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Stephen E Strelkov - One of the best experts on this subject based on the ideXlab platform.
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clubroot resistance derived from the european brassica napus cv tosca is not effective against virulent plasmodiophora brassicae isolates from alberta canada
Scientific Reports, 2021Co-Authors: Rudolph Freduaagyeman, Sheaufang Hwang, Hui Zhang, Igor Falak, Xiuqiang Huang, Stephen E StrelkovAbstract:In this study, clubroot resistance in the resynthesized European winter Brassica napus cv. ‘Tosca’ was introgressed into a Canadian spring canola line ‘11SR0099’, which was then crossed with the clubroot susceptible spring line ‘12DH0001’ to produce F1 seeds. The F1 plants were used to develop a doubled haploid (DH) mapping population. The parents and the DH lines were screened against ‘old’ Pathotypes 2F, 3H, 5I, 6M and 8N of the clubroot pathogen, Plasmodiophora brassicae, as well as against the ‘new’ Pathotypes 5X, 5L, 2B, 3A, 3D, 5G, 8E, 5C, 8J, 5K, 3O and 8P. Genotyping was conducted using a Brassica 15K SNP array. The clubroot screening showed that ‘Tosca, ‘11SR0099’ and the resistant DH lines were resistant to three (2F, 3H and 5I) of the five ‘old’ Pathotypes and four (2B, 3O, 8E and 8P) of the 12 ‘new’ Pathotypes, while being moderately resistant to the ‘old’ pathotype 8N and the ‘new’ Pathotypes 3D and 5G. ‘Tosca’ was susceptible to isolates representing pathotype 3A (the most common among the ‘new’ Pathotypes) as well as Pathotypes 6M, 5X, 5L, 5K and 8J. Linkage analysis and QTL mapping identified a ca. 0.88–0.95 Mb genomic region on the A03 chromosome of ‘Tosca’ as conferring resistance to Pathotypes 2F, 3H, 5I, 2B, 3D, 5G, 8E, 3O and 8P. The identified QTL genomic region housed the CRk, Crr3 and CRd gene(s). However, the susceptibility of ‘Tosca’ to most of the common virulent Pathotypes makes it unattractive as a sole CR donor in the breeding of commercial canola varieties in western Canada.
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Clubroot resistance derived from the European Brassica napus cv. ‘Tosca’ is not effective against virulent Plasmodiophora brassicae isolates from Alberta, Canada
'Springer Science and Business Media LLC', 2021Co-Authors: Rudolph Fredua-agyeman, Sheaufang Hwang, Hui Zhang, Igor Falak, Xiuqiang Huang, Stephen E StrelkovAbstract:Abstract In this study, clubroot resistance in the resynthesized European winter Brassica napus cv. ‘Tosca’ was introgressed into a Canadian spring canola line ‘11SR0099’, which was then crossed with the clubroot susceptible spring line ‘12DH0001’ to produce F1 seeds. The F1 plants were used to develop a doubled haploid (DH) mapping population. The parents and the DH lines were screened against ‘old’ Pathotypes 2F, 3H, 5I, 6M and 8N of the clubroot pathogen, Plasmodiophora brassicae, as well as against the ‘new’ Pathotypes 5X, 5L, 2B, 3A, 3D, 5G, 8E, 5C, 8J, 5K, 3O and 8P. Genotyping was conducted using a Brassica 15K SNP array. The clubroot screening showed that ‘Tosca, ‘11SR0099’ and the resistant DH lines were resistant to three (2F, 3H and 5I) of the five ‘old’ Pathotypes and four (2B, 3O, 8E and 8P) of the 12 ‘new’ Pathotypes, while being moderately resistant to the ‘old’ pathotype 8N and the ‘new’ Pathotypes 3D and 5G. ‘Tosca’ was susceptible to isolates representing pathotype 3A (the most common among the ‘new’ Pathotypes) as well as Pathotypes 6M, 5X, 5L, 5K and 8J. Linkage analysis and QTL mapping identified a ca. 0.88–0.95 Mb genomic region on the A03 chromosome of ‘Tosca’ as conferring resistance to Pathotypes 2F, 3H, 5I, 2B, 3D, 5G, 8E, 3O and 8P. The identified QTL genomic region housed the CRk, Crr3 and CRd gene(s). However, the susceptibility of ‘Tosca’ to most of the common virulent Pathotypes makes it unattractive as a sole CR donor in the breeding of commercial canola varieties in western Canada
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virulence spectrum of single spore and field isolates of plasmodiophora brassicae able to overcome resistance in canola brassica napus
Plant Disease, 2021Co-Authors: Homa Askarian, Sheaufang Hwang, Tiesen Cao, Victor P. Manolii, Alireza Akhavan, Stephen E StrelkovAbstract:Clubroot, caused by Plasmodiophora brassicae Woronin, is an important disease of canola (Brassica napus L.) that is managed mainly by planting clubroot-resistant (CR) cultivars. Field isolates of P. brassicae can be heterogeneous mixtures of various Pathotypes, making assessments of the genetics of host-pathogen interactions challenging. Thirty-four single-spore isolates were obtained from nine field isolates of the pathogen collected from CR canola cultivars. The virulence patterns of the single-spore and field isolates were assessed on the 13 host genotypes of the Canadian Clubroot Differential (CCD) set, which includes the differentials of Williams and Some et al. Indices of disease (IDs) severity of 25, 33, and 50% (±95% confidence interval) were compared as potential thresholds to distinguish between resistant and susceptible reactions, with an ID of 50% giving the most consistent responses for pathotype classification purposes. With this threshold, 13 Pathotypes could be distinguished based on the CCD system, 7 on the differentials of Williams, and 3 on the hosts of Some et al. The highest correlations were observed among virulence matrices generated using the three threshold IDs on the CCD set. Genetically homogeneous single-spore isolates gave a clearer profile of the P. brassicae pathotype structure. Novel Pathotypes, not reported in Canada previously, were identified among the isolates. This large collection of single-spore isolates can serve as a reference in screening and breeding for clubroot resistance.
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Virulence and pathotype classification of Plasmodiophora brassicae populations collected from clubroot resistant canola (Brassica napus) in Canada
2018Co-Authors: Stephen E Strelkov, Sheaufang Hwang, Tiesen Cao, Rudolph Fredua-agyeman, Victor P. Manolii, Michael W. Harding, Gary Peng, Bruce D. Gossen, Mary Ruth Mcdonald, David FeindelAbstract:Clubroot, caused by Plasmodiophora brassicae Wor., is an important soilborne disease of canola (Brassica napus L.) in Canada that is managed mainly by planting clubroot-resistant (CR) cultivars. Populations of P. brassicae representing 106 fields in Alberta were obtained from galled roots of CR canola plants collected in 2014–2016 and characterized for virulence on seven CR canola cultivars. Sixty-one of these populations could overcome resistance in at least one CR cultivar and were evaluated further by inoculation on 13 Brassica hosts termed the Canadian Clubroot Differential (CCD) Set. The CCD Set included the differentials of Williams and Somé et al., selected hosts of the European Clubroot Differential Set, and the B. napus cultivars ‘Brutor’, ‘Mendel’, ‘Westar’ and ‘45H29’. Each unique virulence pattern on the CCD Set represented a distinct pathotype and was identified with a letter. Five reference isolates, obtained prior to the introduction of CR canola, also were assessed. A total of 17 Pathotypes were detected using the CCD Set, compared with five Pathotypes using the system of Williams and two with the system of Somé et al., suggesting that the CCD Set has a greater differentiating capacity. Pathotype A, a variant of pathotype 3 (as per Williams) which is able to overcome the resistance in CR B. napus, was predominant. The original pathotype 3, which is avirulent on CR canola, was classified as CCD pathotype H. An integrated strategy, combining other tools in addition to resistance, will be needed for the sustainable management of clubroot.
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resistance to plasmodiophora brassicae in brassica rapa and brassica juncea genotypes from china
Plant Disease, 2015Co-Authors: Hui Zhang, Stephen E Strelkov, Jie Feng, Shujiang Zhang, Shifan Zhang, Rifei Sun, Sheaufang HwangAbstract:Clubroot disease, caused by Plasmodiophora brassicae Woronin, has become a major problem in cruciferous crops worldwide. Chinese cabbage (Brassica rapa), pak choi (B. rapa), and mustard (B. juncea) are important vegetable crops in China. Development of clubroot-resistant cultivars of these crops is urgently needed. In this study, 71 B. rapa and B. juncea genotypes from China, including cultivars and inbred lines, were evaluated for resistance to three P. brassicae Pathotypes. A significant interaction was observed between the P. brassicae Pathotypes and the Brassica genotypes. Pathotype 3, as defined on the differentials of Williams, exhibited the weakest virulence on all plant material. By contrast, Pathotypes 5 and 6 were both highly pathogenic on most of the tested genotypes. In all, 10 of the 14 Chinese cabbage cultivars were resistant to all three Pathotypes, while 4 were resistant only to a specific pathotype. Seven of eight progenies obtained from the selfing of Chinese cabbage cultivars were resistant to pathotype 3 but most were susceptible to Pathotypes 5 and 6. Most inbred lines of Chinese cabbage and all inbred lines of pak choi and mustard were susceptible to all three Pathotypes but their susceptibility was lower to pathotype 3 than to Pathotypes 5 and 6.
Sheaufang Hwang - One of the best experts on this subject based on the ideXlab platform.
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clubroot resistance derived from the european brassica napus cv tosca is not effective against virulent plasmodiophora brassicae isolates from alberta canada
Scientific Reports, 2021Co-Authors: Rudolph Freduaagyeman, Sheaufang Hwang, Hui Zhang, Igor Falak, Xiuqiang Huang, Stephen E StrelkovAbstract:In this study, clubroot resistance in the resynthesized European winter Brassica napus cv. ‘Tosca’ was introgressed into a Canadian spring canola line ‘11SR0099’, which was then crossed with the clubroot susceptible spring line ‘12DH0001’ to produce F1 seeds. The F1 plants were used to develop a doubled haploid (DH) mapping population. The parents and the DH lines were screened against ‘old’ Pathotypes 2F, 3H, 5I, 6M and 8N of the clubroot pathogen, Plasmodiophora brassicae, as well as against the ‘new’ Pathotypes 5X, 5L, 2B, 3A, 3D, 5G, 8E, 5C, 8J, 5K, 3O and 8P. Genotyping was conducted using a Brassica 15K SNP array. The clubroot screening showed that ‘Tosca, ‘11SR0099’ and the resistant DH lines were resistant to three (2F, 3H and 5I) of the five ‘old’ Pathotypes and four (2B, 3O, 8E and 8P) of the 12 ‘new’ Pathotypes, while being moderately resistant to the ‘old’ pathotype 8N and the ‘new’ Pathotypes 3D and 5G. ‘Tosca’ was susceptible to isolates representing pathotype 3A (the most common among the ‘new’ Pathotypes) as well as Pathotypes 6M, 5X, 5L, 5K and 8J. Linkage analysis and QTL mapping identified a ca. 0.88–0.95 Mb genomic region on the A03 chromosome of ‘Tosca’ as conferring resistance to Pathotypes 2F, 3H, 5I, 2B, 3D, 5G, 8E, 3O and 8P. The identified QTL genomic region housed the CRk, Crr3 and CRd gene(s). However, the susceptibility of ‘Tosca’ to most of the common virulent Pathotypes makes it unattractive as a sole CR donor in the breeding of commercial canola varieties in western Canada.
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Clubroot resistance derived from the European Brassica napus cv. ‘Tosca’ is not effective against virulent Plasmodiophora brassicae isolates from Alberta, Canada
'Springer Science and Business Media LLC', 2021Co-Authors: Rudolph Fredua-agyeman, Sheaufang Hwang, Hui Zhang, Igor Falak, Xiuqiang Huang, Stephen E StrelkovAbstract:Abstract In this study, clubroot resistance in the resynthesized European winter Brassica napus cv. ‘Tosca’ was introgressed into a Canadian spring canola line ‘11SR0099’, which was then crossed with the clubroot susceptible spring line ‘12DH0001’ to produce F1 seeds. The F1 plants were used to develop a doubled haploid (DH) mapping population. The parents and the DH lines were screened against ‘old’ Pathotypes 2F, 3H, 5I, 6M and 8N of the clubroot pathogen, Plasmodiophora brassicae, as well as against the ‘new’ Pathotypes 5X, 5L, 2B, 3A, 3D, 5G, 8E, 5C, 8J, 5K, 3O and 8P. Genotyping was conducted using a Brassica 15K SNP array. The clubroot screening showed that ‘Tosca, ‘11SR0099’ and the resistant DH lines were resistant to three (2F, 3H and 5I) of the five ‘old’ Pathotypes and four (2B, 3O, 8E and 8P) of the 12 ‘new’ Pathotypes, while being moderately resistant to the ‘old’ pathotype 8N and the ‘new’ Pathotypes 3D and 5G. ‘Tosca’ was susceptible to isolates representing pathotype 3A (the most common among the ‘new’ Pathotypes) as well as Pathotypes 6M, 5X, 5L, 5K and 8J. Linkage analysis and QTL mapping identified a ca. 0.88–0.95 Mb genomic region on the A03 chromosome of ‘Tosca’ as conferring resistance to Pathotypes 2F, 3H, 5I, 2B, 3D, 5G, 8E, 3O and 8P. The identified QTL genomic region housed the CRk, Crr3 and CRd gene(s). However, the susceptibility of ‘Tosca’ to most of the common virulent Pathotypes makes it unattractive as a sole CR donor in the breeding of commercial canola varieties in western Canada
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virulence spectrum of single spore and field isolates of plasmodiophora brassicae able to overcome resistance in canola brassica napus
Plant Disease, 2021Co-Authors: Homa Askarian, Sheaufang Hwang, Tiesen Cao, Victor P. Manolii, Alireza Akhavan, Stephen E StrelkovAbstract:Clubroot, caused by Plasmodiophora brassicae Woronin, is an important disease of canola (Brassica napus L.) that is managed mainly by planting clubroot-resistant (CR) cultivars. Field isolates of P. brassicae can be heterogeneous mixtures of various Pathotypes, making assessments of the genetics of host-pathogen interactions challenging. Thirty-four single-spore isolates were obtained from nine field isolates of the pathogen collected from CR canola cultivars. The virulence patterns of the single-spore and field isolates were assessed on the 13 host genotypes of the Canadian Clubroot Differential (CCD) set, which includes the differentials of Williams and Some et al. Indices of disease (IDs) severity of 25, 33, and 50% (±95% confidence interval) were compared as potential thresholds to distinguish between resistant and susceptible reactions, with an ID of 50% giving the most consistent responses for pathotype classification purposes. With this threshold, 13 Pathotypes could be distinguished based on the CCD system, 7 on the differentials of Williams, and 3 on the hosts of Some et al. The highest correlations were observed among virulence matrices generated using the three threshold IDs on the CCD set. Genetically homogeneous single-spore isolates gave a clearer profile of the P. brassicae pathotype structure. Novel Pathotypes, not reported in Canada previously, were identified among the isolates. This large collection of single-spore isolates can serve as a reference in screening and breeding for clubroot resistance.
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Virulence and pathotype classification of Plasmodiophora brassicae populations collected from clubroot resistant canola (Brassica napus) in Canada
2018Co-Authors: Stephen E Strelkov, Sheaufang Hwang, Tiesen Cao, Rudolph Fredua-agyeman, Victor P. Manolii, Michael W. Harding, Gary Peng, Bruce D. Gossen, Mary Ruth Mcdonald, David FeindelAbstract:Clubroot, caused by Plasmodiophora brassicae Wor., is an important soilborne disease of canola (Brassica napus L.) in Canada that is managed mainly by planting clubroot-resistant (CR) cultivars. Populations of P. brassicae representing 106 fields in Alberta were obtained from galled roots of CR canola plants collected in 2014–2016 and characterized for virulence on seven CR canola cultivars. Sixty-one of these populations could overcome resistance in at least one CR cultivar and were evaluated further by inoculation on 13 Brassica hosts termed the Canadian Clubroot Differential (CCD) Set. The CCD Set included the differentials of Williams and Somé et al., selected hosts of the European Clubroot Differential Set, and the B. napus cultivars ‘Brutor’, ‘Mendel’, ‘Westar’ and ‘45H29’. Each unique virulence pattern on the CCD Set represented a distinct pathotype and was identified with a letter. Five reference isolates, obtained prior to the introduction of CR canola, also were assessed. A total of 17 Pathotypes were detected using the CCD Set, compared with five Pathotypes using the system of Williams and two with the system of Somé et al., suggesting that the CCD Set has a greater differentiating capacity. Pathotype A, a variant of pathotype 3 (as per Williams) which is able to overcome the resistance in CR B. napus, was predominant. The original pathotype 3, which is avirulent on CR canola, was classified as CCD pathotype H. An integrated strategy, combining other tools in addition to resistance, will be needed for the sustainable management of clubroot.
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resistance to plasmodiophora brassicae in brassica rapa and brassica juncea genotypes from china
Plant Disease, 2015Co-Authors: Hui Zhang, Stephen E Strelkov, Jie Feng, Shujiang Zhang, Shifan Zhang, Rifei Sun, Sheaufang HwangAbstract:Clubroot disease, caused by Plasmodiophora brassicae Woronin, has become a major problem in cruciferous crops worldwide. Chinese cabbage (Brassica rapa), pak choi (B. rapa), and mustard (B. juncea) are important vegetable crops in China. Development of clubroot-resistant cultivars of these crops is urgently needed. In this study, 71 B. rapa and B. juncea genotypes from China, including cultivars and inbred lines, were evaluated for resistance to three P. brassicae Pathotypes. A significant interaction was observed between the P. brassicae Pathotypes and the Brassica genotypes. Pathotype 3, as defined on the differentials of Williams, exhibited the weakest virulence on all plant material. By contrast, Pathotypes 5 and 6 were both highly pathogenic on most of the tested genotypes. In all, 10 of the 14 Chinese cabbage cultivars were resistant to all three Pathotypes, while 4 were resistant only to a specific pathotype. Seven of eight progenies obtained from the selfing of Chinese cabbage cultivars were resistant to pathotype 3 but most were susceptible to Pathotypes 5 and 6. Most inbred lines of Chinese cabbage and all inbred lines of pak choi and mustard were susceptible to all three Pathotypes but their susceptibility was lower to pathotype 3 than to Pathotypes 5 and 6.
Hui Zhang - One of the best experts on this subject based on the ideXlab platform.
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clubroot resistance derived from the european brassica napus cv tosca is not effective against virulent plasmodiophora brassicae isolates from alberta canada
Scientific Reports, 2021Co-Authors: Rudolph Freduaagyeman, Sheaufang Hwang, Hui Zhang, Igor Falak, Xiuqiang Huang, Stephen E StrelkovAbstract:In this study, clubroot resistance in the resynthesized European winter Brassica napus cv. ‘Tosca’ was introgressed into a Canadian spring canola line ‘11SR0099’, which was then crossed with the clubroot susceptible spring line ‘12DH0001’ to produce F1 seeds. The F1 plants were used to develop a doubled haploid (DH) mapping population. The parents and the DH lines were screened against ‘old’ Pathotypes 2F, 3H, 5I, 6M and 8N of the clubroot pathogen, Plasmodiophora brassicae, as well as against the ‘new’ Pathotypes 5X, 5L, 2B, 3A, 3D, 5G, 8E, 5C, 8J, 5K, 3O and 8P. Genotyping was conducted using a Brassica 15K SNP array. The clubroot screening showed that ‘Tosca, ‘11SR0099’ and the resistant DH lines were resistant to three (2F, 3H and 5I) of the five ‘old’ Pathotypes and four (2B, 3O, 8E and 8P) of the 12 ‘new’ Pathotypes, while being moderately resistant to the ‘old’ pathotype 8N and the ‘new’ Pathotypes 3D and 5G. ‘Tosca’ was susceptible to isolates representing pathotype 3A (the most common among the ‘new’ Pathotypes) as well as Pathotypes 6M, 5X, 5L, 5K and 8J. Linkage analysis and QTL mapping identified a ca. 0.88–0.95 Mb genomic region on the A03 chromosome of ‘Tosca’ as conferring resistance to Pathotypes 2F, 3H, 5I, 2B, 3D, 5G, 8E, 3O and 8P. The identified QTL genomic region housed the CRk, Crr3 and CRd gene(s). However, the susceptibility of ‘Tosca’ to most of the common virulent Pathotypes makes it unattractive as a sole CR donor in the breeding of commercial canola varieties in western Canada.
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Clubroot resistance derived from the European Brassica napus cv. ‘Tosca’ is not effective against virulent Plasmodiophora brassicae isolates from Alberta, Canada
'Springer Science and Business Media LLC', 2021Co-Authors: Rudolph Fredua-agyeman, Sheaufang Hwang, Hui Zhang, Igor Falak, Xiuqiang Huang, Stephen E StrelkovAbstract:Abstract In this study, clubroot resistance in the resynthesized European winter Brassica napus cv. ‘Tosca’ was introgressed into a Canadian spring canola line ‘11SR0099’, which was then crossed with the clubroot susceptible spring line ‘12DH0001’ to produce F1 seeds. The F1 plants were used to develop a doubled haploid (DH) mapping population. The parents and the DH lines were screened against ‘old’ Pathotypes 2F, 3H, 5I, 6M and 8N of the clubroot pathogen, Plasmodiophora brassicae, as well as against the ‘new’ Pathotypes 5X, 5L, 2B, 3A, 3D, 5G, 8E, 5C, 8J, 5K, 3O and 8P. Genotyping was conducted using a Brassica 15K SNP array. The clubroot screening showed that ‘Tosca, ‘11SR0099’ and the resistant DH lines were resistant to three (2F, 3H and 5I) of the five ‘old’ Pathotypes and four (2B, 3O, 8E and 8P) of the 12 ‘new’ Pathotypes, while being moderately resistant to the ‘old’ pathotype 8N and the ‘new’ Pathotypes 3D and 5G. ‘Tosca’ was susceptible to isolates representing pathotype 3A (the most common among the ‘new’ Pathotypes) as well as Pathotypes 6M, 5X, 5L, 5K and 8J. Linkage analysis and QTL mapping identified a ca. 0.88–0.95 Mb genomic region on the A03 chromosome of ‘Tosca’ as conferring resistance to Pathotypes 2F, 3H, 5I, 2B, 3D, 5G, 8E, 3O and 8P. The identified QTL genomic region housed the CRk, Crr3 and CRd gene(s). However, the susceptibility of ‘Tosca’ to most of the common virulent Pathotypes makes it unattractive as a sole CR donor in the breeding of commercial canola varieties in western Canada
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resistance to plasmodiophora brassicae in brassica rapa and brassica juncea genotypes from china
Plant Disease, 2015Co-Authors: Hui Zhang, Stephen E Strelkov, Jie Feng, Shujiang Zhang, Shifan Zhang, Rifei Sun, Sheaufang HwangAbstract:Clubroot disease, caused by Plasmodiophora brassicae Woronin, has become a major problem in cruciferous crops worldwide. Chinese cabbage (Brassica rapa), pak choi (B. rapa), and mustard (B. juncea) are important vegetable crops in China. Development of clubroot-resistant cultivars of these crops is urgently needed. In this study, 71 B. rapa and B. juncea genotypes from China, including cultivars and inbred lines, were evaluated for resistance to three P. brassicae Pathotypes. A significant interaction was observed between the P. brassicae Pathotypes and the Brassica genotypes. Pathotype 3, as defined on the differentials of Williams, exhibited the weakest virulence on all plant material. By contrast, Pathotypes 5 and 6 were both highly pathogenic on most of the tested genotypes. In all, 10 of the 14 Chinese cabbage cultivars were resistant to all three Pathotypes, while 4 were resistant only to a specific pathotype. Seven of eight progenies obtained from the selfing of Chinese cabbage cultivars were resistant to pathotype 3 but most were susceptible to Pathotypes 5 and 6. Most inbred lines of Chinese cabbage and all inbred lines of pak choi and mustard were susceptible to all three Pathotypes but their susceptibility was lower to pathotype 3 than to Pathotypes 5 and 6.
J A Walsh - One of the best experts on this subject based on the ideXlab platform.
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Genetic mapping of the novel Turnip mosaic virus resistance gene TuRB03 in Brassica napus
Theoretical and Applied Genetics, 2003Co-Authors: S. L. Hughes, P. J. Hunter, A. G. Sharpe, M. J. Kearsey, D. J. Lydiate, J A WalshAbstract:A new source of resistance to the pathotype 4 isolate of Turnip mosaic virus (TuMV) CDN 1 has been identified in Brassica napus (oilseed rape). Analysis of segregation of resistance to TuMV isolate CDN 1 in a backcross generation following a cross between a resistant and a susceptible B. napus line showed that the resistance was dominant and monogenic. Molecular markers linked to this dominant resistance were identified using amplified fragment length polymorphism (AFLP) and microsatellite bulk segregant analysis. Bulks consisted of individuals from a BC_1 population with the resistant or the susceptible phenotype following challenge with CDN 1. One AFLP and six microsatellite markers were associated with the resistance locus, named TuRB03 , and these mapped to the same region on chromosome N6 as a previously mapped TuMV resistance gene TuRB01 . Further testing of TuRB03 with other TuMV isolates showed that it was not effective against all pathotype 4 isolates. It was effective against some, but not all pathotype 3 isolates tested. It provided further resolution of TuMV Pathotypes by sub-dividing Pathotypes 3 and 4. TuRB03 also provides a new source of resistance for combining with other resistances in our attempts to generate durable resistance to this virus.
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pathotypic variation in turnip mosaic virus with special reference to european isolates
Plant Pathology, 1996Co-Authors: Carol E Jenner, J A WalshAbstract:A collection of 124 isolates of turnip mosaic virus was gathered from around the world, principally from European countries, and characterized by inoculation to four differential lines of Brassica napus (oilseed rape and swede). Three symptom phenotypes were induced-apparent immunity, local infection only, or systemic infection. Twelve distinct patterns, i.e. Pathotypes, were observed. Three Pathotypes were predominant in the collection: pathotype 1 isolates, which were the most common, did not overcome any of the most extreme sources of resistance in the differential lines. Of the other two, pathotype 3 isolates overcame one of the major sources of resistance and pathotype 4 isolates overcame all sources of resistance. The distribution of Pathotypes within Europe was examined. No pathotype was confined to any geographical area, although pathotype 4 isolates were not found in southern Europe or Asia. Most isolates (90) originated from Brassica hosts, while others were from other cruciferae genera (19) or non-crucifers (5). The species of plant that the isolates originated from was not clearly related to the pathotype of the isolates. Resistance to pathotype 1 isolates is controlled by a dominant allele in one of the differential lines, and resistance sources are being examined in the other lines. Isolates belonging to pathotype 1 appeared to be able to mutate readily to overcome the resistance in one of the rape differential lines, but no isolates appeared to mutate to overcome the other major source of resistance in the differentials. The implications of the results for disease control strategies are discussed.
Olivier Pruvost - One of the best experts on this subject based on the ideXlab platform.
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amplified fragment length polymorphism and multilocus sequence analysis based genotypic relatedness among pathogenic variants of xanthomonas citri pv citri and xanthomonas campestris pv bilvae
International Journal of Systematic and Evolutionary Microbiology, 2010Co-Authors: Lan Bui Thi Ngoc, Christian Verniere, Emmanuel Jouen, Nathalie Ahyou, Pierre Lefeuvre, Frederic Chiroleu, Lionel Gagnevin, Olivier PruvostAbstract:Three pathogenic variants (i.e. Pathotypes) have been described within Xanthomonas citri pv. citri, the causal agent of Asiatic citrus canker. Pathotype A strains naturally infect a wide range of Citrus species and members of some related genera. In contrast, Pathotypes A* and Aw have narrow host ranges within the genus Citrus and have been isolated from Mexican lime (Citrus aurantifolia L.) and from Mexican lime and alemow (Citrus macrophylla L.), respectively. We used amplified fragment length polymorphism (AFLP) and multilocus sequence analysis (MLSA) based on four partial housekeeping gene sequences (atpD, dnaK, efp and gyrB) for the genotypic classification of Xanthomonas citri pv. citri and the poorly characterized citrus pathogen Xanthomonas campestris pv. bilvae. A Mantel test showed that genetic distances derived from AFLP and MLSA were highly correlated. X. campestris pv. bilvae showed a close relatedness to the type strain of X. citri, indicating that this pathovar should be reclassified as X. citri pv. bilvae. All pathotype A* and Aw strains were most closely related to X. citri pv. citri strains with a wide host range (pathotype A), confirming previous DNA–DNA hybridization data. Pathotype Aw should be considered a junior synonym of pathotype A* on the basis of pathogenicity tests, AFLP, MLSA and PCR using pathovar-specific primers. Evolutionary genome divergences computed from AFLP data suggested that pathotype A* (including Aw strains) is a group of strains that shows a wider genetic diversity than pathotype A.
