus. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:203-15. [PMID: 23051173 DOI: 10.1094/mpmi-06-12-0156-r] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The complex Rsv1 locus in soybean plant introduction (PI) 'PI96983' confers extreme resistance (ER) against Soybean mosaic virus (SMV) strain N but not SMV-G7 and SMV-G7d. Both the SMV helper-component proteinase (HC-Pro) and P3 cistrons can serve as avirulence factors recognized by Rsv1. To understand the genetics underlying recognition of the two cistrons, we have utilized two soybean lines (L800 and L943) derived from crosses between PI96983 (Rsv1) and Lee68 (rsv1) with distinct recombination events within the Rsv1 locus. L800 contains a single PI96983-derived member (3gG2) of an Rsv1-associated subfamily of nucleotide-binding leucine-rich repeat (NB-LRR) genes. In contrast, although L943 lacks 3gG2, it contains a suite of five other NB-LRR genes belonging to the same family. L800 confers ER against SMV-N whereas L943 allows limited replication at the inoculation site. SMV-N-derived chimeras containing HC-Pro from SMV-G7 or SMV-G7d gained virulence on L943 but not on L800 whereas those with P3 replacement gained virulence on L800 but not on L943. In reciprocal experiments, SMV-G7- and SMV-G7d-derived chimeras with HC-Pro replacement from SMV-N lost virulence on L943 but retained virulence on L800 whereas those with P3 replacement lost virulence on L800 while remaining virulent on L943. These data demonstrate that distinct resistance genes at the Rsv1 locus, likely belonging to the NB-LRR class, mediate recognition of HC-Pro and P3.
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Affiliation(s)
- R-H Wen
- Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, TN 37996, USA
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27
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Sekine KT, Tomita R, Takeuchi S, Atsumi G, Saitoh H, Mizumoto H, Kiba A, Yamaoka N, Nishiguchi M, Hikichi Y, Kobayashi K. Functional differentiation in the leucine-rich repeat domains of closely related plant virus-resistance proteins that recognize common avr proteins. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1219-29. [PMID: 22690804 DOI: 10.1094/mpmi-11-11-0289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The N' gene of Nicotiana sylvestris and L genes of Capsicum plants confer the resistance response accompanying the hypersensitive response (HR) elicited by tobamovirus coat proteins (CP) but with different viral specificities. Here, we report the identification of the N' gene. We amplified and cloned an N' candidate using polymerase chain reaction primers designed from L gene sequences. The N' candidate gene was a single 4143 base pairs fragment encoding a coiled-coil nucleotide-binding leucine-rich repeat (LRR)-type resistance protein of 1,380 amino acids. The candidate gene induced the HR in response to the coexpression of tobamovirus CP with the identical specificity as reported for N'. Analysis of N'-containing and tobamovirus-susceptible N. tabacum accessions supported the hypothesis that the candidate is the N' gene itself. Chimera analysis between N' and L(3) revealed that their LRR domains determine the spectrum of their tobamovirus CP recognition. Deletion and mutation analyses of N' and L(3) revealed that the conserved sequences in their C-terminal regions have important roles but contribute differentially to the recognition of common avirulence proteins. The results collectively suggest that Nicotiana N' and Capsicum L genes, which most likely evolved from a common ancestor, differentiated in their recognition specificity through changes in the structural requirements for LRR function.
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Fabre F, Rousseau E, Mailleret L, Moury B. Durable strategies to deploy plant resistance in agricultural landscapes. THE NEW PHYTOLOGIST 2012; 193:1064-1075. [PMID: 22260272 DOI: 10.1111/j.1469-8137.2011.04019.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The deployment of resistant crops often leads to the emergence of resistance-breaking pathogens that suppress the yield benefit provided by the resistance. Here, we theoretically explored how farmers' main leverages (resistant cultivar choice, resistance deployment strategy, landscape planning and cultural practices) can be best combined to achieve resistance durability while minimizing yield losses as a result of plant viruses. Assuming a gene-for-gene type of interaction, virus epidemics are modelled in a landscape composed of a mosaic of resistant and susceptible fields, subjected to seasonality, and a reservoir hosting viruses year-round. The model links the genetic and the epidemiological processes, shaping at nested scales the demogenetic dynamics of viruses. The choice of the resistance gene (characterized by the equilibrium frequency of the resistance-breaking virus at mutation-selection balance in a susceptible plant) is the most influential leverage of action. Our results showed that optimal strategies of resistance deployment range from 'mixture' (where susceptible and resistant cultivars coexist) to 'pure' strategies (with only resistant cultivar) depending on the resistance characteristics and the epidemiological context (epidemic incidence and landscape connectivity). We demonstrate and discuss gaps concerning virus epidemiology across the agro-ecological interface that must be filled to achieve sustainable disease management.
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Affiliation(s)
- Frédéric Fabre
- INRA, UR 407 Unité De Pathologie Végétale, F-84140 Montfavet, France
| | - Elsa Rousseau
- INRA, UR 407 Unité De Pathologie Végétale, F-84140 Montfavet, France
- INRA, UR 880 URIH, 400 route des Chappes, BP 167, F-06903 Sophia Antipolis, France
| | - Ludovic Mailleret
- INRA, UR 880 URIH, 400 route des Chappes, BP 167, F-06903 Sophia Antipolis, France
- INRIA, Biocore Team, F-06902 Sophia Antipolis, France
| | - Benoit Moury
- INRA, UR 407 Unité De Pathologie Végétale, F-84140 Montfavet, France
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Montarry J, Doumayrou J, Simon V, Moury B. Genetic background matters: a plant-virus gene-for-gene interaction is strongly influenced by genetic contexts. MOLECULAR PLANT PATHOLOGY 2011; 12:911-20. [PMID: 21726391 PMCID: PMC6640445 DOI: 10.1111/j.1364-3703.2011.00724.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Evolutionary processes responsible for parasite adaptation to their hosts determine our capacity to manage sustainably resistant plant crops. Most plant-parasite interactions studied so far correspond to gene-for-gene models in which the nature of the alleles present at a plant resistance locus and at a pathogen pathogenicity locus determine entirely the outcome of their confrontation. The interaction between the pepper pvr2 resistance locus and Potato virus Y (PVY) genome-linked protein VPg locus obeys this kind of model. Using synthetic chimeras between two parental PVY cDNA clones, we showed that the viral genetic background surrounding the VPg pathogenicity locus had a strong impact on the resistance breakdown capacity of the virus. Indeed, recombination of the cylindrical inclusion (CI) coding region between two PVY cDNA clones multiplied by six the virus capacity to break down the pvr2(3) -mediated resistance. High-throughput sequencing allowed the exploration of the diversity of PVY populations in response to the selection pressure of the pvr2(3) resistance. The CI chimera, which possessed an increased resistance breakdown capacity, did not show an increased mutation accumulation rate. Instead, selection of the most frequent resistance-breaking mutation seemed to be more efficient for the CI chimera than for the parental virus clone. These results echoed previous observations, which showed that the plant genetic background in which the pvr2(3) resistance gene was introduced modified strongly the efficiency of selection of resistance-breaking mutations by PVY. In a broader context, the PVY CI coding region is one of the first identified genetic factors to determine the evolvability of a plant virus.
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Chowda-Reddy RV, Sun H, Hill JH, Poysa V, Wang A. Simultaneous mutations in multi-viral proteins are required for soybean mosaic virus to gain virulence on soybean genotypes carrying different R genes. PLoS One 2011; 6:e28342. [PMID: 22140577 PMCID: PMC3227670 DOI: 10.1371/journal.pone.0028342] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 11/06/2011] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Genetic resistance is the most effective and sustainable approach to the control of plant pathogens that are a major constraint to agriculture worldwide. In soybean, three dominant R genes, i.e., Rsv1, Rsv3 and Rsv4, have been identified and deployed against Soybean mosaic virus (SMV) with strain-specificities. Molecular identification of virulent determinants of SMV on these resistance genes will provide essential information for the proper utilization of these resistance genes to protect soybean against SMV, and advance knowledge of virus-host interactions in general. METHODOLOGY/PRINCIPAL FINDINGS To study the gain and loss of SMV virulence on all the three resistance loci, SMV strains G7 and two G2 isolates L and LRB were used as parental viruses. SMV chimeras and mutants were created by partial genome swapping and point mutagenesis and then assessed for virulence on soybean cultivars PI96983 (Rsv1), L-29 (Rsv3), V94-5152 (Rsv4) and Williams 82 (rsv). It was found that P3 played an essential role in virulence determination on all three resistance loci and CI was required for virulence on Rsv1- and Rsv3-genotype soybeans. In addition, essential mutations in HC-Pro were also required for the gain of virulence on Rsv1-genotype soybean. To our best knowledge, this is the first report that CI and P3 are involved in virulence on Rsv1- and Rsv3-mediated resistance, respectively. CONCLUSIONS/SIGNIFICANCE Multiple viral proteins, i.e., HC-Pro, P3 and CI, are involved in virulence on the three resistance loci and simultaneous mutations at essential positions of different viral proteins are required for an avirulent SMV strain to gain virulence on all three resistance loci. The likelihood of such mutations occurring naturally and concurrently on multiple viral proteins is low. Thus, incorporation of all three resistance genes in a soybean cultivar through gene pyramiding may provide durable resistance to SMV.
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Affiliation(s)
- R. V. Chowda-Reddy
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
- Department of Biology, University of Western Ontario, London, Ontario, Canada
| | - Haiyue Sun
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - John H. Hill
- Department of Plant Pathology, Iowa State University, Ames, Iowa, United States of America
| | - Vaino Poysa
- Greenhouse and Processing Crops Research Centre, Agriculture and Agri-Food Canada, Harrow, Ontario, Canada
| | - Aiming Wang
- Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada
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Moury B, Caromel B, Johansen E, Simon V, Chauvin L, Jacquot E, Kerlan C, Lefebvre V. The helper component proteinase cistron of Potato virus Y induces hypersensitivity and resistance in Potato genotypes carrying dominant resistance genes on chromosome IV. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:787-797. [PMID: 21405985 DOI: 10.1094/mpmi-10-10-0246] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The Nc(tbr) and Ny(tbr) genes in Solanum tuberosum determine hypersensitive reactions, characterized by necrotic reactions and restriction of the virus systemic movement, toward isolates belonging to clade C and clade O of Potato virus Y (PVY), respectively. We describe a new resistance from S. sparsipilum which possesses the same phenotype and specificity as Nc(tbr) and is controlled by a dominant gene designated Nc(spl). Nc(spl) maps on potato chromosome IV close or allelic to Ny(tbr). The helper component proteinase (HC-Pro) cistron of PVY was shown to control necrotic reactions and resistance elicitation in plants carrying Nc(spl), Nc(tbr), and Ny(tbr). However, inductions of necrosis and of resistance to the systemic virus movement in plants carrying Nc(spl) reside in different regions of the HC-Pro cistron. Also, genomic determinants outside the HC-Pro cistron are involved in the systemic movement of PVY after induction of necroses on inoculated leaves of plants carrying Ny(tbr). These results suggest that the Ny(tbr) resistance may have been involved in the recent emergence of PVY isolates with a recombination breakpoint near the junction of HC-Pro and P3 cistrons in potato crops. Therefore, this emergence could constitute one of the rare examples of resistance breakdown by a virus which was caused by recombination instead of by successive accumulation of nucleotide substitutions.
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Affiliation(s)
- Benoît Moury
- INRA, UR407 Pathologie Vegetale, Montfavet, France.
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Desbiez C, Moury B, Lecoq H. The hallmarks of "green" viruses: do plant viruses evolve differently from the others? INFECTION GENETICS AND EVOLUTION 2011; 11:812-24. [PMID: 21382520 DOI: 10.1016/j.meegid.2011.02.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 02/22/2011] [Accepted: 02/24/2011] [Indexed: 12/13/2022]
Abstract
All viruses are obligatory parasites that must develop tight interactions with their hosts to complete their infectious cycle. Viruses infecting plants share many structural and functional similarities with those infecting other organisms, particularly animals and fungi. Quantitative data regarding their evolutionary mechanisms--generation of variability by mutation and recombination, changes in populations by selection and genetic drift have been obtained only recently, and appear rather similar to those measured for animal viruses.This review presents an update of our knowledge of the phylogenetic and evolutionary characteristics of plant viruses and their relation to their plant hosts, in comparison with viruses infecting other organisms.
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Affiliation(s)
- C Desbiez
- INRA, Unité de Pathologie Végétale UR407, F-84140 Montfavet, France.
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Hajimorad MR, Wen RH, Eggenberger AL, Hill JH, Maroof MAS. Experimental adaptation of an RNA virus mimics natural evolution. J Virol 2011; 85:2557-64. [PMID: 21191023 PMCID: PMC3067964 DOI: 10.1128/jvi.01935-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 12/21/2010] [Indexed: 11/20/2022] Open
Abstract
Identification of virulence determinants of viruses is of critical importance in virology. In search of such determinants, virologists traditionally utilize comparative genomics between a virulent and an avirulent virus strain and construct chimeras to map their locations. Subsequent comparison reveals sequence differences, and through analyses of site-directed mutants, key residues are identified. In the absence of a naturally occurring virulent strain, an avirulent strain can be functionally converted to a virulent variant via an experimental evolutionary approach. However, the concern remains whether experimentally evolved virulence determinants mimic those that have evolved naturally. To provide a direct comparison, we exploited a plant RNA virus, soybean mosaic virus (SMV), and its natural host, soybean. Through a serial in vivo passage experiment, the molecularly cloned genome of an avirulent SMV strain was converted to virulent variants on functionally immune soybean genotypes harboring resistance factor(s) from the complex Rsv1 locus. Several of the experimentally evolved virulence determinants were identical to those discovered through a comparative genomic approach with a naturally evolved virulent strain. Thus, our observations validate an experimental evolutionary approach to identify relevant virulence determinants of an RNA virus.
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Affiliation(s)
- M R Hajimorad
- Department of Entomology and Plant Pathology, The University of Tennessee, 205 Ellington Plant Sciences Bldg., Knoxville, TN 37996, USA.
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Tentchev D, Verdin E, Marchal C, Jacquet M, Aguilar JM, Moury B. Evolution and structure of Tomato spotted wilt virus populations: evidence of extensive reassortment and insights into emergence processes. J Gen Virol 2010; 92:961-73. [DOI: 10.1099/vir.0.029082-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Fraile A, Pagán I, Anastasio G, Sáez E, García-Arenal F. Rapid genetic diversification and high fitness penalties associated with pathogenicity evolution in a plant virus. Mol Biol Evol 2010; 28:1425-37. [PMID: 21131559 DOI: 10.1093/molbev/msq327] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Under the gene-for-gene model of host-pathogen coevolution, recognition of pathogen avirulence factors by host resistance factors triggers host defenses and limits infection. Theory predicts that the evolution of higher levels of pathogenicity will be associated with fitness penalties and that the cost of higher pathogenicity must be much smaller than that of not infecting the host. The analysis of pathogenicity costs is of academic and applied relevance, as these are determinants for the success of resistance genes bred into crops for disease control. However, most previous attempts of addressing this issue in plant pathogens yielded conflicting and inconclusive results. We have analyzed the costs of pathogenicity in pepper-infecting tobamoviruses defined by their ability to infect pepper plants with different alleles at the resistance locus L. We provide conclusive evidence of pathogenicity-associated costs by comparison of pathotype frequency with the fraction of the crop carrying the various resistance alleles, by timescaled phylogenies, and by temporal analyses of population dynamics and selection pressures using nucleotide sequences. In addition, experimental estimates of relative fitness under controlled conditions also provided evidence of high pathogenicity costs. These high pathogenicity costs may reflect intrinsic properties of plant virus genomes and should be considered in future models of host-parasite coevolution.
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Affiliation(s)
- Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA) and ETSI Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
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López C, Aramburu J, Galipienso L, Soler S, Nuez F, Rubio L. Evolutionary analysis of tomato Sw-5 resistance-breaking isolates of Tomato spotted wilt virus. J Gen Virol 2010; 92:210-5. [PMID: 20881087 DOI: 10.1099/vir.0.026708-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tomato spotted wilt virus (TSWV) causes severe economic losses in many crops worldwide and often overcomes resistant cultivars used for disease control. Comparison of nucleotide and amino acid sequences suggested that tomato resistance conferred by the gene Sw-5 can be overcome by the amino acid substitution C to Y at position 118 (C118Y) or T120N in the TSWV movement protein, NSm. Phylogenetic analysis revealed that substitution C118Y has occurred independently three times in the studied isolates by convergent evolution, whereas the substitution T120N was a unique event. Analysis of rates of non-synonymous and synonymous changes at individual codons showed that substitution C118Y was positively selected.
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Affiliation(s)
- Carmelo López
- COMAV-Universidad Politécnica de Valencia, 46022 Valencia, Spain
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Janzac B, Montarry J, Palloix A, Navaud O, Moury B. A point mutation in the polymerase of Potato virus Y confers virulence toward the Pvr4 resistance of pepper and a high competitiveness cost in susceptible cultivar. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:823-830. [PMID: 20459321 DOI: 10.1094/mpmi-23-6-0823] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
To understand why the Pvr4 resistance of pepper against Potyvirus spp. remained durable in field conditions while virulent Potato virus Y (PVY) variants could be selected in the laboratory, we studied the molecular mechanisms which generated these variants and the consequences on viral fitness. Using a reverse genetics approach with an infectious cDNA clone of PVY, we found that the region coding for the NIb protein (RNA-dependent RNA polymerase) of PVY was the avirulence factor corresponding to Pvr4 and that a single nonsynonymous nucleotide substitution in that region, an adenosine to guanosine substitution at position 8,424 of the PVY genome (A(8424)G), was sufficient for virulence. This substitution imposed a high competitiveness cost to the virus against an avirulent PVY variant in plants devoid of Pvr4. In addition, during serial passages in susceptible pepper plants, the only observed possibility of the virulent mutant to increase its fitness was through the G(8424)A reversion, strengthening the high durability potential of the Pvr4 resistance. This is in accordance with the fact that the NIb protein is one of the most constrained proteins expressed by the PVY genome and, more generally, by Potyvirus spp., and with a previously developed model predicting the durability of virus resistances as a function of the evolutionary constraint applied on corresponding avirulence factors.
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Fraile A, García-Arenal F. The coevolution of plants and viruses: resistance and pathogenicity. Adv Virus Res 2010; 76:1-32. [PMID: 20965070 DOI: 10.1016/s0065-3527(10)76001-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Virus infection may damage the plant, and plant defenses are effective against viruses; thus, it is currently assumed that plants and viruses coevolve. However, and despite huge advances in understanding the mechanisms of pathogenicity and virulence in viruses and the mechanisms of virus resistance in plants, evidence in support of this hypothesis is surprisingly scant, and refers almost only to the virus partner. Most evidence for coevolution derives from the study of highly virulent viruses in agricultural systems, in which humans manipulate host genetic structure, what determines genetic changes in the virus population. Studies have focused on virus responses to qualitative resistance, either dominant or recessive but, even within this restricted scenario, population genetic analyses of pathogenicity and resistance factors are still scarce. Analyses of quantitative resistance or tolerance, which could be relevant for plant-virus coevolution, lag far behind. A major limitation is the lack of information on systems in which the host might evolve in response to virus infection, that is, wild hosts in natural ecosystems. It is presently unknown if, or under which circumstances, viruses do exert a selection pressure on wild plants, if qualitative resistance is a major defense strategy to viruses in nature, or even if characterized genes determining qualitative resistance to viruses did indeed evolve in response to virus infection. Here, we review evidence supporting plant-virus coevolution and point to areas in need of attention to understand the role of viruses in plant ecosystem dynamics, and the factors that determine virus emergence in crops.
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Affiliation(s)
- Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA) and E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, Madrid, Spain
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