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Havard Kauserud - One of the best experts on this subject based on the ideXlab platform.
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High variability in a mating type linked region in the Dry Rot fungus Serpula lacrymans caused by frequency-dependent selection?
BMC Genetics, 2010Co-Authors: Ingeborg Bjorvand Engh, Inger Skrede, Glennpeter Saetre, Havard KauserudAbstract:Background The mating type loci that govern the mating process in fungi are thought to be influenced by negative frequency-dependent selection due to rare allele advantage. In this study we used a mating type linked DNA marker as a proxy to indirectly study the allelic richness and geographic distribution of mating types of one mating type locus (MAT A) in worldwide populations of the Dry Rot fungus Serpula lacrymans . This fungus, which causes serious destruction to wooden constructions in temperate regions worldwide, has recently expanded its geographic range with a concomitant genetic bottleneck. Results High allelic richness and molecular variation was detected in the mating type linked marker as compared to other presumably neutral markers. Comparable amounts of genetic variation appeared in the mating type linked marker in populations from nature and buildings, which contrast the pattern observed with neutral genetic markers where natural populations were far more variable. Some geographic structuring of the allelic variation in the mating type linked marker appeared, but far less than that observed with neutral markers. In founder populations of S. lacrymans , alleles co-occurring in heterokaryotic individuals were more divergent than expected by chance, which agrees with the expectation for populations where few mating alleles exists. The analyzed DNA marker displays trans-species polymorphism wherein some alleles from the closely related species S. himantoides are more similar to those of S. lacrymans than other alleles from S. himantoides . Conclusions Our results support the idea that strong negative frequency-dependent selection maintains high levels of genetic variation in MAT-linked genomic regions, even in recently bottlenecked populations of S. lacrymans .
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high variability in a mating type linked region in the Dry Rot fungus serpula lacrymans caused by frequency dependent selection
BMC Genetics, 2010Co-Authors: Ingeborg Bjorvand Engh, Inger Skrede, Glennpeter Saetre, Havard KauserudAbstract:The mating type loci that govern the mating process in fungi are thought to be influenced by negative frequency-dependent selection due to rare allele advantage. In this study we used a mating type linked DNA marker as a proxy to indirectly study the allelic richness and geographic distribution of mating types of one mating type locus (MAT A) in worldwide populations of the Dry Rot fungus Serpula lacrymans. This fungus, which causes serious destruction to wooden constructions in temperate regions worldwide, has recently expanded its geographic range with a concomitant genetic bottleneck. High allelic richness and molecular variation was detected in the mating type linked marker as compared to other presumably neutral markers. Comparable amounts of genetic variation appeared in the mating type linked marker in populations from nature and buildings, which contrast the pattern observed with neutral genetic markers where natural populations were far more variable. Some geographic structuring of the allelic variation in the mating type linked marker appeared, but far less than that observed with neutral markers. In founder populations of S. lacrymans, alleles co-occurring in heterokaryotic individuals were more divergent than expected by chance, which agrees with the expectation for populations where few mating alleles exists. The analyzed DNA marker displays trans-species polymorphism wherein some alleles from the closely related species S. himantoides are more similar to those of S. lacrymans than other alleles from S. himantoides. Our results support the idea that strong negative frequency-dependent selection maintains high levels of genetic variation in MAT-linked genomic regions, even in recently bottlenecked populations of S. lacrymans.
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asian origin and rapid global spread of the destructive Dry Rot fungus serpula lacrymans
Molecular Ecology, 2007Co-Authors: Havard Kauserud, Ingeborg Bjorvand Svegarden, Glennpeter Saetre, Henning Knudsen, Oyvind Stensrud, Olaf Schmidt, Shuichi Doi, Tomoaki Sugiyama, Nils HogbergAbstract:The Dry Rot fungus Serpula lacrymans (Basidiomycota) is the most damaging destroyer of wood construction materials in temperate regions. While being a widespread aggressive indoor biodeterioration agent, it is only found in a few natural environments. The geographical source of spread and colonization by this fungus in human environments is thus somewhat of an enigma. Employing genetic markers (amplified fragment length polymorphisms, DNA sequences and microsatellites) on a worldwide sample of specimens, we show that the Dry Rot fungus is divided into two main lineages; one nonaggressive residing naturally in North America and Asia (var. shastensis), and another aggressive lineage including specimens from all continents, both from natural environments and buildings (var. lacrymans). Our genetic analyses indicate that the two lineages represent well-differentiated cryptic species. Genetic analyses pinpoint mainland Asia as the origin of the aggressive form var. lacrymans. A few aggressive genotypes have migrated worldwide from Asia to Europe, North and South America and Oceania followed by local population expansions. The very low genetic variation in the founder populations indicate that they have established through recent founder events, for example by infected wood materials transported over land or sea. A separate colonization has happened from mainland Asia to Japan. Our data also indicate that independent immigration events have happened to Oceania from different continents followed by admixture.
Pavani Tumbalam - One of the best experts on this subject based on the ideXlab platform.
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first report of fusarium torulosum causing Dry Rot of seed potato tubers in the united states
Plant Disease, 2011Co-Authors: Esther Gachango, W W Kirk, Linda E Hanson, Alejandro Rojas, Pavani TumbalamAbstract:Fusarium Dry Rot of potato (Solanum tuberosum L.) is a postharvest disease caused by several Fusarium species and is of worldwide importance. Thirteen species of Fusarium have been implicated in fungal Dry Rots of potatoes worldwide. Among them, eight species have been reported in the northern United States (2). In Michigan potato production, F. sambucinum was the predominant species reported to be affecting seed potato in storage and causing seed piece decay after planting (3). Some previous identifications of F. sambucinum as Dry Rot may have been F. torulosum since F. torulosum was previously classified within F. sambucinum (4). To further investigate this, Dry Rot symptomatic tubers were collected from Michigan seed lots in the summers of 2009 and 2010. Small sections from the margins of necRotic regions were cut with a scalpel, surface sterilized in 0.5% sodium hypochlorite for 10 s, rinsed twice in sterile distilled water, and blotted with sterile filter paper. The tissue pieces were plated on half-...
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First report of potato tuber sprout Rot caused by Fusarium sambucinum in Michigan.
Plant disease, 2006Co-Authors: P. S. Wharton, Pavani Tumbalam, William W. KirkAbstract:Fusarium Dry Rot is one of the most important diseases of potato (Solanum tuberosum L.), affecting tubers in storage and whole seed or seed pieces after planting (2). Fusarium sambucinum Fuckel (teleomorph Giberella pulicaris) is the most common pathogen causing Dry Rot of stored tubers in North America. (4). Cut seed potato tubers of cvs. FL1879 and Pike with severe sprout Rot were collected in Michigan during May 2006. As well as having Rotted sprouts, all diseased tubers had Dry Rot. When diseased sprouts were cut in half, brown, necRotic lesions could be seen spreading down the center of the sprout in vascular tissue and at the base of the sprout in tuber tissue. Pathogen isolations were made from both infected tuber tissue and diseased sprouts on potato dextrose agar (PDA). In both cases, only F. sambucinum was isolated from diseased sprout and tuber tissue. Identification of the pathogen was based on colony and conidial morphology. This included white, fluffy mycelium on the surface and crimson coloration of the colonies viewed from the underside of PDA plates and large distinctive macroconidia (3). Identification was confirmed by comparison of ITS (internal transcribed spacer) sequence data with reference isolates. The ITS region of rDNA was amplified by polymerase chain reaction (PCR) with primers ITS1/ITS4 and sequenced. BLASTn analysis (1) of the sequence obtained showed a 100% homology with F. sambucinum Fuckel. For inoculum production, isolates were grown on PDA at 8°C for 14 days prior to inoculation. Pathogenicity was tested in potato tubers of cv. FL1879 with a single isolate collected from diseased sprouts. Whole seed tubers with 4 mm long sprouts were cut in half longitudinally with a sterile knife to ensure that seed pieces had viable sprouts. The cut surfaces of seed pieces were spray inoculated with 200 ml of conidial suspension (1 × 104 conidia ml-1) over the entire cut surface to give a final dosage of approximately 1 ml per seed piece. Care was taken to limit inoculum spray to the cut surface so that sprouts were not inoculated. Seed pieces (40 per replicate × 4 replicates) were then placed in plastic boxes (30 × 15 × 10 cm) and incubated in the dark at 18°C and 95% relative humidity for 30 days in a controlled environment chamber. As a control, cut seed pieces were spayed with sterile distilled water and incubated as above. All tubers inoculated with the pathogen developed typical Fusarium Dry Rot symptoms consisting of a brown, Dry decay of tuber tissue with mycelial lined cavities. Sprouts on inoculated tubers developed symptoms that were observed in the initially collected seed pieces, and F. sambucinum was reisolated from all infected sprouts. The noninoculated control tubers did not develop any symptoms of Dry Rot. The results of the pathogenicity tests indicate that F. sambucinum caused sprout Rot on potato seed pieces. Since only the cut surfaces of tubers were inoculated, it is assumed that infection of sprouts is systemic through the tuber. To our knowledge, this is the first report of F. sambucinum causing a sprout Rot of developing sprouts on seed tubers in the United States. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) L. E. Hanson et al. Phytopathology 86:378, 1996. (3) P. E. Nelson et al. Pages 118-119 in: Fusarium Species: An Illustrated Manual for Identification. The Pennsylvania State University, University Park and London, 1983. (4) G. A. Secor and B. Salas. Fusarium Dry Rot and Fusarium wilt. Pages 23-25 in: Compendium of Potato Diseases. 2nd ed. W. R. Stevenson et al., eds. The American Phytopathological Society, St. Paul, MN, 2001.
Glennpeter Saetre - One of the best experts on this subject based on the ideXlab platform.
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High variability in a mating type linked region in the Dry Rot fungus Serpula lacrymans caused by frequency-dependent selection?
BMC Genetics, 2010Co-Authors: Ingeborg Bjorvand Engh, Inger Skrede, Glennpeter Saetre, Havard KauserudAbstract:Background The mating type loci that govern the mating process in fungi are thought to be influenced by negative frequency-dependent selection due to rare allele advantage. In this study we used a mating type linked DNA marker as a proxy to indirectly study the allelic richness and geographic distribution of mating types of one mating type locus (MAT A) in worldwide populations of the Dry Rot fungus Serpula lacrymans . This fungus, which causes serious destruction to wooden constructions in temperate regions worldwide, has recently expanded its geographic range with a concomitant genetic bottleneck. Results High allelic richness and molecular variation was detected in the mating type linked marker as compared to other presumably neutral markers. Comparable amounts of genetic variation appeared in the mating type linked marker in populations from nature and buildings, which contrast the pattern observed with neutral genetic markers where natural populations were far more variable. Some geographic structuring of the allelic variation in the mating type linked marker appeared, but far less than that observed with neutral markers. In founder populations of S. lacrymans , alleles co-occurring in heterokaryotic individuals were more divergent than expected by chance, which agrees with the expectation for populations where few mating alleles exists. The analyzed DNA marker displays trans-species polymorphism wherein some alleles from the closely related species S. himantoides are more similar to those of S. lacrymans than other alleles from S. himantoides . Conclusions Our results support the idea that strong negative frequency-dependent selection maintains high levels of genetic variation in MAT-linked genomic regions, even in recently bottlenecked populations of S. lacrymans .
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high variability in a mating type linked region in the Dry Rot fungus serpula lacrymans caused by frequency dependent selection
BMC Genetics, 2010Co-Authors: Ingeborg Bjorvand Engh, Inger Skrede, Glennpeter Saetre, Havard KauserudAbstract:The mating type loci that govern the mating process in fungi are thought to be influenced by negative frequency-dependent selection due to rare allele advantage. In this study we used a mating type linked DNA marker as a proxy to indirectly study the allelic richness and geographic distribution of mating types of one mating type locus (MAT A) in worldwide populations of the Dry Rot fungus Serpula lacrymans. This fungus, which causes serious destruction to wooden constructions in temperate regions worldwide, has recently expanded its geographic range with a concomitant genetic bottleneck. High allelic richness and molecular variation was detected in the mating type linked marker as compared to other presumably neutral markers. Comparable amounts of genetic variation appeared in the mating type linked marker in populations from nature and buildings, which contrast the pattern observed with neutral genetic markers where natural populations were far more variable. Some geographic structuring of the allelic variation in the mating type linked marker appeared, but far less than that observed with neutral markers. In founder populations of S. lacrymans, alleles co-occurring in heterokaryotic individuals were more divergent than expected by chance, which agrees with the expectation for populations where few mating alleles exists. The analyzed DNA marker displays trans-species polymorphism wherein some alleles from the closely related species S. himantoides are more similar to those of S. lacrymans than other alleles from S. himantoides. Our results support the idea that strong negative frequency-dependent selection maintains high levels of genetic variation in MAT-linked genomic regions, even in recently bottlenecked populations of S. lacrymans.
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asian origin and rapid global spread of the destructive Dry Rot fungus serpula lacrymans
Molecular Ecology, 2007Co-Authors: Havard Kauserud, Ingeborg Bjorvand Svegarden, Glennpeter Saetre, Henning Knudsen, Oyvind Stensrud, Olaf Schmidt, Shuichi Doi, Tomoaki Sugiyama, Nils HogbergAbstract:The Dry Rot fungus Serpula lacrymans (Basidiomycota) is the most damaging destroyer of wood construction materials in temperate regions. While being a widespread aggressive indoor biodeterioration agent, it is only found in a few natural environments. The geographical source of spread and colonization by this fungus in human environments is thus somewhat of an enigma. Employing genetic markers (amplified fragment length polymorphisms, DNA sequences and microsatellites) on a worldwide sample of specimens, we show that the Dry Rot fungus is divided into two main lineages; one nonaggressive residing naturally in North America and Asia (var. shastensis), and another aggressive lineage including specimens from all continents, both from natural environments and buildings (var. lacrymans). Our genetic analyses indicate that the two lineages represent well-differentiated cryptic species. Genetic analyses pinpoint mainland Asia as the origin of the aggressive form var. lacrymans. A few aggressive genotypes have migrated worldwide from Asia to Europe, North and South America and Oceania followed by local population expansions. The very low genetic variation in the founder populations indicate that they have established through recent founder events, for example by infected wood materials transported over land or sea. A separate colonization has happened from mainland Asia to Japan. Our data also indicate that independent immigration events have happened to Oceania from different continents followed by admixture.
Ingeborg Bjorvand Engh - One of the best experts on this subject based on the ideXlab platform.
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high variability in a mating type linked region in the Dry Rot fungus serpula lacrymans caused by frequency dependent selection
BMC Genetics, 2010Co-Authors: Ingeborg Bjorvand Engh, Inger Skrede, Glennpeter Saetre, Havard KauserudAbstract:The mating type loci that govern the mating process in fungi are thought to be influenced by negative frequency-dependent selection due to rare allele advantage. In this study we used a mating type linked DNA marker as a proxy to indirectly study the allelic richness and geographic distribution of mating types of one mating type locus (MAT A) in worldwide populations of the Dry Rot fungus Serpula lacrymans. This fungus, which causes serious destruction to wooden constructions in temperate regions worldwide, has recently expanded its geographic range with a concomitant genetic bottleneck. High allelic richness and molecular variation was detected in the mating type linked marker as compared to other presumably neutral markers. Comparable amounts of genetic variation appeared in the mating type linked marker in populations from nature and buildings, which contrast the pattern observed with neutral genetic markers where natural populations were far more variable. Some geographic structuring of the allelic variation in the mating type linked marker appeared, but far less than that observed with neutral markers. In founder populations of S. lacrymans, alleles co-occurring in heterokaryotic individuals were more divergent than expected by chance, which agrees with the expectation for populations where few mating alleles exists. The analyzed DNA marker displays trans-species polymorphism wherein some alleles from the closely related species S. himantoides are more similar to those of S. lacrymans than other alleles from S. himantoides. Our results support the idea that strong negative frequency-dependent selection maintains high levels of genetic variation in MAT-linked genomic regions, even in recently bottlenecked populations of S. lacrymans.
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High variability in a mating type linked region in the Dry Rot fungus Serpula lacrymans caused by frequency-dependent selection?
BMC Genetics, 2010Co-Authors: Ingeborg Bjorvand Engh, Inger Skrede, Glennpeter Saetre, Havard KauserudAbstract:Background The mating type loci that govern the mating process in fungi are thought to be influenced by negative frequency-dependent selection due to rare allele advantage. In this study we used a mating type linked DNA marker as a proxy to indirectly study the allelic richness and geographic distribution of mating types of one mating type locus (MAT A) in worldwide populations of the Dry Rot fungus Serpula lacrymans . This fungus, which causes serious destruction to wooden constructions in temperate regions worldwide, has recently expanded its geographic range with a concomitant genetic bottleneck. Results High allelic richness and molecular variation was detected in the mating type linked marker as compared to other presumably neutral markers. Comparable amounts of genetic variation appeared in the mating type linked marker in populations from nature and buildings, which contrast the pattern observed with neutral genetic markers where natural populations were far more variable. Some geographic structuring of the allelic variation in the mating type linked marker appeared, but far less than that observed with neutral markers. In founder populations of S. lacrymans , alleles co-occurring in heterokaryotic individuals were more divergent than expected by chance, which agrees with the expectation for populations where few mating alleles exists. The analyzed DNA marker displays trans-species polymorphism wherein some alleles from the closely related species S. himantoides are more similar to those of S. lacrymans than other alleles from S. himantoides . Conclusions Our results support the idea that strong negative frequency-dependent selection maintains high levels of genetic variation in MAT-linked genomic regions, even in recently bottlenecked populations of S. lacrymans .
William W. Kirk - One of the best experts on this subject based on the ideXlab platform.
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First report of potato tuber sprout Rot caused by Fusarium sambucinum in Michigan.
Plant disease, 2006Co-Authors: P. S. Wharton, Pavani Tumbalam, William W. KirkAbstract:Fusarium Dry Rot is one of the most important diseases of potato (Solanum tuberosum L.), affecting tubers in storage and whole seed or seed pieces after planting (2). Fusarium sambucinum Fuckel (teleomorph Giberella pulicaris) is the most common pathogen causing Dry Rot of stored tubers in North America. (4). Cut seed potato tubers of cvs. FL1879 and Pike with severe sprout Rot were collected in Michigan during May 2006. As well as having Rotted sprouts, all diseased tubers had Dry Rot. When diseased sprouts were cut in half, brown, necRotic lesions could be seen spreading down the center of the sprout in vascular tissue and at the base of the sprout in tuber tissue. Pathogen isolations were made from both infected tuber tissue and diseased sprouts on potato dextrose agar (PDA). In both cases, only F. sambucinum was isolated from diseased sprout and tuber tissue. Identification of the pathogen was based on colony and conidial morphology. This included white, fluffy mycelium on the surface and crimson coloration of the colonies viewed from the underside of PDA plates and large distinctive macroconidia (3). Identification was confirmed by comparison of ITS (internal transcribed spacer) sequence data with reference isolates. The ITS region of rDNA was amplified by polymerase chain reaction (PCR) with primers ITS1/ITS4 and sequenced. BLASTn analysis (1) of the sequence obtained showed a 100% homology with F. sambucinum Fuckel. For inoculum production, isolates were grown on PDA at 8°C for 14 days prior to inoculation. Pathogenicity was tested in potato tubers of cv. FL1879 with a single isolate collected from diseased sprouts. Whole seed tubers with 4 mm long sprouts were cut in half longitudinally with a sterile knife to ensure that seed pieces had viable sprouts. The cut surfaces of seed pieces were spray inoculated with 200 ml of conidial suspension (1 × 104 conidia ml-1) over the entire cut surface to give a final dosage of approximately 1 ml per seed piece. Care was taken to limit inoculum spray to the cut surface so that sprouts were not inoculated. Seed pieces (40 per replicate × 4 replicates) were then placed in plastic boxes (30 × 15 × 10 cm) and incubated in the dark at 18°C and 95% relative humidity for 30 days in a controlled environment chamber. As a control, cut seed pieces were spayed with sterile distilled water and incubated as above. All tubers inoculated with the pathogen developed typical Fusarium Dry Rot symptoms consisting of a brown, Dry decay of tuber tissue with mycelial lined cavities. Sprouts on inoculated tubers developed symptoms that were observed in the initially collected seed pieces, and F. sambucinum was reisolated from all infected sprouts. The noninoculated control tubers did not develop any symptoms of Dry Rot. The results of the pathogenicity tests indicate that F. sambucinum caused sprout Rot on potato seed pieces. Since only the cut surfaces of tubers were inoculated, it is assumed that infection of sprouts is systemic through the tuber. To our knowledge, this is the first report of F. sambucinum causing a sprout Rot of developing sprouts on seed tubers in the United States. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) L. E. Hanson et al. Phytopathology 86:378, 1996. (3) P. E. Nelson et al. Pages 118-119 in: Fusarium Species: An Illustrated Manual for Identification. The Pennsylvania State University, University Park and London, 1983. (4) G. A. Secor and B. Salas. Fusarium Dry Rot and Fusarium wilt. Pages 23-25 in: Compendium of Potato Diseases. 2nd ed. W. R. Stevenson et al., eds. The American Phytopathological Society, St. Paul, MN, 2001.
