Publications (32) View all
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Article: Population genetic structure of Aphis glycines.
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ABSTRACT: The soybean aphid (Aphis glycines Matsumura) is an invasive pest of cultivated soybean (Glycine max L.) in North America. After the initial invasion in 2000, the aphid has quickly spread across most of the United States and Canada, suggesting large-scale dispersal and rapid adaptation to new environments. Using microsatellite markers from closely related species, we compared the genetic diversity and the amount of genetic differentiation within and among 2 South Korean and 10 North American populations. Overall allelic polymorphism was low, never exceeding four alleles per locus. However, differences in genetic diversity were seen among South Korean and North American populations in terms of heterozygote excesses and genotypic richness. Within North America, two populations (Michigan and Ontario), had lower genetic diversities and exhibited high genetic differentiation compared with the remaining eight populations. The earlier collection time of Michigan and Ontario samples explained the genetic differences better than geographic subdivisions. These data indicate a pattern of small colonizing populations on soybeans, followed by rapid clonal amplification and subsequent large-scale dispersal across North America.Environmental Entomology 09/2009; 38(4):1301-11. · 1.56 Impact Factor -
Article: Cross-species amplification and polymorphism of microsatellite loci in the soybean aphid, Aphis glycines.
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ABSTRACT: We tested the utility of 18 previously characterized Aphis spp. microsatellite loci for polymorphism and differentiation among populations of the soybean aphid, Aphis glycines. Loci were chosen from a closely related species (Aphis gossypii) and a more distantly related species (Aphis fabae). We found nine loci to be polymorphic among Korean and North American populations. Overall expected heterozygosity was moderate (average: 0.47; range: 0-1), although populations substantially differed in deviations from Hardy-Weinberg equilibrium. These loci will be valuable in characterizing population differentiation, migration and adaptation in an economically important pest of soybeans.Journal of Economic Entomology 07/2009; 102(3):1389-92. · 1.70 Impact Factor -
Article: Genetic linkage mapping of the soybean aphid resistance gene in PI 243540.
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ABSTRACT: The soybean aphid (Aphis glycines Matsumura) is a pest of soybean [Glycine max (L.) Merr.] in many soybean growing countries of the world, mainly in Asia and North America. A single dominant gene in PI 243540 confers resistance to the soybean aphid. The objectives of this study were to identify simple sequence repeat (SSR) markers closely linked to the gene in PI 243540 and to position the gene on the consensus soybean genetic map. One hundred eighty-four F2 plants and their F2:3 families from a cross between the susceptible cultivar Wyandot and PI 243540, and the two parental lines were screened with the Ohio biotype of soybean aphid using greenhouse choice tests. A SSR marker from each 10-cM section of the consensus soybean map was selected for bulked segregant analysis (BSA) to identify the tentative genomic location of the gene. The BSA technique was useful to localize the gene to a genomic region in soybean linkage group (LG) F. The entire F2 population was then screened with polymorphic SSR markers from this genomic region and a linkage map with nine SSR markers flanking the gene was constructed. The aphid resistance gene was positioned in the interval between SSR markers Satt334 and Sct_033 on LG F. These SSR markers will be useful for marker assisted selection of this gene. The aphid resistance gene from PI 243540 mapped to a different linkage group than the only named soybean aphid resistance gene, Rag1, from 'Dowling'. Also, the responses of the two known biotypes of the soybean aphid to the gene from PI 243540 and Rag1 were different. Thus, the aphid resistance gene from PI 243540 was determined to be a new and independent gene that has been named Rag2.Theoretical and Applied Genetics 08/2008; 117(6):955-62. · 3.30 Impact Factor -
Article: Analysis of tall fescue ESTs representing different abiotic stresses, tissue types and developmental stages
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ABSTRACT: Abstract Background Tall fescue ( Festuca arundinacea Schreb) is a major cool season forage and turf grass species grown in the temperate regions of the world. In this paper we report the generation of a tall fescue expressed sequence tag (EST) database developed from nine cDNA libraries representing tissues from different plant organs, developmental stages, and abiotic stress factors. The results of inter-library and library-specific in silico expression analyses of these ESTs are also reported. Results A total of 41,516 ESTs were generated from nine cDNA libraries of tall fescue representing tissues from different plant organs, developmental stages, and abiotic stress conditions. The Festuca Gene Index (FaGI) has been established. To date, this represents the first publicly available tall fescue EST database. In silico gene expression studies using these ESTs were performed to understand stress responses in tall fescue. A large number of ESTs of known stress response gene were identified from stressed tissue libraries. These ESTs represent gene homologues of heat-shock and oxidative stress proteins, and various transcription factor protein families. Highly expressed ESTs representing genes of unknown functions were also identified in the stressed tissue libraries. Conclusion FaGI provides a useful resource for genomics studies of tall fescue and other closely related forage and turf grass species. Comparative genomic analyses between tall fescue and other grass species, including ryegrasses ( Lolium sp.), meadow fescue ( F. pratensis ) and tetraploid fescue ( F. arundinacea var glaucescens ) will benefit from this database. These ESTs are an excellent resource for the development of simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) PCR-based molecular markers.BMC Plant Biology. 01/2008; -
Article: Genetic mapping of three quantitative trait loci for soybean aphid resistance in PI 567324.
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ABSTRACT: Host-plant resistance is an effective method for controlling soybean aphid (Aphis glycines Matsumura), the most damaging insect pest of soybean (Glycine max (L.) Merr.) in North America. Recently, resistant soybean lines have been discovered and at least four aphid resistance genes (Rag1, Rag2, Rag3 and rag4) have been mapped on different soybean chromosomes. However, the evolution of new soybean aphid biotypes capable of defeating host-plant resistance conferred by most single genes demonstrates the need for finding germplasm with multigenic resistance to the aphid. This study was conducted to map quantitative trait loci (QTL) for aphid resistance in PI 567324. We identified two major QTL (QTL_13_1 and QTL_13_2) for aphid resistance on soybean chromosome 13 using 184 recombinant inbred lines from a 'Wyandot' × PI 567324 cross. QTL_13_1 was located close to the previously reported Rag2 gene locus, and QTL_13_2 was close to the rag4 locus. A minor QTL (QTL_6_1) was also detected on chromosome 6, where no gene for soybean aphid resistance has been reported so far. These results indicate that PI 567324 possesses oligogenic resistance to the soybean aphid. The molecular markers closely linked to the QTL reported here will be useful for development of cultivars with oligogenic resistance that are expected to provide broader and more durable resistance against soybean aphids compared with cultivars with monogenic resistance.Heredity advance online publication, 13 March 2013; doi:10.1038/hdy.2013.10.Heredity 03/2013; · 4.60 Impact Factor
