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Mace ES, Xia L, Jordan DR, Halloran K, Parh DK, Huttner E, Wenzl P, Kilian A. DArT markers: diversity analyses and mapping in Sorghum bicolor. BMC Genomics 2008. [PMID: 18208620 DOI: 10.1186/1471‐2164‐9‐26] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The sequential nature of gel-based marker systems entails low throughput and high costs per assay. Commonly used marker systems such as SSR and SNP are also dependent on sequence information. These limitations result in high cost per data point and significantly limit the capacity of breeding programs to obtain sufficient return on investment to justify the routine use of marker-assisted breeding for many traits and particularly quantitative traits. Diversity Arrays Technology (DArT) is a cost effective hybridisation-based marker technology that offers a high multiplexing level while being independent of sequence information. This technology offers sorghum breeding programs an alternative approach to whole-genome profiling. We report on the development, application, mapping and utility of DArT markers for sorghum germplasm. RESULTS A genotyping array was developed representing approximately 12,000 genomic clones using PstI+BanII complexity with a subset of clones obtained through the suppression subtractive hybridisation (SSH) method. The genotyping array was used to analyse a diverse set of sorghum genotypes and screening a Recombinant Inbred Lines (RIL) mapping population. Over 500 markers detected variation among 90 accessions used in a diversity analysis. Cluster analysis discriminated well between all 90 genotypes. To confirm that the sorghum DArT markers behave in a Mendelian manner, we constructed a genetic linkage map for a cross between R931945-2-2 and IS 8525 integrating DArT and other marker types. In total, 596 markers could be placed on the integrated linkage map, which spanned 1431.6 cM. The genetic linkage map had an average marker density of 1/2.39 cM, with an average DArT marker density of 1/3.9 cM. CONCLUSION We have successfully developed DArT markers for Sorghum bicolor and have demonstrated that DArT provides high quality markers that can be used for diversity analyses and to construct medium-density genetic linkage maps. The high number of DArT markers generated in a single assay not only provides a precise estimate of genetic relationships among genotypes, but also their even distribution over the genome offers real advantages for a range of molecular breeding and genomics applications.
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Affiliation(s)
- Emma S Mace
- The Department of Primary Industries & Fisheries, Queensland, Hermitage Research Station, Warwick, QLD 4370, Australia.
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Knoll J, Gunaratna N, Ejeta G. QTL analysis of early-season cold tolerance in sorghum. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2007. [PMID: 18097644 DOI: 10.1007/s00122‐007‐0692‐0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
Abstract
Cool temperatures during the early-growing season are a major limitation to growing sorghum [Sorghum bicolor (L.) Moench] in temperate areas. Several landraces from China have been found to exhibit higher emergence and greater seedling vigor under cool conditions than most breeding lines currently available, but tend to lack desirable agronomic characteristics. The introgression of desirable genes from Chinese landraces into elite lines could be expedited by marker-assisted selection. Using a population of 153 RI lines, developed from a cross between Chinese landrace 'Shan Qui Red,' (SQR, cold-tolerant) and SRN39 (cold-sensitive), QTL associated with early-season performance under both cold and optimal conditions were identified by single marker analysis, simple interval mapping (SIM), and composite interval mapping (CIM). Germination was observed under controlled conditions, and other traits were measured in field plantings. Two QTL for germination were identified: one on linkage group SBI-03a, derived from SRN39, was significant under cold and optimal temperatures. The other, on group SBI-07b, showed greater significance under cold temperatures and was contributed by SQR. A region of group SBI-01a, derived from SQR, showed strong associations with seedling emergence and seedling vigor scores under early and late field plantings. A QTL for both early and late emergence was identified by CIM on SBI-02 which favored the SRN39 allele. SIM identified a QTL for early vigor on SBI-04 favoring the SQR genotype. Further studies are needed to validate the effects of these QTL, but they represent the first step in development of a marker-assisted breeding effort to improve early-season performance in sorghum.
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Affiliation(s)
- Joseph Knoll
- Department of Agronomy, Purdue University, West Lafayette, IN, 47907, USA
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53
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Wu YQ, Huang Y. An SSR genetic map of Sorghum bicolor (L.) Moench and its comparison to a published genetic map. Genome 2007; 50:84-9. [PMID: 17546074 DOI: 10.1139/g06-133] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sorghum bicolor (L.) Moench is an important grain and forage crop grown worldwide. We developed a simple sequence repeat (SSR) linkage map for sorghum using 352 publicly available SSR primer pairs and a population of 277 F2 individuals derived from a cross between the Westland A line and PI 550610. A total of 132 SSR loci appeared polymorphic in the mapping population, and 118 SSRs were mapped to 16 linkage groups. These mapped SSR loci were distributed throughout 10 chromosomes of sorghum, and spanned a distance of 997.5 cM. More important, 38 new SSR loci were added to the sorghum genetic map in this study. The mapping result also showed that chromosomes SBI-01, SBI-02, SBI-05, and SBI-06 each had 1 linkage group; the other 6 chromosomes were composed of 2 linkage groups each. Except for 5 closely linked marker flips and 1 locus (Sb6_34), the marker order of this map was collinear to a published sorghum map, and the genetic distances of common marker intervals were similar, with a difference ratio <or= 0.05 between the 2 maps. The difference ratio is a new index developed in this study that can be used to compare the genetic distances of DNA markers between 2 maps. This SSR map carrying additional SSR markers will facilitate mapping quantitative trait loci to the sorghum genome and map-based gene cloning. Furthermore, the novel method for calculating distance between DNA markers will be a useful tool for the comparative analysis of genetic markers between linkage maps with different genetic backgrounds and the alignment of different sorghum genetic maps.
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Affiliation(s)
- Y Q Wu
- USDA-ARS Plant Science Research Laboratory, 1301 N. Western Rd, Stillwater, OK 74075, USA
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Nagy ED, Lee TC, Ramakrishna W, Xu Z, Klein PE, SanMiguel P, Cheng CP, Li J, Devos KM, Schertz K, Dunkle L, Bennetzen JL. Fine mapping of the Pc locus of Sorghum bicolor, a gene controlling the reaction to a fungal pathogen and its host-selective toxin. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2007; 114:961-70. [PMID: 17356869 DOI: 10.1007/s00122-006-0481-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Accepted: 11/30/2006] [Indexed: 05/14/2023]
Abstract
Milo disease in sorghum is caused by isolates of the soil-borne fungus Periconia circinata that produce PC-toxin. Susceptibility to milo disease is conditioned by a single, semi-dominant gene, termed Pc. The susceptible allele (Pc) converts to a resistant form (pc) spontaneously at a gametic frequency of 10(-3) to 10(-4). A high-density genetic map was constructed around the Pc locus using DNA markers, allowing the Pc gene to be delimited to a 0.9 cM region on the short arm of sorghum chromosome 9. Physically, the Pc-region was covered by a single BAC clone. Sequence analysis of this BAC revealed twelve gene candidates. Several of the predicted genes in the region are homologous to disease resistance loci, including one NBS-LRR resistance gene analogue that is present in multiple tandem copies. Analysis of pc isolines derived from Pc/Pc sorghum suggests that one or more members of this NBS-LRR gene family are the Pc genes that condition susceptibility.
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MESH Headings
- Alleles
- Amino Acid Sequence
- Ascomycota/pathogenicity
- Chromosomes, Artificial, Bacterial
- Chromosomes, Plant
- Cloning, Molecular
- Crosses, Genetic
- DNA, Plant
- Gene Dosage
- Gene Duplication
- Genes, Dominant
- Genes, Plant
- Genetic Markers
- Genotype
- Molecular Sequence Data
- Physical Chromosome Mapping
- Polymorphism, Single-Stranded Conformational
- Recombination, Genetic
- Sequence Homology, Amino Acid
- Sorghum/genetics
- Toxins, Biological/genetics
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Affiliation(s)
- Ervin D Nagy
- Department of Genetics, University of Georgia, Athens, GA, 30602, USA
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55
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Jiang J, Gill BS. Current status and the future of fluorescence in situ hybridization (FISH) in plant genome research. Genome 2006; 49:1057-68. [PMID: 17110986 DOI: 10.1139/g06-076] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fluorescence in situ hybridization (FISH), which allows direct mapping of DNA sequences on chromosomes, has become the most important technique in plant molecular cytogenetics research. Repetitive DNA sequence can generate unique FISH patterns on individual chromosomes for karyotyping and phylogenetic analysis. FISH on meiotic pachytene chromosomes coupled with digital imaging systems has become an efficient method to develop physical maps in plant species. FISH on extended DNA fibers provides a high-resolution mapping approach to analyze large DNA molecules and to characterize large genomic loci. FISH-based physical mapping provides a valuable complementary approach in genome sequencing and map-based cloning research. We expect that FISH will continue to play an important role in relating DNA sequence information to chromosome biology. FISH coupled with immunoassays will be increasingly used to study features of chromatin at the cytological level that control expression and regulation of genes.
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Affiliation(s)
- Jiming Jiang
- Department of Horticulture, University of Wisconsin, Madison, WI 53706, USA.
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Kim JS, Islam-Faridi MN, Klein PE, Stelly DM, Price HJ, Klein RR, Mullet JE. Comprehensive molecular cytogenetic analysis of sorghum genome architecture: distribution of euchromatin, heterochromatin, genes and recombination in comparison to rice. Genetics 2005; 171:1963-76. [PMID: 16143604 PMCID: PMC1456119 DOI: 10.1534/genetics.105.048215] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Accepted: 08/21/2005] [Indexed: 11/18/2022] Open
Abstract
Cytogenetic maps of sorghum chromosomes 3-7, 9, and 10 were constructed on the basis of the fluorescence in situ hybridization (FISH) of approximately 18-30 BAC probes mapped across each of these chromosomes. Distal regions of euchromatin and pericentromeric regions of heterochromatin were delimited for all 10 sorghum chromosomes and their DNA content quantified. Euchromatic DNA spans approximately 50% of the sorghum genome, ranging from approximately 60% of chromosome 1 (SBI-01) to approximately 33% of chromosome 7 (SBI-07). This portion of the sorghum genome is predicted to encode approximately 70% of the sorghum genes ( approximately 1 gene model/12.3 kbp), assuming that rice and sorghum encode a similar number of genes. Heterochromatin spans approximately 411 Mbp of the sorghum genome, a region characterized by a approximately 34-fold lower rate of recombination and approximately 3-fold lower gene density compared to euchromatic DNA. The sorghum and rice genomes exhibit a high degree of macrocolinearity; however, the sorghum genome is approximately 2-fold larger than the rice genome. The distal euchromatic regions of sorghum chromosomes 3-7 and 10 are approximately 1.8-fold larger overall and exhibit an approximately 1.5-fold lower average rate of recombination than the colinear regions of the homeologous rice chromosomes. By contrast, the pericentromeric heterochromatic regions of these chromosomes are on average approximately 3.6-fold larger in sorghum and recombination is suppressed approximately 15-fold compared to the colinear regions of rice chromosomes.
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Affiliation(s)
- J-S Kim
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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Klein RR, Klein PE, Mullet JE, Minx P, Rooney WL, Schertz KF. Fertility restorer locus Rf1 [corrected] of sorghum (Sorghum bicolor L.) encodes a pentatricopeptide repeat protein not present in the colinear region of rice chromosome 12. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2005. [PMID: 16078015 DOI: 10.1007/s00122-005-2011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
With an aim to clone the sorghum fertility restorer gene Rf1, a high-resolution genetic and physical map of the locus was constructed. The Rf1 locus was resolved to a 32-kb region spanning four open reading frames: a plasma membrane Ca(2+)-ATPase, a cyclin D-1, an unknown protein, and a pentatricopeptide repeat (PPR13) gene family member. An approximately 19-kb region spanning the cyclin D-1 and unknown protein genes was completely conserved between sterile and fertile plants as was the sequence spanning the coding region of the Ca(2+)-ATPase. In contrast, 19 sequence polymorphisms were located in an approximately 7-kb region spanning PPR13, and all markers cosegregated with the fertility restoration phenotype. PPR13 was predicted to encode a mitochondrial-targeted protein containing a single exon with 14 PPR repeats, and the protein is classified as an E-type PPR subfamily member. To permit sequence-based comparison of the sorghum and rice genomes in the Rf1 region, 0.53 Mb of sorghum chromosome 8 was sequenced and compared to the colinear region of rice chromosome 12. Genome comparison revealed a mosaic pattern of colinearity with an approximately 275-kb gene-poor region with little gene conservation and an adjacent, approximately 245-kb gene-rice region that is more highly conserved between rice and sorghum. Despite being located in a region of high gene conservation, sorghum PPR13 was not located in a colinear position on rice chromosome 12. The present results suggest that sorghum PPR13 represents a potential candidate for the sorghum Rf1 gene, and its presence in the sorghum genome indicates a single gene transposition event subsequent to the divergence of rice and sorghum ancestors.
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Affiliation(s)
- R R Klein
- Southern Plains Agricultural Research Center, USDA-ARS, College Station, TX 77845, USA.
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58
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Klein RR, Klein PE, Mullet JE, Minx P, Rooney WL, Schertz KF. Fertility restorer locus Rf1 [corrected] of sorghum (Sorghum bicolor L.) encodes a pentatricopeptide repeat protein not present in the colinear region of rice chromosome 12. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2005; 111:994-1012. [PMID: 16078015 DOI: 10.1007/s00122-005-2011-y] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Accepted: 03/17/2005] [Indexed: 05/03/2023]
Abstract
With an aim to clone the sorghum fertility restorer gene Rf1, a high-resolution genetic and physical map of the locus was constructed. The Rf1 locus was resolved to a 32-kb region spanning four open reading frames: a plasma membrane Ca(2+)-ATPase, a cyclin D-1, an unknown protein, and a pentatricopeptide repeat (PPR13) gene family member. An approximately 19-kb region spanning the cyclin D-1 and unknown protein genes was completely conserved between sterile and fertile plants as was the sequence spanning the coding region of the Ca(2+)-ATPase. In contrast, 19 sequence polymorphisms were located in an approximately 7-kb region spanning PPR13, and all markers cosegregated with the fertility restoration phenotype. PPR13 was predicted to encode a mitochondrial-targeted protein containing a single exon with 14 PPR repeats, and the protein is classified as an E-type PPR subfamily member. To permit sequence-based comparison of the sorghum and rice genomes in the Rf1 region, 0.53 Mb of sorghum chromosome 8 was sequenced and compared to the colinear region of rice chromosome 12. Genome comparison revealed a mosaic pattern of colinearity with an approximately 275-kb gene-poor region with little gene conservation and an adjacent, approximately 245-kb gene-rice region that is more highly conserved between rice and sorghum. Despite being located in a region of high gene conservation, sorghum PPR13 was not located in a colinear position on rice chromosome 12. The present results suggest that sorghum PPR13 represents a potential candidate for the sorghum Rf1 gene, and its presence in the sorghum genome indicates a single gene transposition event subsequent to the divergence of rice and sorghum ancestors.
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Affiliation(s)
- R R Klein
- Southern Plains Agricultural Research Center, USDA-ARS, College Station, TX 77845, USA.
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Bowers JE, Arias MA, Asher R, Avise JA, Ball RT, Brewer GA, Buss RW, Chen AH, Edwards TM, Estill JC, Exum HE, Goff VH, Herrick KL, Steele CLJ, Karunakaran S, Lafayette GK, Lemke C, Marler BS, Masters SL, McMillan JM, Nelson LK, Newsome GA, Nwakanma CC, Odeh RN, Phelps CA, Rarick EA, Rogers CJ, Ryan SP, Slaughter KA, Soderlund CA, Tang H, Wing RA, Paterson AH. Comparative physical mapping links conservation of microsynteny to chromosome structure and recombination in grasses. Proc Natl Acad Sci U S A 2005; 102:13206-11. [PMID: 16141333 PMCID: PMC1201573 DOI: 10.1073/pnas.0502365102] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nearly finished sequences for model organisms provide a foundation from which to explore genomic diversity among other taxonomic groups. We explore genome-wide microsynteny patterns between the rice sequence and two sorghum physical maps that integrate genetic markers, bacterial artificial chromosome (BAC) fingerprints, and BAC hybridization data. The sorghum maps largely tile a genomic component containing 41% of BACs but 80% of single-copy genes that shows conserved microsynteny with rice and partially tile a nonsyntenic component containing 46% of BACs but only 13% of single-copy genes. The remaining BACs are centromeric (4%) or unassigned (8%). The two genomic components correspond to cytologically discernible "euchromatin" and "heterochromatin." Gene and repetitive DNA distributions support this classification. Greater microcolinearity in recombinogenic (euchromatic) than nonrecombinogenic (heterochromatic) regions is consistent with the hypothesis that genomic rearrangements are usually deleterious, thus more likely to persist in nonrecombinogenic regions by virtue of Muller's ratchet. Interchromosomal centromeric rearrangements may have fostered diploidization of a polyploid cereal progenitor. Model plant sequences better guide studies of related genomes in recombinogenic than nonrecombinogenic regions. Bridging of 35 physical gaps in the rice sequence by sorghum BAC contigs illustrates reciprocal benefits of comparative approaches that extend at least across the cereals and perhaps beyond.
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Affiliation(s)
- John E Bowers
- Plant Genome Mapping Laboratory, University of Georgia, Athens, GA 30602, USA
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Toward sequencing the sorghum genome. A U.S. National Science Foundation-sponsored workshop report. PLANT PHYSIOLOGY 2005; 138:1898-902. [PMID: 16172096 PMCID: PMC1183381 DOI: 10.1104/pp.105.065136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Revised: 05/03/2005] [Accepted: 06/05/2005] [Indexed: 05/04/2023]
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Kim JS, Klein PE, Klein RR, Price HJ, Mullet JE, Stelly DM. Molecular cytogenetic maps of sorghum linkage groups 2 and 8. Genetics 2005; 169:955-65. [PMID: 15489513 PMCID: PMC1449123 DOI: 10.1534/genetics.104.026765] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2004] [Accepted: 10/26/2004] [Indexed: 11/18/2022] Open
Abstract
To integrate genetic, physical, and cytological perspectives of the Sorghum bicolor genome, we selected 40 landed bacterial artificial chromosome (BAC) clones that contain different linkage map markers, 21 from linkage group 2 (LG-02) and 19 from linkage group 8 (LG-08). Multi-BAC probe cocktails were constructed for each chromosome from the landed BACs, which were also preevaluated for FISH signal quality, relative position, and collective chromosome coverage. Comparison to the corresponding linkage map revealed full concordance of locus order between cytological and prior segregation analyses. The pericentromeric heterochromatin constituted a large quasi-uniform block in each bivalent and was especially large in the bivalent corresponding to LG-08. Centromere positions in LG-02 and LG-08 were progressively delimited using FISH to identify landed BACs for which the FISH signals visibly flanked the centromere. Alignment of linkage and cytological maps revealed that pericentromeric heterochromatin of these sorghum chromosomes is largely devoid of recombination, which is mostly relegated to the more distal regions, which are largely euchromatic. This suggests that the sorghum genome is thus even more amenable to physical mapping of genes and positional cloning than the C-value alone might suggest. As a prelude to positional cloning of the fertility restorer, Rf1, FISH of BAC clones flanking the Rf1 locus was used to delimit the chromosomal position of the gene. FISH of BACs that contain the most proximal linkage markers enabled localization of Rf1 to a approximately 0.4-Mbp euchromatic region of LG-08. Cytogenetic analyses of Rf1 and other trait loci will aid in assessing the feasibility of positional cloning and help formulate strategies required for cloning this and other agriculturally critical genes.
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Affiliation(s)
- Jeong-Soon Kim
- Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, Texas 77843-2474, USA
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