-
[show abstract]
[hide abstract]
ABSTRACT: In soybean, the W4 gene encoding dihydroflavonol-4-reductase controls anthocyanin pigment biosynthesis in flowers. The mutant allele, w4-m, is characterized by variegated flowers and was evolved from the insertion of an endogenous transposable element, Tgm9, in intron II of the W4 gene. In the w4-m mutant line, reversion of the unstable allele from variegated to normal purple flower in revertants would indicate Tgm9's excision accompanied by its insertion into a second locus. We identified a male-sterile, female-sterile mutant from such germinal revertant bearing purple flowers. The objectives of our investigation were to map the sterility locus, identify candidate genes for the male-fertile, female-fertile phenotype, and then determine if sterility is associated with the insertion of Tgm9 in the sterility locus. We used bulked segregant analysis to map the locus to molecular linkage group J (chromosome 16). Fine mapping enabled us to flank the locus to a 62-kb region that contains only five predicted genes. One of the genes in that region, Glyma16g07850.1, codes for a helicase. A rice homolog of this gene has been shown to control crossing over and fertility phenotype. Thus, Glyma16g07850.1 is most likely the gene regulating the male and female fertility phenotype in soybean. DNA blot analysis of the segregating individuals for Tgm9 showed perfect association between sterility and the presence of the transposon. Most likely, the sterility mutation was caused by the insertion of Tgm9. The transposable element should facilitate identification of the male- and female-fertility gene. Characterization of the fertility gene will provide vital molecular insight on the reproductive biology of soybean and other plants.
Functional & Integrative Genomics 11/2012; · 3.83 Impact Factor
-
Gregory D May,
Gary Stacey,
Randy C Shoemaker,
Jianchang Du,
Uffe Hellsten,
Dong Xu,
Dan Rokhsar,
Brian Abernathy,
Montona Futrell-Griggs,
Jianlin Cheng, [......],
Jeremy Schmutz,
Madan K Bhattacharyya,
Trupti Joshi,
Taishi Umezawa,
Navdeep Gill,
Tetsuya Sakurai,
Liucun Zhu,
Yeisoo Yu,
Zhixi Tian,
Scott A Jackson
-
[show abstract]
[hide abstract]
ABSTRACT: In diploid segregation, each alternative allele has a 50% chance of being passed on to the offspring. Mutations in genes involved in the process of meiotic division or early stages of reproductive cell development can affect allele frequency in the gametes. In addition, competition among gametes and differential survival rates of gametes can lead to segregation distortion. In a recent transformation study, a male-sterile, female-sterile (MSFS) mutant was identified in the soybean cultivar, Williams. The mutant in heterozygous condition segregated 3 fertile:1 sterile in the progeny confirming monogenic inheritance. To map the lesion, we generated an F(2) mapping population by crossing the mutant (in heterozygous condition) with Minsoy (PI 27890). The F(2) progeny showed strong segregation distortion against the MSFS phenotype. The objectives of our study were to molecularly map the gene responsible for sterility in the soybean genome, to determine if the MSFS gene is a result of T-DNA insertion during Agrobacterium-mediated transformation, and to map the region that showed distorted segregation. The fertility/sterility locus was mapped to molecular linkage group (MLG) D1a (chromosome Gm01) using bulked segregant analysis. The closest marker, Satt531, mapped 9.4cM from the gene. Cloning of insertion sites for T-DNA in the mutant plants revealed that there are two copies of T-DNA in the genome. Physical locations of these insertion sites do not correlate with the map location of the MSFS gene, suggesting that MSFS mutation may not be associated with T-DNA insertions. Segregation distortion was most extreme at or around the st_A06-2/6 locus suggesting that sterility and segregation distortion are tightly linked attributes. Our results cue that the distorted segregation may be due to a gamete elimination system.
Plant Science 10/2012; 195:151-6. · 2.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: BACKGROUND: Nonhost resistance (NHR) provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Three Arabidopsis thaliana PEN (penetration deficient) genes, PEN1, 2 and 3 have been shown to provide NHR against the barley pathogen Blumeria graminis f. sp. hordei at the prehaustorial level. Arabidopsis pen1-1 mutant lacking the PEN1 gene is penetrated by the hemibiotrophic oomycete pathogen Phytophthora sojae, the causal organism of the root and stem rot disease in soybean. We investigated if there is any novel nonhost resistance mechanism in Arabidopsis against the soybean pathogen, P. sojae. RESULTS: The P. sojae susceptible (pss) 1 mutant was identified by screening a mutant population created in the Arabidopsis pen1-1 mutant that lacks penetration resistance against the non adapted barley biotrophic fungal pathogen, Blumeria graminis f. sp. hordei. Segregation data suggested that PEN1 is not epistatic to PSS1. Responses of pss1 and pen1-1 to P. sojae invasion were distinct and suggest that PSS1 may act at both pre- and post-haustorial levels, while PEN1 acts at the pre-haustorial level against this soybean pathogen. Therefore, PSS1 encodes a new form of nonhost resistance. The pss1 mutant is also infected by the necrotrophic fungal pathogen, Fusarium virguliforme, which causes sudden death syndrome in soybean. Thus, a common NHR mechanism is operative in Arabidopsis against both hemibiotrophic oomycetes and necrotrophic fungal pathogens that are pathogenic to soybean. However, PSS1 does not play any role in immunity against the bacterial pathogen, Pseudomonas syringae pv. glycinea, that causes bacterial blight in soybean. We mapped PSS1 to a region very close to the southern telomere of chromosome 3 that carries no known disease resistance genes. CONCLUSIONS: The study revealed that Arabidopsis PSS1 is a novel nonhost resistance gene that confers a new form of nonhost resistance against both a hemibiotrophic oomycete pathogen, P. sojae and a necrotrophic fungal pathogen, F. virguliforme that cause diseases in soybean. However, this gene does not play any role in the immunity of Arabidopsis to the bacterial pathogen, P. syringae pv. glycinea, which causes bacterial blight in soybean. Identification and further characterization of the PSS1 gene would provide further insights into a new form of nonhost resistance in Arabidopsis, which could be utilized in improving resistance of soybean to two serious pathogens.
BMC Plant Biology 06/2012; 12(1):87. · 3.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Centromeric regions of higher eukaryotes are comprised mainly of tandem and non-tandem repeat sequences with variable copy
number, spacing, order and orientation; are heterochromatic in nature, and are believed to be devoid of actively transcribing
genes. Here, we report an actively transcribing wheat homolog of HSP70 gene that maps in the functional wheat centromere, and copy number of which seems to change in response to centromeric breaks.
The HSP70 gene physically maps on the short arm of chromosomes 1A and 1D of Chinese Spring (CS) and 1R of rye. Whereas, on chromosome 1B in both ‘CS’ and Pavon background, the gene maps in the functional centromere as evident from its presence in both cytologically
confirmed true ditelosomic lines Dt1BS and Dt1BL. Sequence comparison of 11 ESTs showed three sequence patterns suggesting
that all three homoeologous copies of the gene are expressing. The cDNA-single stranded conformation polymorphism analysis
confirmed expression of the ‘CS’ 1B copy of the gene. Observed in two independently developed Dt1BL lines, the 1B copy number of the gene showed three to fivefold increase in response to chromosomal breaks around the centromere. Putative
gene duplications seem to involve large chromosomal segments as only one of the ten restriction enzymes used for DNA gel-blot
analysis showed unique extra fragment band in the Dt1BL line. Further investigations are warranted to uncover the nature and
mechanism of these duplications.
KeywordsCentromere-Deletion mapping-N-banding-SSCP-Wheat
Molecular Breeding 04/2012; 26(2):177-187. · 2.85 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Soybean is a major crop that is an important source of oil and proteins. A number of genetic linkage maps have been developed in soybean. Specifically, hundreds of simple sequence repeat (SSR) markers have been developed and mapped. Recent sequencing of the soybean genome resulted in the generation of vast amounts of genetic information. The objectives of this investigation were to use SSR markers in developing a connection between genetic and physical maps and to determine the physical distribution of recombination on soybean chromosomes. A total of 2,188 SSRs were used for sequence-based physical localization on soybean chromosomes. Linkage information was used from different maps to create an integrated genetic map. Comparison of the integrated genetic linkage maps and sequence based physical maps revealed that the distal 25% of each chromosome was the most marker-dense, containing an average of 47.4% of the SSR markers and 50.2% of the genes. The proximal 25% of each chromosome contained only 7.4% of the markers and 6.7% of the genes. At the whole genome level, the marker density and gene density showed a high correlation (R(2)) of 0.64 and 0.83, respectively with the physical distance from the centromere. Recombination followed a similar pattern with comparisons indicating that recombination is high in telomeric regions, though the correlation between crossover frequency and distance from the centromeres is low (R(2) = 0.21). Most of the centromeric regions were low in recombination. The crossover frequency for the entire soybean genome was 7.2%, with extremes much higher and lower than average. The number of recombination hotspots varied from 1 to 12 per chromosome. A high correlation of 0.83 between the distribution of SSR markers and genes suggested close association of SSRs with genes. The knowledge of distribution of recombination on chromosomes may be applied in characterizing and targeting genes.
PLoS ONE 01/2011; 6(7):e22306. · 4.09 Impact Factor
-
Jeremy Schmutz,
Steven B Cannon,
Jessica Schlueter,
Jianxin Ma,
Therese Mitros,
William Nelson,
David L Hyten,
Qijian Song,
Jay J Thelen,
Jianlin Cheng, [......],
Kazuo Shinozaki,
Henry T Nguyen,
Rod A Wing,
Perry Cregan,
James Specht,
Jane Grimwood,
Dan Rokhsar,
Gary Stacey,
Randy C Shoemaker,
Scott A Jackson
[show abstract]
[hide abstract]
ABSTRACT: Soybean (Glycine max) is one of the most important crop plants for seed protein and oil content, and for its capacity to fix atmospheric nitrogen through symbioses with soil-borne microorganisms. We sequenced the 1.1-gigabase genome by a whole-genome shotgun approach and integrated it with physical and high-density genetic maps to create a chromosome-scale draft sequence assembly. We predict 46,430 protein-coding genes, 70% more than Arabidopsis and similar to the poplar genome which, like soybean, is an ancient polyploid (palaeopolyploid). About 78% of the predicted genes occur in chromosome ends, which comprise less than one-half of the genome but account for nearly all of the genetic recombination. Genome duplications occurred at approximately 59 and 13 million years ago, resulting in a highly duplicated genome with nearly 75% of the genes present in multiple copies. The two duplication events were followed by gene diversification and loss, and numerous chromosome rearrangements. An accurate soybean genome sequence will facilitate the identification of the genetic basis of many soybean traits, and accelerate the creation of improved soybean varieties.
Nature 01/2010; 463(7278):178-83. · 36.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Systemic acquired resistance (SAR) is induced in non-inoculated leaves following infection with certain pathogenic strains. SAR is effective against many pathogens. Salicylic acid (SA) is a signaling molecule of the SAR pathway. The development of SAR is associated with the induction of pathogenesis related (PR) genes. Arabidopsis non-expressor of PR1 (NPR1) is a regulatory gene of the SA signal pathway 123. SAR in soybean was first reported following infection with Colletotrichum trancatum that causes anthracnose disease. We investigated if SAR in soybean is regulated by a pathway, similar to the one characterized in Arabidopsis.
Pathogenesis-related gene GmPR1 is induced following treatment of soybean plants with the SAR inducer, 2,6-dichloroisonicotinic acid (INA) or infection with the oomycete pathogen, Phytophthora sojae. In P. sojae-infected plants, SAR was induced against the bacterial pathogen, Pseudomonas syringae pv. glycinea. Soybean GmNPR1-1 and GmNPR1-2 genes showed high identities to Arabidopsis NPR1. They showed similar expression patterns among the organs, studied in this investigation. GmNPR1-1 and GmNPR1-2 are the only soybean homologues of NPR1and are located in homoeologous regions. In GmNPR1-1 and GmNPR1-2 transformed Arabidopsis npr1-1 mutant plants, SAR markers: (i) PR-1 was induced following INA treatment and (ii) BGL2 following infection with Pseudomonas syringae pv. tomato (Pst), and SAR was induced following Pst infection. Of the five cysteine residues, Cys82, Cys150, Cys155, Cys160, and Cys216 involved in oligomer-monomer transition in NPR1, Cys216 in GmNPR1-1 and GmNPR1-2 proteins was substituted to Ser and Leu, respectively.
Complementation analyses in Arabidopsis npr1-1 mutants revealed that homoeologous GmNPR1-1 and GmNPR1-2 genes are orthologous to Arabidopsis NPR1. Therefore, SAR pathway in soybean is most likely regulated by GmNPR1 genes. Substitution of Cys216 residue, essential for oligomer-monomer transition of Arabidopsis NPR1, with Ser and Leu residues in GmNPR1-1 and GmNPR1-2, respectively, suggested that there may be differences between the regulatory mechanisms of GmNPR1 and Arabidopsis NPR proteins.
BMC Plant Biology 09/2009; 9:105. · 3.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Soybean [Glycine max (L.) Merr.] is self-pollinated. To produce large quantities of hybrid seed, insect-mediated cross-pollination is necessary. An efficient nuclear male-sterile system for hybrid seed production would benefit from molecular and/or phenotypic markers linked to male fertility/sterility loci to facilitate early identification of phenotypes. Nuclear male-sterile, female-fertile ms3 mutant is a single recessive gene and displays high outcrossed seed set with pollinators. Our objective was to map the ms3 locus. A segregating population of 150 F(2) plants from Minsoy (PI 27890) x T284H, Ms3ms3 (A00-68), was screened with 231 simple sequence repeat markers. The ms3 locus mapped to molecular linkage group (MLG) D1b (Gm02) and is flanked by markers Satt157 and Satt542, with a distance of 3.7 and 12.3 cM, respectively. Female-partial sterile-1 (Fsp1) and the Midwest Oilseed male-sterile (msMOS) mutants previously were located on MLG D1b. msMOS and Fsp1 are independent genes located very close to each other. All 3 genes are located in close proximity of Satt157. We believe that this is the first report of clustering of fertility-related genes in plants. Characterization of these closely linked genes may help in understanding the evolutionary relationship among them.
The Journal of heredity 08/2009; 100(5):565-70. · 2.05 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Oleic acid is one of the three major unsaturated fatty acids in soybean oil. Expression of the embryo-specific Fad2-1 gene correlates with fatty acid biosynthesis and oil deposition in developing seeds. Elevated levels of oleate in the X-ray-induced
mutant line M23 have been shown to be associated with the deletion of a Fad2-1 gene. In soybean, two homologs of the Fad2-1 gene, termed Fad2-1a (L43920) and Fad2-1b (AY611472), presumably encode functional embryo-specific fatty acid desaturase. The objectives of this investigation were
to determine which copy of the Fad2-1 gene is associated with the increased oleate content in the mutant line and what is the relative transcript abundance of
these two embryo-specific genes. PCR and DNA blot analyses showed that increased oleate content in M23 mutant was associated
with the deletion of Fad2-1a. These results were further validated using five independent soybean populations developed by crossing mid-oleate and normal-oleate
parents. Investigation of the soybean expressed sequence tag database and reverse transcription PCR analyses revealed that
Fad2-1b is the predominantly transcribed copy of the Fad2-1 gene. We hypothesize that null mutation in Fad2-1b in the fad2-1a mutant background should further elevate the oleic contents of soybean oil.
Journal of Oil & Fat Industries 01/2007; 84(3):229-235. · 1.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Resistance of soybean against the oomycete pathogen Phytophthora sojae is conferred by a series of Rps genes. We have characterized a disease resistance gene-like sequence NBSRps4/6 that was introgressed into soybean lines along with Rps4 or Rps6. High-resolution genetic mapping established that NBSRps4/6 cosegregates with Rps4. Two mutants, M1 and M2, showing rearrangements in the NBSRps4/6 region were identified from analyses of 82 F(1)'s and 201 selfed HARO4272 plants containing Rps4. Fingerprints of these mutants are identical to those of HARO4272 for 176 SSR markers representing the whole genome except the NBSRps4/6 region. Both mutants showed a gain of race specificities, distinct from the one encoded by Rps4. To investigate the possible mechanism of gain of Phytophthora resistance in M1, the novel race specificity was mapped. Surprisingly, the gene encoding this resistance mapped to the Rps3 region, indicating that this gene could be either allelic or linked to Rps3. Recombinant analyses have shown that deletion of NBSRps4/6 in M1 is associated with the loss of Rps4 function. The NBSRps4/6 sequence is highly transcribed in etiolated hypocotyls expressing the Phytophthora resistance. It is most likely that a copy of the NBSRps4/6 sequence is the Rps4 gene. Possible mechanisms of the deletion in the NBSRps4/6 region and introgression of two unlinked Rps genes into Harosoy are discussed.
Genetics 01/2005; 168(4):2157-67. · 4.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The objectives of this study were to isolate and physically localize expressed resistance (R) genes on wheat chromosomes. Irrespective of the host or pest type, most of the 46 cloned R genes from 12 plant species share a strong sequence similarity, especially for protein domains and motifs. By utilizing this structural similarity to perform modified RNA fingerprinting and data mining, we identified 184 putative expressed R genes of wheat. These include 87 NB/LRR types, 16 receptor-like kinases, and 13 Pto-like kinases. The remaining were seven Hm1 and two Hs1(pro-1) homologs, 17 pathogenicity related, and 42 unique NB/kinases. About 76% of the expressed R-gene candidates were rare transcripts, including 42 novel sequences. Physical mapping of 121 candidate R-gene sequences using 339 deletion lines localized 310 loci to 26 chromosomal regions encompassing approximately 16% of the wheat genome. Five major R-gene clusters that spanned only approximately 3% of the wheat genome but contained approximately 47% of the candidate R genes were observed. Comparative mapping localized 91% (82 of 90) of the phenotypically characterized R genes to 18 regions where 118 of the R-gene sequences mapped.
Genetics 02/2004; 166(1):461-81. · 4.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: By physically mapping 3025 loci including 252 phenotypically characterized genes and 17 quantitative trait loci (QTLs) relative to 334 deletion breakpoints, we localized the gene-containing fraction to 29% of the wheat genome present as 18 major and 30 minor gene-rich regions (GRRs). The GRRs varied both in gene number and density. The five largest GRRs physically spanning <3% of the genome contained 26% of the wheat genes. Approximate size of the GRRs ranged from 3 to 71 Mb. Recombination mainly occurred in the GRRs. Various GRRs varied as much as 128-fold for gene density and 140-fold for recombination rates. Except for a general suppression in 25-40% of the chromosomal region around centromeres, no correlation of recombination was observed with the gene density, the size, or chromosomal location of GRRs. More than 30% of the wheat genes are in recombination-poor regions thus are inaccessible to map-based cloning.
Nucleic Acids Research 02/2004; 32(12):3546-65. · 8.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report the construction and characterization of the first soybean yeast artificial chromosome (YAC) library using high-molecular weight DNA isolated from leaf nuclei of the cultivar Conrad 94 that carries Phytophthora resistance genes Rps1-k and Rps6. The quality of this library has been evaluated through analysis of 393 randomly selected YAC clones. The library consists of 36864 clones, of which approximately 19956 carry single soybean YACs with an average size of about 285 kb. The library represents approximately five soybean genome equivalents. The probability of finding any soybean sequences from this library is about 0.99. The library was screened for 43 SSR markers representing the whole soybean genome. We were able to identify positive YAC pools for 95% of the SSR markers. Two YAC clones carrying molecular markers linked to the Rps6 gene were identified. The YAC library reported here would be a useful resource for map-based cloning of agronomically important soybean genes and also to complement the effort towards construction of the physical map for the soybean genome.
Functional and Integrative Genomics 01/2004; 3(4):153-9. · 2.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report the construction and characterization of the first soybean yeast artificial chromosome (YAC) library using high-molecular weight DNA isolated from leaf nuclei of the cultivar Conrad 94 that carries Phytophthora resistance genes Rps1-k and Rps6. The quality of this library has been evaluated through analysis of 393 randomly selected YAC clones. The library consists of 36,864 clones, of which 19,956 carry single soybean YACs with an average size of about 285kb. The library represents approximately five soybean genome equivalents. The probability of finding any soybean sequences from this library is about 0.99. The library was screened for 43 SSR markers representing the whole soybean genome. We were able to identify positive YAC pools for 95% of the SSR markers. Two YAC clones carrying molecular markers linked to the Rps6 gene were identified. The YAC library reported here would be a useful resource for map-based cloning of agronomically important soybean genes and also to complement the effort towards construction of the physical map for the soybean genome.
Functional and Integrative Genomics 11/2003; 3(4):153-159. · 2.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Plant Molecular Biology
49: 791–804, 2002 Table 1 of this article was wrongly printed. The correct version is printed overleaf.
Plant Molecular Biology 08/2002; 50(1):151-153. · 4.15 Impact Factor
-
Nils Rostoks,
Yong-Jin Park,
Wusirika Ramakrishna,
Jianxin Ma,
Arnis Druka,
Bryan A Shiloff,
Phillip J SanMiguel,
Zeyu Jiang,
Robert Brueggeman, Devinder Sandhu,
Kulvinder Gill,
Jeffrey L Bennetzen,
Andris Kleinhofs
[show abstract]
[hide abstract]
ABSTRACT: Barley (Hordeum vulgare L.) is one of the most important large-genome cereals with extensive genetic resources available in the public sector. Studies of genome organization in barley have been limited primarily to genetic markers and sparse sequence data. Here we report sequence analysis of 417.5 kb DNA from four BAC clones from different genomic locations. Sequences were analyzed with respect to gene content, the arrangement of repetitive sequences and the relationship of gene density to recombination frequencies. Gene densities ranged from 1 gene per 12 kb to 1 gene per 103 kb with an average of 1 gene per 21 kb. In general, genes were organized into islands separated by large blocks of nested retrotransposons. Single genes in apparent isolation were also found. Genes occupied 11% of the total sequence, LTR retrotransposons and other repeated elements accounted for 51.9% and the remaining 37.1% could not be annotated.
Functional and Integrative Genomics 06/2002; 2(1-2):51-9. · 2.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Deletion line-based high-density physical maps revealed that the wheat (Triticum aestivum) genome is partitioned into gene-rich and -poor compartments. Available deletion lines have bracketed the gene-containing regions to about 10% of the genome. Emerging sequence data suggest that these may further be partitioned into "mini" gene-rich and gene-poor regions. An average of about 10% of each gene-rich region seem to contain genes. Sequence analyses in various species suggest that uneven distribution of genes may be a characteristic of all grasses and perhaps all higher organisms. Comparison of the physical maps with genetic linkage maps showed that recombination in wheat and barley (Hordeum vulgare) is confined to the gene-containing regions. Number of genes, gene density, and the extent of recombination vary greatly among the gene-rich regions. The gene order, relative region size, and recombination are highly conserved within the tribe Triticeae and moderately conserved within the family. Gene-poor regions are composed of retrotransposon-like non-transcribing repeats and pseudogenes. Direct comparisons of orthologous regions indicated that gene density in wheat is about one-half compared with rice (Oryza sativa). Genome size difference between wheat and rice is, therefore, mainly because of amplification of the gene-poor regions. Presence of species-, genera-, and family-specific repeats reveal a repeated invasion of the genomes by different retrotransposons over time. Preferential transposition to adjacent locations and presence of vital genes flanking a gene-rich region may have restricted retrotransposon amplification to gene-poor regions, resulting into tandem blocks of non-transcribing repeats. Insertional inactivation by adjoining retro-elements and selection seem to have played a major role in stabilizing genomes.
Plant physiology 04/2002; 128(3):803-11. · 6.53 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Wheat genes are present in physically small, gene-rich regions, interspersed by gene-poor blocks of retrotransposon-like repetitive sequences. One of the largest gene-rich regions is present around fraction length (FL) 0.8 of the short arm of wheat homoeologous group 1 chromosomes and is called '1S0.8 region'. The objective of this study was to reveal the structural and functional organization of the '1S0.8 region' in various Triticeae and other Poaceae species. Consensus genetic linkage maps of the '1S0.8 region' were constructed for wheat, barley, and rye by combining mapping information from 16, 11, and 12 genetic linkage maps, respectively. The consensus genetic linkage maps were compared with each other and with a consensus physical map of wheat homoeologous group 1. Comparative analyses localized 75 agronomically important genes to the '1S0.8 region'. This high-resolution comparison revealed exceptions to the rule of conserved gene synteny, established using low-resolution marker comparisons. Small rearrangements such as duplications, deletions, and inversions were observed among species. Proportion ofchromosomal recombination occurring in the '1S0.8 region' was very similar among species. Within the gene-rich region, the extent of recombination was highly variable but the pattern was similar among species. Relative recombination among markers was similar except for a few loci where drastic differences were observed among species. Chromosomal rearrangements did not always change the extent of recombination for the region. Differences in gene order and relative recombination were the least between wheat and barley, and were the highest between wheat and oat.
Plant Molecular Biology 48(5-6):791-804. · 4.15 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In soybean [Glycine max (L.) Merr.], manual cross-pollination to produce large quantities of hybrid seed is difficult and time consuming. Identification of an environmentally stable male-sterility system could make hybrid seed production commercially valuable. In soybean, 2 environmentally sensitive male-sterile, female-fertile mutants (ms8 and msp) have been identified. Inheritance studies showed that sterility in both mutants is inherited as a single gene. The objectives of this study were to 1) confirm that msp and ms8 are independent genes; 2) identify the soybean chromosomes that contain the msp and the ms8 genes using bulked segregant analyses (BSAs); and 3) make a genetic linkage map of the regions containing these genes. Mapping populations consisting of 176 F(2) plants for ms8 and 134 F(2) plants for msp were generated. BSA revealed that Sat_389 and Satt172 are closely associated markers with ms8 and msp, respectively. Map location of Sat_389 suggested that the ms8 gene is located on chromosome 7; molecular linkage group (MLG) M. Map location of Satt172 indicated that the msp gene is located on chromosome 2 (MLG Dlb). Genetic linkage maps developed using F(2) populations revealed that ms8 is flanked by a telomere and Sat_389 and msp is flanked by Sat_069 and GMES4176. The region between the telomere and Sat_389 is physically 160 Kb. Soybean sequence information revealed that there are 13 genes present in that region. Protein BLASTP analyses revealed that homologs of 3 of the 13 genes are known to a play role in cell division, suggesting putative candidates for ms8.
The Journal of heredity 102(1):11-6. · 2.05 Impact Factor
