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Mahalingam T, Chen W, Rajapakse CS, Somachandra KP, Attanayake RN. Genetic Diversity and Recombination in the Plant Pathogen Sclerotinia sclerotiorum Detected in Sri Lanka. Pathogens 2020; 9:E306. [PMID: 32331222 PMCID: PMC7238271 DOI: 10.3390/pathogens9040306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/14/2020] [Accepted: 04/17/2020] [Indexed: 01/20/2023] Open
Abstract
Sclerotinia sclerotiorum is an important fungal pathogen on many economically important crops including cabbage worldwide. Even though population structure and genetic diversity of S. sclerotiorum is well studied in temperate climatic conditions, only a few studies have been conducted in tropical countries. It is also not clear whether the populations are clonal or recombining in the tropics. In filling this information gap, 47 isolates of S. sclerotiorum were collected from commercial cabbage (Brassica oleracea L.) fields in Nuwara Eliya district of Sri Lanka, where the disease has been previously reported. All the isolates were subjected to genetic diversity study using mycelial compatibility grouping and microsatellite markers. Fourteen mycelial compatibility groups (MCGs) and 23 multilocus haplotypes (MLHs) were recorded. Mean expected heterozygosity of the population was 0.56. MLHs were weakly correlated with MCGs. Population genetic structure analysis and principal coordinates identified three genetic clusters. Genetic recombination was inferred within each genetic cluster when isolates were subjected to clone correction. There was evidence of multiple infections on single plant as detected by the presence of more than one MCG on each cabbage plant. However, multiple infections did not increase the disease severity in detached leaf assay. We found high genetic diversity and recombination of S. sclerotiorum population in a tropical country, Sri Lanka. Importance of detecting genetic structure when inferring recombination was also highlighted.
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Affiliation(s)
- Thirega Mahalingam
- Department of Plant and Molecular Biology, University of Kelaniya, Kelaniya 11600, Sri Lanka;
| | - Weidong Chen
- United States Department of Agriculture-Agriculture Research Service (USDA-ARS), Grain Legume Genetics and Physiology Research Unit, Washington State University, Pullman, WA 99164, USA;
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Laine AL. Context-dependent effects of induced resistance under co-infection in a plant-pathogen interaction. Evol Appl 2011; 4:696-707. [PMID: 25568016 PMCID: PMC3352536 DOI: 10.1111/j.1752-4571.2011.00194.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 05/12/2011] [Indexed: 12/31/2022] Open
Abstract
The ability of a parasite strain to establish and grow on its host may be drastically altered by simultaneous infection by other parasite strains, and dynamics under multiple infection have been suggested to be a major force driving pathogen evolution. Here, I studied whether hosts' induced defenses mediate dynamics of multiple infection of the fungal pathogen, Podosphaera plantaginis, infecting Plantago lanceolata. A laboratory study of sequential infections, where interaction between pathogen strains was prevented, showed that ability to establish remained unaffected, but prior infection elevates the host's resistance to the degree that subsequent infection development is significantly reduced. However, when inoculated plants and their healthy controls were planted back into their natural populations, hosts with prior infection became more heavily infected by the subsequent infections than the initially healthy plants. Hence, a controlled short-term laboratory study is a poor predictor of the host's ability to mediate multiple infection during the course of natural epidemics. These results have applied implications for priming where the plants' defenses are elicited to provide protection against further attack, highlighting the importance of testing priming under natural conditions for relevant time scales.
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Affiliation(s)
- Anna-Liisa Laine
- Metapopulation Research Group, Department of Biosciences, University of Helsinki Finland ; Department of Biology, University of Turku Turku, Finland
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López-Villavicencio M, Jonot O, Coantic A, Hood ME, Enjalbert J, Giraud T. Multiple infections by the anther smut pathogen are frequent and involve related strains. PLoS Pathog 2007; 3:e176. [PMID: 18020704 PMCID: PMC2077905 DOI: 10.1371/journal.ppat.0030176] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Accepted: 10/03/2007] [Indexed: 11/18/2022] Open
Abstract
Population models of host-parasite interactions predict that when different parasite genotypes compete within a host for limited resources, those that exploit the host faster will be selected, leading to an increase in parasite virulence. When parasites sharing a host are related, however, kin selection should lead to more cooperative host exploitation that may involve slower rates of parasite reproduction. Despite their potential importance, studies that assess the prevalence of multiple genotype infections in natural populations remain rare, and studies quantifying the relatedness of parasites occurring together as natural multiple infections are particularly scarce. We investigated multiple infections in natural populations of the systemic fungal plant parasite Microbotryum violaceum, the anther smut of Caryophyllaceae, on its host, Silene latifolia. We found that multiple infections can be extremely frequent, with different fungal genotypes found in different stems of single plants. Multiple infections involved parasite genotypes more closely related than would be expected based upon their genetic diversity or due to spatial substructuring within the parasite populations. Together with previous sequential inoculation experiments, our results suggest that M. violaceum actively excludes divergent competitors while tolerating closely related genotypes. Such an exclusion mechanism might explain why multiple infections were less frequent in populations with the highest genetic diversity, which is at odds with intuitive expectations. Thus, these results demonstrate that genetic diversity can influence the prevalence of multiple infections in nature, which will have important consequences for their optimal levels of virulence. Measuring the occurrence of multiple infections and the relatedness among parasites within hosts in natural populations may be important for understanding the evolutionary dynamics of disease, the consequences of vaccine use, and forces driving the population genetic structure of parasites.
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Affiliation(s)
| | - Odile Jonot
- Univ Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, Orsay, France
- CNRS, UMR 8079, Orsay, France
| | - Amélie Coantic
- Univ Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, Orsay, France
- CNRS, UMR 8079, Orsay, France
| | - Michael E Hood
- Department of Biology, Amherst College, Amherst, Massachusetts, United States of America
| | - Jérôme Enjalbert
- Laboratoire de Pathologie Végétale, INRA BIOGER, Thiverval Grignon, France
| | - Tatiana Giraud
- Univ Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, Orsay, France
- CNRS, UMR 8079, Orsay, France
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Giraud T, Jonot O, Shykoff JA. Common sex-linked deleterious alleles in a plant parasitic fungus alter infection success but show no pleiotropic advantage. J Evol Biol 2006; 19:970-80. [PMID: 16674592 DOI: 10.1111/j.1420-9101.2005.01032.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microbotryum violaceum is a fungus that causes the sterilizing anther smut disease in Caryophyllaceae. Its diploid teliospores normally produce equal proportions of haploid sporidia of its two mating types. However natural populations contain high frequencies of individuals producing sporidia of only one mating type ('biased strains'). This mating type-ratio bias is caused by deleterious alleles at haploid phase ('haplo-lethals') linked to the mating type locus that can be transmitted only by intra-tetrad selfing. We used experimental inoculations to test some of the hypotheses proposed to explain the maintenance of haplo-lethals. We found a disadvantage of biased strains in infection ability and high intra-tetrad mating rates. Biased strains had no higher competitive ability nor shorter latency and their higher spore production per flower appeared insufficient to compensate their disadvantages. These findings were only consistent with the hypothesis that haplo-lethals are maintained under a metapopulation structure because of high intra-tetrad selfing rates, founder effects and selection at the population level.
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Affiliation(s)
- T Giraud
- Ecologie, Systématique et Evolution, UMR 8079 Université Paris Sud, Université Paris-Sud, Orsay cedex, France.
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Puustinen S, Koskela T, Mutikainen P. Relatedness affects competitive performance of a parasitic plant (Cuscuta europaea) in multiple infections. J Evol Biol 2004; 17:897-903. [PMID: 15271090 DOI: 10.1111/j.1420-9101.2004.00728.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Theoretical models predict that parasite relatedness affects the outcome of competition between parasites, and the evolution of parasite virulence. We examined whether parasite relatedness affects competition between parasitic plants (Cuscuta europaea) that share common host plants (Urtica dioica). We infected hosts with two parasitic plants that were either half-siblings or nonrelated. Relative size asymmetry between the competing parasites was significantly higher in the nonrelated infections compared to infections with siblings. This higher asymmetry was caused by the fact that the performance of some parasite genotypes decreased and that of others increased when grown in multiple infections with nonrelated parasites. This result agrees with the predictions of theories on the evolution of parasite virulence: to enhance parasite transmission, selection may favour reduced competition with genetically related parasites in hosts infected by several genotypes. However, in contrast to the most common predictions, nonrelated infections were not more virulent than the sibling infections.
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Affiliation(s)
- S Puustinen
- Department of Biology, University of Joensuu, Joensuu, Finland.
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Auclair J, Boland GJ, Kohn LM, Rajcan I. Genetic Interactions Between Glycine max and Sclerotinia sclerotiorumUsing a Straw Inoculation Method. PLANT DISEASE 2004; 88:891-895. [PMID: 30812520 DOI: 10.1094/pdis.2004.88.8.891] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Genetic interactions for disease response between cultivars of Glycine max and isolates of Scle-rotinia sclerotiorum were evaluated in controlled-environment inoculations of five soybean cultivars with four genetically unique isolates of S. sclerotiorum. The objective of this study was to identify host-pathogen interactions using isolates of the pathogen which had different geographical and crop-wise distribution as well as a different DNA-based fingerprint. To do so, 4-week-old soybean plants were inoculated with individual isolates of S. sclerotiorum using a straw inoculation method. Inoculated plants were incubated for 48 h in continuous leaf wetness and rated for disease severity 1 and 2 weeks after inoculation. Significant differences in disease severity were detected among the soybean cultivars, and NK S08-80 consistently had the lowest disease severity among the five cultivars tested. No significant differences in disease severity were observed among pathogen isolates and no significant interactions were detected between soybean cultivars and pathogen isolates. These results suggest the following interpretations: (i) either the clonal genotype of the four pathogen isolates as determined by mycelial compatibility and DNA fingerprint was not associated with level of virulence on the five soybean cultivars or (ii) the soybean cultivars themselves were not capable of revealing any differences in virulence among isolates that would be related to their genetic fingerprint or regional distribution. The results of this study are consistent with the practice of considering different isolates of S. scle-rotiorum sampled from soybean in the same geographical region as equivalent for the evaluation of soybean cultivars for resistance to Sclerotinia stem rot.
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Affiliation(s)
- J Auclair
- Graduate Research Assistant, Department of Plant Agriculture
| | - G J Boland
- Professor, Department of Environmental Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - L M Kohn
- Professor, Department of Botany, University of Toronto, Mississauga, ON, Canada L5L 156
| | - I Rajcan
- Associate Professor, Department of Plant Agriculture, University of Guelph
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Schürch S, Roy BA. Comparing single- vs. mixed-genotype infections of Mycosphaerella graminicola on wheat: effects on pathogen virulence and host tolerance. Evol Ecol 2004. [DOI: 10.1023/b:evec.0000017673.12192.3c] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Linde CC, Zhan J, McDonald BA. Population Structure of Mycosphaerella graminicola: From Lesions to Continents. PHYTOPATHOLOGY 2002; 92:946-55. [PMID: 18944019 DOI: 10.1094/phyto.2002.92.9.946] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
ABSTRACT The genetic structure of field populations of Mycosphaerella graminicola was determined across a hierarchy of spatial scales using restriction fragment length polymorphism markers. The hierarchical gene diversity analysis included 1,098 isolates from seven field populations. Spatial scales ranged from millimeters to thousands of kilometers, including comparisons within and among lesions, within and among fields, and within and among regions and continents. At the smallest spatial scale, microtransect sampling was used to determine the spatial distribution of 15 genotypes found among 158 isolates sampled from five individual lesions. Each lesion had two to six different genotypes including both mating types in four of the five lesions, but in most cases a lesion was composed of one or two genotypes that occupied the majority of the lesion, with other rare genotypes interspersed among the common genotypes. The majority (77%) of gene diversity was distributed within plots ranging from approximately 1 to 9 m(2) in size. Genotype diversity (G / N) within fields for the Swiss, Texas, and Israeli fields was high, ranging from 79 to 100% of maximum possible values. Low population differentiation was indicated by the low G(ST) values among populations, suggesting a corresponding high degree of gene flow among these populations. At the largest spatial scale, populations from Switzerland, Israel, Oregon, and Texas were compared. Population differentiation among these populations was low (G(ST) = 0.05), and genetic identity between populations was high. A low but significant correlation between genetic and geographic distance among populations was found (r = -0.47, P = 0.012), suggesting that these populations probably have not reached an equilibrium between gene flow and genetic drift. Gene flow on a regional level can be reduced by implementing strategies, such as improved stubble management that minimize the production of ascospores. The possibility of high levels of gene flow on a regional level indicates a significant potential risk for the regional spread of mutant alleles that enable fungicide resistance or the breakdown of resistance genes.
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