Race diversity and virulence complexity ofPhytophthora infestans in Nepal

Ghimire, Sita R.; Hyde, Kevin D.; Hodgkiss, I. J.; Liew, E. C. Y.

doi:10.1007/bf02357903

Cited by 3 publications

(4 citation statements)

References 25 publications

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“…However, lower frequencies were observed in other studies, e.g. Nepal 30 out of 251, Estonia 86/432, Finland 66/269, Norway 38/105, Nordic countries (Denmark, Finland, Norway and Sweden) 31/177 and China 61/125 races (Hermansen et al ., ; Ghimire et al ., ; Lehtinen et al ., ; Li et al ., ; Runno‐Paurson et al ., ). It should be noted that in Denmark, Estonia, Finland, Norway and Sweden sexual populations are dominant, and the populations seems to be clonal in China and Nepal (although both mating types can be found), whereas the population in Ecuador is clonal.…”

Section: Discussionmentioning

confidence: 99%

Large subclonal variation in Phytophthora infestans populations associated with Ecuadorian potato landraces

Delgado

Monteros

et al. 2013

Plant Pathology

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The population of Phytophthora infestans on potato landraces in three provinces (Carchi, Chimborazo and Loja) of Ecuador was analysed. All isolates (n = 66) were of the A1 mating type. Simple sequence repeats (SSR) were used to assess the genetic diversity of the isolates. The P. infestans isolates from the potato landraces grouped in a single clade together with reference isolates belonging to the clonal lineage EC-1. In the 66 SSR profiles obtained, 31 multilocus genotypes were identified. The 66 isolates constituted 49 different races according to the Solanum demissum differential set (R1 to R11). The P. infestans population was complex and virulent on 4 to 11 R genes. Analysis showed that the subclonal variation in the Ecuadorian EC-1 clone is increasing over time and is much larger than clonal variation in lineages in the Netherlands and Nicaragua, suggesting high mutation rates and little or no selection in Ecuador.

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Section: Discussionmentioning

confidence: 99%

Large subclonal variation in Phytophthora infestans populations associated with Ecuadorian potato landraces

Delgado

Monteros

et al. 2013

Plant Pathology

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“…New populations belonging to the A2 mating types were claimed to be more pathogenic and hence fitter than old ones (Gisi & Cohen, 1996). The virulence testing of Nepalese P. infestans isolates revealed the presence of higher numbers of virulence factors in A2 isolates compared with A1 isolates (Ghimire et al, 2001). A high proportion of A2 at Hemja and a monotypic A2 population at Terathum could be the result of a more virulent and fitter A2 than the native A1.…”

Section: Discussionmentioning

confidence: 97%

“…The population from the hills was the most diverse followed by terai (a part of the Indo-Gangetic plains) and the high hill populations. Gleason and Shannon diversity indices indicated a moderate level of diversity in the overall Nepalese P. infestans population, and the virulence complexities were minimal (Ghimire et al, 2001). However, it was not possible to make any inference regarding changes in pathogen population based on the race composition study.…”

Section: Introductionmentioning

confidence: 98%

“…Such a change in epidemiological pattern and reduction in fungicide efficiency could be indicative of changes in the P. infestans populations. Ghimire et al (2001) characterized 251 isolates for race composition among the isolates used in this study and revealed the presence of 30 different races with variable virulence factors ranging from none to seven per isolate. The population from the hills was the most diverse followed by terai (a part of the Indo-Gangetic plains) and the high hill populations.…”

Section: Introductionmentioning

confidence: 99%

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Phenotypes ofPhytophthora infestans in Nepal: mating types and metalaxyl sensitivity

et al. 2001

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SummaryPotato late blight has appeared in epidemic proportions in Nepal since the mid 1990s and fungicides have been reported to be decreasingly effective in managing the disease.Phytophthora infestans isolates were collected from potato crops during 1999-2000 and analysis of 371 isolates for mating types and 270 isolates for metalaxyl sensitivity revealed the presence of both new and old populations. This is the first report on the presence of metalaxyl-resistant isolates in Nepal. The frequencies of A1 and A2 were 83 and 17%, respectively. Metalaxylresistant, intermediate and sensitive isolates were recorded as 10%, 12% and 78% respectively. Metalaxyl resistance was distributed in both mating types. Sites with a history of meta'laxyl use had a significantly higher number of resistant and intermediate isolates (~-~=20, P<0.01) than sites where metalaxyl had not been used. This study confirms the changes in population structure of P. infestans in Nepal.

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Variations in the Phytophthora infestans Population in Nepal as Revealed by Nuclear and Mitochondrial DNA Polymorphisms

Ghimire¹,

Hyde²,

Hodgkiss³

et al. 2003

Phytopathology®

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Phytophthora infestans isolates collected from potato and tomato crops from various parts of Nepal during the 1999 and 2000 crop seasons were characterized for nuclear and mitochondrial DNA polymorphisms using restriction fragment length polymorphism markers. The nuclear DNA probe RG57 detected 11 multilocus genotypes among 280 isolates. Three genotypes were detected 21 times or more, constituting 94% of the total population, whereas frequencies of other genotypes ranged from 0.004 to 0.014. The overall genotypic diversity as estimated by the Gleason index was 1.78. Most of the overall diversity was present at the highest level (i.e., interregional, 46%), indicating limited gene flow among regions. Cluster analysis of multilocus genotypes derived from RG57 and mating type data for Nepalese isolates and representative isolates worldwide showed Nepalese isolates grouping into four clusters. Characterization of 67 isolates for mitochondrial DNA polymorphisms revealed the presence of two mt-haplotypes, Ia and Ib with the proportions of 0.88 and 0.12, respectively. Polymorphisms in nuclear and mitochondrial DNA revealed a moderate level of diversity in this population. Genotype NP3 had an identical RG57 fingerprint to US1 and had mt-haplotype Ib, confirming the presence of an old population in Nepal. Most of the genotypes had a different RG57 fingerprint than that of US1 and mt-haplotype Ia, the common characteristics of new populations. The presence of a new population at high proportions in Nepal was consistent with the global trend of mt-haplotype distribution, and suggests the displacement of old populations. This study indicates at least three possible introductions of P. infestans to Nepal.

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Race diversity and virulence complexity ofPhytophthora infestans in Nepal

Cited by 3 publications

References 25 publications

Large subclonal variation in Phytophthora infestans populations associated with Ecuadorian potato landraces

Large subclonal variation in Phytophthora infestans populations associated with Ecuadorian potato landraces

Phenotypes ofPhytophthora infestans in Nepal: mating types and metalaxyl sensitivity

Variations in the Phytophthora infestans Population in Nepal as Revealed by Nuclear and Mitochondrial DNA Polymorphisms

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