-
[show abstract]
[hide abstract]
ABSTRACT: Powdery mildew (PMD) of soybean [Glycine max (L.) Merr.] is caused by the fungus Microsphaera diffusa. Severe infection of PMD on susceptible varieties often causes premature defoliation and chlorosis of the leaves, which can result in considerable yield losses under favorable environmental conditions for disease development in the field. A total of 334 F(7)-derived recombinant inbred lines (RILs) from a cross of a PMD susceptible soybean cultivar Wyandot and PMD-resistant PI 567301B were used for genetic mapping of PMD resistance in PI 567301B and for development of molecular markers tightly linked to the gene. The result of the PMD screening for each line in the field was in agreement with that in the greenhouse test. The genetic map containing the PMD resistance gene was constructed in a 3.3 cM interval flanked by two simple sequence repeat (SSR) markers on chromosome 16. The PMD resistance gene was mapped at the same location with SSR marker BARCSOYSSR_16_1291, indicating that there was no recombination between the 334 RILs and this marker. In addition, a single nucleotide polymorphism (SNP) marker developed by high-resolution melting curve analysis and a cleaved amplified polymorphic sequence (CAPS) marker with Rsa1 recognition site were used for the genetic mapping. These two markers were also mapped to the same genomic location with the PMD resistance gene. We validated three tightly linked markers to the PMD resistance gene using 38 BC(6)F(2) lines and corresponding BC(6)F(2:3) families. The three marker genotypes of the backcross lines predicted the observed PMD phenotypes of the lines with complete accuracy. We have mapped a putatively novel single dominant PMD resistance gene in PI 567301B and developed three new molecular markers closely linked to the gene. Molecular markers developed from this study may be used for high-throughput marker-assisted breeding for PMD resistance with the gene from PI 567301B.
Theoretical and Applied Genetics 06/2012; 125(6):1159-68. · 3.30 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Powdery mildew (caused by Microsphaera diffusa Cooke & Peck) is a common disease of soybean in many soybean-growing regions of the world and under greenhouse conditions. The previously reported Rmd locus of soybean for resistance to powdery mildew was mapped on soybean molecular linkage group J (chromosome 16). We have discovered a single dominant gene in PI 243540 that provides season-long resistance to powdery mildew. The objective of this study was to map the powdery mildew resistance gene in PI 243540 with PCR-based molecular markers. One hundred eighty-four F2 plants and their F(2:3) families from a cross between the powdery mildew susceptible cultivar 'Wyandot' and PI 243540 were screened with M. diffusa in greenhouses. Bulked segregant analysis (BSA) with SSR markers was used to identify the tentative genomic location of the gene. The BSA localized the gene to a genomic region in soybean chromosome 16. A linkage map with seven SSR and six SNP markers flanking the gene was constructed. We positioned the gene between SSR marker Sat_224 and SNP marker BARC-021875-04228 at distances of 9.6 and 1.3 cM from the markers, respectively. The map position of the gene was slightly different from previously reported map positions of the only known Rmd locus. We have mapped a single dominant gene, tentatively called Rmd_PI243540, near the previously known Rmd locus on chromosome 16. The molecular markers flanking the gene will be useful for marker-assisted selection of this gene.
Genome 05/2010; 53(5):400-5. · 1.65 Impact Factor
-
[show abstract]
[hide abstract]
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
-
[show abstract]
[hide abstract]
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
-
[show abstract]
[hide abstract]
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
-
[show abstract]
[hide abstract]
ABSTRACT: The soybean aphid (Aphis glycines Matsumura) is a pest of soybean [Glycine max (L.) Merr.] in many soybean growing countries of the world. Host plant resistance is a very useful component of an integrated pest management program to control an insect problem. A maturity group (MG) IV plant introduction (PI) 243540 showed strong antibiosis resistance against the Ohio biotype of the soybean aphid. The objective of this study was to determine the inheritance of soybean aphid resistance gene(s) in PI 243540. The F1, F2, and F2-derived F3 families from a cross between an aphid susceptible cultivar Wyandot and resistant PI 243540 were screened in a greenhouse with the Ohio biotype of the soybean aphid. All F1 plants were resistant to the soybean aphid and 2 analysis of segregation of 341 F2 plants indicated a fit to a single dominant gene ratio of 3:1 (P = 0.51). Segregation in 330 F2:3 families fit an expected 1:2:1 ratio (P = 0.40). Our results indicate that a single dominant gene controls the soybean aphid resistance in PI 243540. The simple inheritance of this gene should be helpful to quickly transfer the gene to susceptible elite cultivars using the backcross breeding approach.
-
[show abstract]
[hide abstract]
ABSTRACT: Bean pod mottle virus (BPMV) is a threat to soybean in most soybean [Glycine max (L.) Merr.] growing states of the USA. In the absence of complete resistance of soybean to BPMV, partial resistance can play an important role in reducing seed-yield and seed-quality losses from this virus. The objectives of this study were: (i) to evaluate plant introductions (PIs) for expression of leaf symptoms under greenhouse conditions following inoculation with BPMV, and (ii) to determine the genetic diversity among soybean genotypes with differences in leaf symptoms of BPMV. Large significant (P <= 0.001) differences in expression of BPMV leaf symptoms among genotypes in the greenhouse were detected. A genetic diversity study was conducted on 48 soybean genotypes differing in leaf symptoms of BPMV using 271 alleles amplified by 84 microsatellite primer pairs. The average polymorphism information content for the microsatellites was 0.53 and the average number of alleles per microsatellite was 3.23. The soybean genotypes clustered into distinct groups based on their country of origin and/or their BPMV leaf symptoms. Based on the microsatellite data, the genotypes were clustered into seven groups. Groups 1, 2 and 4 included genotypes from China only, group 3 included genotypes from the USA only and group 7 included genotypes from Japan only. Group 1 consisted of genotypes with low leaf symptoms of BPMV while group 6 was formed of genotypes with high leaf symptoms of BPMV.
