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Demirjian C, Vailleau F, Berthomé R, Roux F. Genome-wide association studies in plant pathosystems: success or failure? TRENDS IN PLANT SCIENCE 2023; 28:471-485. [PMID: 36522258 DOI: 10.1016/j.tplants.2022.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 10/28/2022] [Accepted: 11/16/2022] [Indexed: 06/17/2023]
Abstract
Harnessing natural genetic variation is an established alternative to artificial genetic variation for investigating the molecular dialog between partners in plant pathosystems. Herein, we review the successes of genome-wide association studies (GWAS) in both plants and pathogens. While GWAS in plants confirmed that the genetic architecture of disease resistance is polygenic, dynamic during the infection kinetics, and dependent on the environment, GWAS shortened the time of identification of quantitative trait loci (QTLs) and revealed both complex epistatic networks and a genetic architecture dependent upon the geographical scale. A similar picture emerges from the few GWAS in pathogens. In addition, the ever-increasing number of functionally validated QTLs has revealed new molecular plant defense mechanisms and pathogenicity determinants. Finally, we propose recommendations to better decode the disease triangle.
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Affiliation(s)
- Choghag Demirjian
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France
| | - Fabienne Vailleau
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France
| | - Richard Berthomé
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France
| | - Fabrice Roux
- LIPME, INRAE, CNRS, Université de Toulouse, Castanet-Tolosan, France.
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Pabuayon ICM, Kitazumi A, Cushman KR, Singh RK, Gregorio GB, Dhatt B, Zabet-Moghaddam M, Walia H, de los Reyes BG. Novel and Transgressive Salinity Tolerance in Recombinant Inbred Lines of Rice Created by Physiological Coupling-Uncoupling and Network Rewiring Effects. FRONTIERS IN PLANT SCIENCE 2021; 12:615277. [PMID: 33708229 PMCID: PMC7940525 DOI: 10.3389/fpls.2021.615277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 02/03/2021] [Indexed: 06/01/2023]
Abstract
The phenomenon of transgressive segregation, where a small minority of recombinants are outliers relative to the range of parental phenotypes, is commonly observed in plant breeding populations. While this phenomenon has been attributed to complementation and epistatic effects, the physiological and developmental synergism involved have not been fully illuminated by the QTL mapping approach alone, especially for stress-adaptive traits involving highly complex interactions. By systems-level profiling of the IR29 × Pokkali recombinant inbred population of rice, we addressed the hypothesis that novel salinity tolerance phenotypes are created by reconfigured physiological networks due to positive or negative coupling-uncoupling of developmental and physiological attributes of each parent. Real-time growth and hyperspectral profiling distinguished the transgressive individuals in terms of stress penalty to growth. Non-parental network signatures that led to either optimal or non-optimal integration of developmental with stress-related mechanisms were evident at the macro-physiological, biochemical, metabolic, and transcriptomic levels. Large positive net gain in super-tolerant progeny was due to ideal complementation of beneficial traits while shedding antagonistic traits. Super-sensitivity was explained by the stacking of multiple antagonistic traits and loss of major beneficial traits. The synergism uncovered by the phenomics approach in this study supports the modern views of the Omnigenic Theory, emphasizing the synergy or lack thereof between core and peripheral components. This study also supports a breeding paradigm rooted on genomic modeling from multi-dimensional genetic, physiological, and phenotypic profiles to create novel adaptive traits for new crop varieties of the 21st century.
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Affiliation(s)
- Isaiah C. M. Pabuayon
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, United States
| | - Ai Kitazumi
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, United States
| | - Kevin R. Cushman
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, United States
| | | | | | - Balpreet Dhatt
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Masoud Zabet-Moghaddam
- Center for Biotechnology and Genomics, Texas Tech University, Lubbock, TX, United States
| | - Harkamal Walia
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, United States
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Sharma S, Sahu R, Navathe S, Mishra VK, Chand R, Singh PK, Joshi AK, Pandey SP. Natural Variation in Elicitation of Defense-Signaling Associates to Field Resistance Against the Spot Blotch Disease in Bread Wheat ( Triticum aestivum L.). FRONTIERS IN PLANT SCIENCE 2018; 9:636. [PMID: 29868089 PMCID: PMC5964214 DOI: 10.3389/fpls.2018.00636] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 04/24/2018] [Indexed: 05/03/2023]
Abstract
Spot blotch, caused by the hemibiotropic fungus Bipolaris sorokiniana, is amongst the most damaging diseases of wheat. Still, natural variation in expression of biochemical traits that determine field resistance to spot blotch in wheat remain unaddressed. To understand how genotypic variations relate to metabolite profiles of the components of defense-signaling and the plant performance, as well as to discover novel sources of resistance against spot blotch, we have conducted field studies using 968 wheat genotypes at 5 geographical locations in South-Asia in 2 years. 46 genotypes were identified as resistant. Further, in independent confirmatory trials in subsequent 3 years, over 5 geographical locations, we re-characterized 55 genotypes for their resistance (above 46 along with Yangmai#6, a well characterized resistant genotype, and eight susceptible genotypes). We next determined time-dependent spot blotch-induced metabolite profiles of components of defense-signaling as well as levels of enzymatic components of defense pathway (such as salicylic acid (SA), phenolic acids, and redox components), and derived co-variation patterns with respect to resistance in these 55 genotypes. Spot blotch-induced SA accumulation was negatively correlated to disease progression. Amongst phenolic acids, syringic acid was most strongly inversely correlated to disease progression, indicating a defensive function, which was independently confirmed. Thus, exploring natural variation proved extremely useful in determining traits influencing phenotypic plasticity and adaptation to complex environments. Further, by overcoming environmental heterogeneity, our study identifies germplasm and biochemical traits that are deployable for spot blotch resistance in wheat along South-Asia.
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Affiliation(s)
- Sandeep Sharma
- CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, India
| | - Ranabir Sahu
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, India
| | - Sudhir Navathe
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India
| | - Vinod K. Mishra
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India
| | - Ramesh Chand
- Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India
| | - Pawan K. Singh
- The International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico
| | - Arun K. Joshi
- The International Maize and Wheat Improvement Center (CIMMYT), New Delhi, India
| | - Shree P. Pandey
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Kolkata, India
- *Correspondence: Shree P. Pandey
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Nuismer SL, Jenkins CE, Dybdahl MF. Identifying coevolving loci using interspecific genetic correlations. Ecol Evol 2017; 7:6894-6903. [PMID: 28904769 PMCID: PMC5587482 DOI: 10.1002/ece3.3107] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 05/05/2017] [Accepted: 05/08/2017] [Indexed: 01/16/2023] Open
Abstract
Evaluating the importance of coevolution for a wide range of evolutionary questions, such as the role parasites play in the evolution of sexual reproduction, requires that we understand the genetic basis of coevolutionary interactions. Despite its importance, little progress has been made identifying the genetic basis of coevolution, largely because we lack tools designed specifically for this purpose. Instead, coevolutionary studies are often forced to re-purpose single species techniques. Here, we propose a novel approach for identifying the genes mediating locally adapted coevolutionary interactions that relies on spatial correlations between genetic marker frequencies in the interacting species. Using individual-based multi-locus simulations, we quantify the performance of our approach across a range of coevolutionary genetic models. Our results show that when one species is strongly locally adapted to the other and a sufficient number of populations can be sampled, our approach accurately identifies functionally coupled host and parasite genes. Although not a panacea, the approach we outline here could help to focus the search for coevolving genes in a wide variety of well-studied systems for which substantial local adaptation has been demonstrated.
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Affiliation(s)
| | | | - Mark F. Dybdahl
- School of Biological SciencesWashington State UniversityPullmanWAUSA
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Allu AD, Brotman Y, Xue GP, Balazadeh S. Transcription factor ANAC032 modulates JA/SA signalling in response to Pseudomonas syringae infection. EMBO Rep 2016; 17:1578-1589. [PMID: 27632992 DOI: 10.15252/embr.201642197] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 08/23/2016] [Indexed: 11/09/2022] Open
Abstract
Responses to pathogens, including host transcriptional reprogramming, require partially antagonistic signalling pathways dependent on the phytohormones salicylic (SA) and jasmonic (JA) acids. However, upstream factors modulating the interplay of these pathways are not well characterized. Here, we identify the transcription factor ANAC032 from Arabidopsis thaliana as one such regulator in response to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pst). ANAC032 directly represses MYC2 activation upon Pst attack, resulting in blockage of coronatine-mediated stomatal reopening which restricts entry of bacteria into plant tissue. Furthermore, ANAC032 activates SA signalling by repressing NIMIN1, a key negative regulator of SA-dependent defence. Finally, ANAC032 reduces expression of JA-responsive genes, including PDF1.2A Thus, ANAC032 enhances resistance to Pst by generating an orchestrated transcriptional output towards key SA- and JA-signalling genes coordinated through direct binding of ANAC032 to the MYC2, NIMIN1 and PDF1.2A promoters.
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Affiliation(s)
- Annapurna Devi Allu
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany.,Max-Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Yariv Brotman
- Max-Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Gang-Ping Xue
- CSIRO Agriculture Flagship, St. Lucia, QLD, Australia
| | - Salma Balazadeh
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany .,Max-Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
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Shahnejat-Bushehri S, Nobmann B, Devi Allu A, Balazadeh S. JUB1 suppresses Pseudomonas syringae-induced defense responses through accumulation of DELLA proteins. PLANT SIGNALING & BEHAVIOR 2016; 11:e1181245. [PMID: 27159137 PMCID: PMC4973753 DOI: 10.1080/15592324.2016.1181245] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Phytohormones act in concert to coordinate plant growth and the response to environmental cues. Gibberellins (GAs) are growth-promoting hormones that recently emerged as modulators of plant immune signaling. By regulating the stability of DELLA proteins, GAs intersect with the signaling pathways of the classical primary defense hormones, salicylic acid (SA) and jasmonic acid (JA), thereby altering the final outcome of the immune response. DELLA proteins confer resistance to necrotrophic pathogens by potentiating JA signaling and raise the susceptibility to biotrophic pathogens by attenuating the SA pathway. Here, we show that JUB1, a core element of the GA - brassinosteroid (BR) - DELLA regulatory module, functions as a negative regulator of defense responses against Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and mediates the crosstalk between growth and immunity.
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Affiliation(s)
- Sara Shahnejat-Bushehri
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
- Max-Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Barbara Nobmann
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
- Max-Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Annapurna Devi Allu
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
- Max-Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
- CONTACT Salma Balazadeh ; Annapurna Devi Allu
| | - Salma Balazadeh
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
- Max-Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
- CONTACT Salma Balazadeh ; Annapurna Devi Allu
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Ahmad S, Van Hulten M, Martin J, Pieterse CMJ, Van Wees SCM, Ton J. Genetic dissection of basal defence responsiveness in accessions of Arabidopsis thaliana. PLANT, CELL & ENVIRONMENT 2011; 34:1191-206. [PMID: 21414016 DOI: 10.1111/j.1365-3040.2011.02317.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Basal resistance involves a multitude of pathogen- and herbivore-inducible defence mechanisms, ranging from localized callose deposition to systemic defence gene induction by salicylic acid (SA) and jasmonic acid (JA). In this study, we have explored and dissected genetic variation in the responsiveness of basal defence mechanisms within a selection of Arabidopsis accessions. Responsiveness of JA-induced PDF1.2 gene expression was associated with enhanced basal resistance against the necrotrophic fungus Plectosphaerella cucumerina and the herbivore Spodoptera littoralis. Conversely, accessions showing augmented PR-1 induction upon SA treatment were more resistant to the hemi-biotrophic pathogen Pseudomonas syringae, and constitutively expressed defence-related transcription factor (TF) genes. Unexpectedly, accessions with primed responsiveness to SA deposited comparatively little callose after treatment with microbe-associated molecular patterns. A quantitative trait locus (QTL) analysis identified two loci regulating flagellin-induced callose and one locus regulating SA-induced PR-1 expression. The latter QTL was found to contribute to basal resistance against P. syringae. None of the defence regulatory QTLs influenced plant growth, suggesting that the constitutive defence priming conferred by these loci is not associated with major costs on plant growth. Our study demonstrates that natural variation in basal resistance can be exploited to identify genetic loci that prime the plant's basal defence arsenal.
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Affiliation(s)
- Shakoor Ahmad
- Rothamsted Research, Centre of Sustainable Pest and Disease Management, West Common, Harpenden, Herts, UK
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Ahmad S, Gordon-Weeks R, Pickett J, Ton J. Natural variation in priming of basal resistance: from evolutionary origin to agricultural exploitation. MOLECULAR PLANT PATHOLOGY 2010; 11:817-27. [PMID: 21029325 PMCID: PMC6640509 DOI: 10.1111/j.1364-3703.2010.00645.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Biotic stress has a major impact on the process of natural selection in plants. As plants have evolved under variable environmental conditions, they have acquired a diverse spectrum of defensive strategies against pathogens and herbivores. Genetic variation in the expression of plant defence offers valuable insights into the evolution of these strategies. The 'zigzag' model, which describes an ongoing arms race between inducible plant defences and their suppression by pathogens, is now a commonly accepted model of plant defence evolution. This review explores additional strategies by which plants have evolved to cope with biotic stress under different selective circumstances. Apart from interactions with plant-beneficial micro-organisms that can antagonize pathogens directly, plants have the ability to prime their immune system in response to selected environmental signals. This defence priming offers disease protection that is effective against a broad spectrum of virulent pathogens, as long as the augmented defence reaction is expressed before the invading pathogen has the opportunity to suppress host defences. Furthermore, priming has been shown to be a cost-efficient defence strategy under relatively hostile environmental conditions. Accordingly, it is possible that selected plant varieties have evolved a constitutively primed immune system to adapt to levels of disease pressure. Here, we examine this hypothesis further by evaluating the evidence for natural variation in the responsiveness of basal defence mechanisms, and discuss how this genetic variation can be exploited in breeding programmes to provide sustainable crop protection against pests and diseases.
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Affiliation(s)
- Shakoor Ahmad
- Department of Biological Chemistry, Rothamsted Research, West Common Harpenden, Hertfordshire AL5 2JQ, UK
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Gao L, Roux F, Bergelson J. Quantitative fitness effects of infection in a gene-for-gene system. THE NEW PHYTOLOGIST 2009; 184:485-494. [PMID: 19659661 PMCID: PMC4311775 DOI: 10.1111/j.1469-8137.2009.02959.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
* It is often assumed that pathogen infection decreases plant fitness, thereby driving the evolution of plant resistance (R) genes. However, the impact of bacterial pathogens on fitness has been shown to be relatively subtle, ranging from positive to negative. * In this study, we focus on the Rps5-mediated resistance in Arabidopsis thaliana and examine the fitness effects of resistance by experimentally infecting resistant (R) and susceptible (S) plants with a natural avirulent Pseudomonas syringae strain at each of three initial infection dosage levels. Our methodology ensured control of the plant genetic backgrounds; within each of two natural accessions we created isolines varying in the presence or absence of Rps5. * In terms of lifetime fitness, R plants outperformed their S controls by 9.6-32% when infected by a pathogen carrying an associated Avr gene, depending on the initial dosage levels and genetic backgrounds. * We also found that the naturally R line, Col-0, is more tolerant than the naturally S accession, Ga-0. The negative impact of infection on fitness was 20% less in Col-0 than Ga-0. We found no effect of Rps5 itself on the tolerance of either accession. We therefore failed to find evidence for a trade-off between tolerance and resistance.
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Affiliation(s)
- Liping Gao
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
| | - Fabrice Roux
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
| | - Joy Bergelson
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA
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Jubault M, Lariagon C, Simon M, Delourme R, Manzanares-Dauleux MJ. Identification of quantitative trait loci controlling partial clubroot resistance in new mapping populations of Arabidopsis thaliana. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2008; 117:191-202. [PMID: 18427770 DOI: 10.1007/s00122-008-0765-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 04/03/2008] [Indexed: 05/02/2023]
Abstract
To date, mechanisms of partial quantitative resistance, under polygenic control, remain poorly understood, studies of the molecular basis of disease resistance have mainly focused on qualitative variation under oligogenic control. However, oligogenic conferred resistance is rapidly overcome by the pathogen and knowledge of the relationship between qualitative and quantitative resistance is necessary to develop durably resistant cultivars. In this study, we exploited the Arabidopsis thaliana-Plasmodiophora brassicae pathosystem to decipher the genetic architecture determining partial resistance. This soil-borne pathogen causes clubroot, one of the economically most important diseases of Brassica crops in the world. A quantitative trait locus (QTL) approach was carried out using two segregating populations (F(2) and recombinant inbred lines) from crosses between the partially resistant accession Burren and the susceptible accession Columbia. Four additive QTLs (one moderate and three minor) controlling partial resistance to clubroot were identified, all the resistance alleles being derived from the partially resistant parent. In addition, four epistatic regions, which have no additive effect on resistance, were also found to be involved in partial resistance. An examination of candidate genes suggested that a potentially diverse array of mechanisms is related to the different QTLs. By fine-mapping and cloning these regions, the mechanisms involved in partial resistance will be identified.
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Affiliation(s)
- Mélanie Jubault
- Amélioration des Plantes et Biotechnologies Végétales, UMR118 INRA-Agrocampus Rennes-Université de Rennes 1, BP35327, 35653, Le Rheu Cedex, France
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11
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Holub EB. Natural variation in innate immunity of a pioneer species. CURRENT OPINION IN PLANT BIOLOGY 2007; 10:415-24. [PMID: 17631039 DOI: 10.1016/j.pbi.2007.05.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 05/21/2007] [Accepted: 05/23/2007] [Indexed: 05/05/2023]
Abstract
By 2010, we will have detailed knowledge about the genome of Arabidopsis thaliana from a Linnean-like effort by an international research community to identify nearly all of the genes in the species and to classify the products that these genes encode according to a primary function in a generic plant cell. To know the wild species, however, we will require knowledge of which genes provide the raw material for phenotypic variation and natural selection, and consequently affect the adaptability of individual plants and local populations across their geographic range, and ultimately survival of the species. Natural variation in innate immunity will be at the forefront of this exciting research frontier as a model for the molecular ecology of plant-microbe interactions.
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Affiliation(s)
- Eric B Holub
- Warwick-HRI, University of Warwick, Wellesbourne, UK.
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12
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Kover PX, Cheverud J. The genetic basis of quantitative variation in susceptibility of Arabidopsis thaliana to Pseudomonas syringae (Pst DC3000): evidence for a new genetic factor of large effect. THE NEW PHYTOLOGIST 2007; 174:172-181. [PMID: 17335507 DOI: 10.1111/j.1469-8137.2007.01985.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
* Pathogens represent an important threat to plant communities and agriculture, and can shape many aspects of plant evolution. Natural variation in plant disease susceptibility is typically quantitative, yet studies on the molecular basis of disease resistance have focused mainly on qualitative variation. * Here we investigated the genetic architecture of quantitative susceptibility to the bacterium Pseudomonas syringae by performing a quantitative trait locus (QTL) analysis on the F2 progeny of two natural accessions of Arabidopsis thaliana under two nutrient treatments. * We found that a single QTL explains most of the variation (77%) in susceptibility between accessions Columbia (Col-0) and San Feliu-2 (Sf-2), and its effect is independent of nutrients. The Sf-2 allele at this QTL is dominant and can reduce the bacterial population size by 31-fold, much like a classical resistance (R) gene. However, minor QTLs, whose effects are altered by nutrient treatment, were also detected. * Surprisingly, we found that none of the QTLs for susceptibility had any effect on fruit production, suggesting that the use of resistance genes for crop improvement and evolutionary analysis of plant-pathogen interactions requires caution.
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Affiliation(s)
- Paula X Kover
- University of Manchester, Faculty of Life Sciences, Michael Smith Building, Room C.1261, Manchester M13 9PT, UK
| | - James Cheverud
- Washington University Medical School, Department of Anatomy and Neurobiology, 660 S. Euclid Ave., St Louis, MO 631110, USA
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13
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Perchepied L, Kroj T, Tronchet M, Loudet O, Roby D. Natural variation in partial resistance to Pseudomonas syringae is controlled by two major QTLs in Arabidopsis thaliana. PLoS One 2006; 1:e123. [PMID: 17205127 PMCID: PMC1762404 DOI: 10.1371/journal.pone.0000123] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 11/30/2006] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Low-level, partial resistance is pre-eminent in natural populations, however, the mechanisms underlying this form of resistance are still poorly understood. METHODOLOGY/PRINCIPAL FINDINGS In the present study, we used the model pathosystem Pseudomonas syringae pv. tomato DC3000 (Pst) - Arabidopsis thaliana to study the genetic basis of this form of resistance. Phenotypic analysis of a set of Arabidopsis accessions, based on evaluation of in planta pathogen growth revealed extensive quantitative variation for partial resistance to Pst. It allowed choosing a recombinant inbred line (RIL) population derived from a cross between the accessions Bayreuth and Shahdara for quantitative genetic analysis. Experiments performed under two different environmental conditions led to the detection of two major and two minor quantitative trait loci (QTLs) governing partial resistance to Pst and called PRP-Ps1 to PRP-Ps4. The two major QTLs, PRP-Ps1 and PRP-Ps2, were confirmed in near isogenic lines (NILs), following the heterogeneous inbred families (HIFs) strategy. Analysis of marker gene expression using these HIFs indicated a negative correlation between the induced amount of transcripts of SA-dependent genes PR1, ICS and PR5, and the in planta bacterial growth in the HIF segregating at PRP-Ps2 locus, suggesting an implication of PRP-Ps2 in the activation of SA dependent responses. CONCLUSIONS/SIGNIFICANCE These results show that variation in partial resistance to Pst in Arabidopsis is governed by relatively few loci, and the validation of two major loci opens the way for their fine mapping and their cloning, which will improve our understanding of the molecular mechanisms underlying partial resistance.
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Affiliation(s)
- Laure Perchepied
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
| | - Thomas Kroj
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
| | - Maurice Tronchet
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
| | - Olivier Loudet
- National Institute for Agronomical Research (INRA), Versailles, France
| | - Dominique Roby
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
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14
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Goss EM, Bergelson J. Fitness consequences of infection of Arabidopsis thaliana with its natural bacterial pathogen Pseudomonas viridiflava. Oecologia 2006; 152:71-81. [PMID: 17180370 DOI: 10.1007/s00442-006-0631-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Accepted: 11/21/2006] [Indexed: 11/27/2022]
Abstract
Variation in plant resistance to pathogen infection is commonly observed in interactions between wild plants and their foliar pathogens. Models of host-pathogen interactions indicate that a large cost of infection is generally necessary to maintain this variation, yet there is limited evidence that foliar pathogens cause detectable fitness reductions in wild host plants. Most published work has focused on fungal pathogens. Pseudomonas viridiflava, a common bacterial pathogen of the annual weed Arabidopsis thaliana across its range, comprises two distinct genetic clades that cause disease symptoms of different severity. Here we measured the extent of infection of wild A. thaliana populations in the Midwest, USA, and examined the effect on seed production, in field and growth-chamber experiments, of experimental inoculation with isolates from the two clades. We found infection with P. viridiflava varied from 0 to 56% in Midwest A. thaliana populations, with the possibility of several leaves per plant infected later in the growing season. In the growth chambers, experimental inoculation reduced seed set by averages of 15 and 11% for clades A and B, respectively. In the field experiment, only clade A affected plant fitness significantly, reducing seed set by an average of 38%. Underlying these average effects we observed both negative and positive effects of infection, and variation in both fitness among plant genotypes and sensitivity to environmental conditions.
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Affiliation(s)
- Erica M Goss
- Department of Ecology and Evolution, University of Chicago, 1101 E. 57th Street, Chicago, IL 60637, USA.
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