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Karyotypes of three accessions of Hordeum chilense (H1, H16, and H7), Hordeum vulgare, and Triticum aestivum were characterized by physical mapping of several repetitive sequences. A total of 14 repetitive sequences were used as probes for fluorescence in situ hybridization (FISH) with the aim of identifying inter- and intraspecies polymorphisms. The (AG)12 and 4P6 probes only produced hybridization signals in wheat, the BAC7 probe only hybridized to the centromeric region of H. vulgare, and the pSc119.2 probe hybridized to both wheat and H. chilense, but not to H. vulgare. The remaining repetitive sequences used in this study produced a hybridization signal in all the genotypes. Probes pAs1, pTa-535, pTa71, CCS1, and CRW were much conserved, showing no significant polymorphism among the genotypes studied. Probes GAA, (AAC)5, (CTA)5, HvT01, and pTa794 produced the most different hybridization pattern. We identified large polymorphisms in the three accessions of H. chilense studied, supporting the proposal of the existence of different groups inside species of H. chilense. The set of probes described in this work allowed the identification of every single chromosome in all three species, providing a complete cytogenetic karyotype of H. chilense, H. vulgare, and T. aestivum chromosomes, which could be useful in wheat and tritordeum breeding programs. [ABSTRACT FROM AUTHOR]

Key message: A complete set of six compensating Robertsonian translocation chromosomes involving barley chromosome 7H and three chromosomes of hexaploid wheat was produced. Grain β-glucan content increased in lines containing 7HL. Abstract: Many valuable genes for agronomic performance, disease resistance and increased yield have been transferred from relative species to wheat ( Triticum aestivum L.) through whole-arm Robertsonian translocations (RobT). Although of a great value, the sets of available translocations from barley ( Hordeum vulgare L.) are limited. Here, we present the production of a complete set of six compensating RobT chromosomes involving barley chromosome 7H and three group-7 chromosomes of wheat. The barley group-7 long-arm RobTs had a higher grain β-glucan content compared to the wheat control. The β-glucan levels varied depending on the temperature and were higher under hot conditions. Implicated in this increase, the barley cellulose synthase-like F6 gene ( CslF6) responsible for β-glucan synthesis was physically mapped near the centromere in the long arm of barley chromosome 7H. Likewise, wheat CslF6 homoeologs were mapped near the centromere in the long arms of all group-7 wheat chromosomes. With the set of novel wheat-barley translocations, we demonstrate a valuable increase of β-glucan, along with a resource of genetic stocks that are likely to carry many other important genes from barley into wheat. [ABSTRACT FROM AUTHOR]

Leaf sheath hairiness is a morphological trait associated with various advantages, including tolerance to both abiotic and biotic stresses, thereby increasing yield. Understanding the genetic basis of this trait in barley can therefore improve the agronomic performance of this economically important crop. We scored leaf sheath hairiness in a two-year field trial in 1,420 BC1S3 lines from the wild barley nested association mapping (NAM) population HEB-25. Leaf sheath hairiness segregated in six out of 25 families with the reference parent Barke being glabrous. We detected the major hairy leaf sheath locus Hs (syn. Hsh) on chromosome 4H (111.3 cM) with high precision. The effects of the locus varied across the six different wild barley donors, with donor of HEB family 11 conferring the highest score of leaf sheath hairiness. Due to the high mapping resolution present in HEB-25, we were able to discuss physically linked pentatricopeptide repeat genes and subtilisin-like proteases as potential candidate genes underlying this locus. In this study, we proved that HEB-25 provides an appropriate tool to further understand the genetic control of leaf sheath hairiness in barley. Furthermore, our work represents a perfect starting position to clone the gene responsible for the 4H locus observed. [ABSTRACT FROM AUTHOR]

We used the 'Baronesse'/'Full Pint' doubled haploid population to analyse the genetic factors controlling flowering date under South American conditions. Both parents have similar heading dates, but the population shows transgressive segregation. Two genes, eps2S on chromosome 2H and sdw1 on chromosome 3H, explained most of the phenotypic variation for anthesis date, with the later allele carried by 'Baronesse' and 'Full Pint' , respectively. Both effects were completely additive with no interaction. We studied three plant developmental periods: seedling emergence to tillering (Z10-Z20), tillering (Z20-Z30) and end of tillering to anthesis (Z30-Z49) under field conditions at three contrasting planting dates. Z10-Z20 was also measured under semi-controlled conditions. eps2S controlled Z30-Z49 periods, while sdw1 controlled Z20-Z30. Each of the two genes for the end-point phenotype-anthesis date-was a determinant of flowering at a different developmental stage. No gene x planting date interactions were detected. [ABSTRACT FROM AUTHOR]

Key message: The barley eceriferum-b.2 ( cer-b.2) mutant produces glossy leaf sheaths and is deficient in the cuticular wax component 14,16-hentriacontanedione. The mutated gene maps to a 1.3-cM interval on chromosome 3HL flanked by the genes MLOC_10972 and MLOC_69561. Abstract: The cuticular wax coating of leaves and stems in many grass species is responsible for the plants' glaucous appearance. A major component of the wax is a group of β-diketone compounds. The barley eceriferum-b.2 ( cer-b.2) mutant produces glossy leaf sheaths and is deficient for the compound 14,16-hentriacontanedione. A linkage analysis based on 708 gametes allowed the gene responsible for the mutant phenotype to be mapped to a 1.3-cM interval on chromosome 3HL flanked by the two genes MLOC_10972 and _69561. The product of the wild type allele may represent a step in the β-diketone synthesis pathway. [ABSTRACT FROM AUTHOR]

A better understanding of the developmental plan of a cereal spike is of relevance when designing the plant for the future, in which innovative traits can be implemented through pre-breeding strategies. Barley developmental mutants can be a Mendelian solution for identifying genes controlling key steps in the establishment of the spike morphology. Among cereals, barley (Hordeum vulgare L.) is one of the best investigated crop plants and is a model species for the Triticeae tribe, thanks to several characteristics, including, among others, its adaptability to a wide range of environments, its diploid genome, and its self-pollinating mating system, as well as the availability of its genome sequence and a wide array of genomic resources. Among them, large collections of natural and induced mutants have been developed since the 1920s, with the aim of understanding developmental and physiological processes and exploiting mutation breeding in crop improvement. The collections are not only comprehensive in terms of single Mendelian spike mutants, but with regards to double and triple mutants derived from crosses between simple mutants, as well as near isogenic lines (NILs) that are useful for genetic studies. In recent years the integration of the most advanced omic technologies with historical mutation-genetics research has helped in the isolation and validation of some of the genes involved in spike development. New interrogatives have raised the question about how the behavior of a single developmental gene in different genetic backgrounds can help in understanding phenomena like expressivity, penetrance, phenotypic plasticity and instability. In this paper, some genetic and epigenetic studies on this topic are reviewed. [ABSTRACT FROM AUTHOR]

The pairing behaviour of the individual chromosome arms of Hordeum vulgare (Hv) with their homoeologous arms of H. bulbosum (Hb) at metaphase I of meiosis in tetraploid Hb × Hv hybrids and the frequencies of recombined Hv chromosome arms in selfed offspring were studied on differentially visualized chromosomes after fluorescent in situ hybridisation. The frequencies of paired Hv-Hb arms in the F2 and F3 hybrids were correlated with the frequencies of recombined Hv chromosomes in progenies. Self-generation of hybrids, the number of Hv and Hb chromosomes, and the number of recombined Hv chromosomes of the hybrids strongly influenced the Hv - Hb pairing frequency in meiosis. Within the offspring of F2 and F3 hybrids both Hv plants and hybrids were detected. In contrast, all progenies of the F4 hybrid were hybrids which exhibited centromere misdivisions. The highest frequencies of homoeologous pairing in hybrids and most recombinants were obtained for the barley chromosome 1HL. Recombinants for 4HL, 5HS, 6HS, and 7HS were rarely found. Meiotic pairing and recombinants involving chromosome 1HS were never observed. The results of this study demonstrate that fertile tetraploid interspecific hybrids with a high intergenomic pairing at meiosis are valuable basic material for introgression breeding in barley. [ABSTRACT FROM AUTHOR]

Key message: This study describes the generation, screening, genetic and molecular characterization, and high-resolution mapping of barley mutants susceptible to stem rust ( Puccinia graminis f. sp. tritici ) races MCCF and HKHJ. Abstract: A single gene, Rpg1, has protected barley cultivars against many races of stem rust pathogen ( Puccinia graminis f. sp. tritici) for the last 70 years in the United States and Canada. To identify signaling components of protein product RPG1, we employed a mutagenesis approach. Using this approach, six mutants exhibiting susceptibility to Puccinia graminis f. sp. tritici races MCCF and HKHJ were identified in the gamma irradiated M population of resistant cultivar Morex, which carries Rpg1 on chromosome 7H. The mutants retained a functional Rpg1 gene and an apparently functional protein, suggesting that the mutated genes were required for downstream or upstream signaling. Selected mutants were non-allelic, hence each mutant represents a unique gene. Low and high-resolution genetic mapping of the rpr2 mutant identified chromosome 6H (bin 6) as the location of the mutated gene. The target region was reduced to 0.6 cM and gene content analyzed. Based on the published barley genomic sequence, the target region contains approximately 157 genes, including a set that encodes putative leucine-rich receptor-like protein kinases, which may be strong candidates for the gene of interest. Overall, this study presents a strong platform for future map-based cloning of genes identified in this mutant screen. [ABSTRACT FROM AUTHOR]

Four members of the UDP-Ara mutase (UAM) gene family from barley have been isolated and characterized, and their map positions on chromosomes 2H, 3H, and 4H have been defined. When the genes are expressed in Escherichia coli, the corresponding HvUAM1, HvUAM2, and HvUAM3 proteins exhibit UAM activity, and the kinetic properties of the enzymes have been determined, including Km, Kcat, and catalytic efficiencies. However, the expressed HvUAM4 protein shows no mutase activity against UDP-Ara or against a broad range of other nucleotide sugars and related molecules. The enzymic data indicate therefore that the HvUAM4 protein may not be a mutase. However, the HvUAM4 gene is transcribed at high levels in all the barley tissues examined, and its transcript abundance is correlated with transcript levels for other genes involved in cell wall biosynthesis. The UDP-l-Arap ? UDP-l-Araf reaction, which is essential for the generation of the UDP-Araf substrate for arabinoxylan, arabinogalactan protein, and pectic polysaccharide biosynthesis, is thermodynamically unfavorable and has an equilibrium constant of 0.02. Nevertheless, the incorporation of Araf residues into nascent polysaccharides clearly occurs at biologically appropriate rates. The characterization of the HvUAM genes opens the way for the manipulation of both the amounts and fine structures of heteroxylans in cereals, grasses, and other crop plants, with a view toward enhancing their value in human health and nutrition, and in renewable biofuel production. [ABSTRACT FROM AUTHOR]

Barley ( Hordeum vulgare) is a crop of global significance. However, a third of the genes of barley are largely inaccessible to conventional breeding programmes as crossovers are localised to the ends of the chromosomes. This work examines whether crossovers can be shifted to more proximal regions simply by elevating growth temperature., We utilised a genome-wide marker set for linkage analysis combined with cytological mapping of crossover events to examine the recombination landscape of plants grown at different temperatures., We found that barley shows heterochiasmy, that is, differences between female and male recombination frequencies. In addition, we found that elevated temperature significantly changes patterns of recombination in male meiosis only, with a repositioning of Class I crossovers determined by cytological mapping of Hv MLH3 foci. We show that the length of synaptonemal complexes in male meiocytes increases in response to temperature., The results demonstrate that the distribution of crossover events are malleable and can be shifted to proximal regions by altering the growth temperature. The shift in recombination is the result of altering the distribution of Class I crossovers, but the higher recombination at elevated temperatures is potentially not the result of an increase in Class I events. [ABSTRACT FROM AUTHOR]

Little is known about the genetic divergence in the chromosomal regions with domesticated and non-domesticated genes. The objective of our study is to examine the effect of natural selection on shaping genetic diversity of chromosome region with domesticated and non-domesticated genes in barley using 110 SSR markers. Comparison of the genetic diversity loss between wild and cultivated barley for each chromosome showed that chromosome 5H had the highest divergence of 35.29%, followed by 3H, 7H, 4H, 2H, 6H. Diversity ratio was calculated as (diversity of wild type – diversity of cultivated type)/diversity of wild type×100%. It was found that diversity ratios of the domesticated regions on 5H, 1H and 7H were higher than those of non-domesticated regions. Diversity ratio of the domesticated region on 2H and 4H is similar to that of non-domesticated region. However, diversity ratio of the domesticated region on 3H is lower than that of non-domesticated region. Averaged diversity among six chromosomes in domesticated region was 33.73% difference between wild and cultivated barley, and was 27.56% difference in the non-domesticated region. The outcome of this study advances our understanding of the evolution of crop chromosomes. [ABSTRACT FROM AUTHOR]

Background Barley is an important cereal crop cultivated for malt and ruminant feed and in certain regions it is used for human consumption. It is vulnerable to numerous foliar diseases including barley leaf rust caused by the pathogen Puccinia hordei. Results A temporarily designated resistance locus RphCantala (RphC) identified in the Australian Hordeum vulgare L. cultivar 'Cantala' displayed an intermediate to low infection type (";12 = N") against the P. hordei pathotype 253P- (virulent on Rph1, Rph2, Rph4, Rph6, Rph8 and RphQ). Phenotypic assessment of a 'CI 9214' (susceptible) x 'Stirling' (RphC) (CI 9214/Stirling) doubled haploid (DH) population at the seedling stage using P. hordei pathotype 253P-, confirmed that RphC was monogenically inherited. Marker-trait association analysis of RphC in the CI 9214/Stirling DH population using 4,500 DArT-seq markers identified a highly significant (-log10Pvalue > 17) single peak on the long arm of chromosome 5H (5HL). Further tests of allelism determined that RphC was genetically independent of Rph3, Rph7, Rph11, Rph13 and Rph14, and was an allele of Rph12 (Rph9.z), which also maps to 5HL. Conclusion Multipathotype tests and subsequent pedigree analysis determined that 14 related Australian barley varieties (including 'Stirling' and 'Cantala') carry RphC and that the likely source of this resistance is via a Czechoslovakian landrace LV-Kvasice-NA-Morave transferred through common ancestral cultivars 'Hanna' and 'Abed Binder'. RphC is an allele of Rph12 (Rph9.z) and is therefore designated Rph9.am. Bioinformatic analysis using sequence arrays from DArT-seq markers in linkage disequilibrium with Rph9.am identified possible candidates for further gene cloning efforts and marker development at the Rph9 / Rph12 / Rph9.am locus. [ABSTRACT FROM AUTHOR]

Meiotic recombination results in the formation of cytological structures known as chiasmata at the sites of genetic crossovers (COs). The formation of at least one chiasma/CO between homologous chromosome pairs is essential for accurate chromosome segregation at the first meiotic division as well as for generating genetic variation. Although DNA double-strand breaks, which initiate recombination, are widely distributed along the chromosomes, this is not necessarily reflected in the chiasma distribution. In many species there is a tendency for chiasmata to be distributed in favored regions along the chromosomes, whereas in others, such as barley and some other grasses, chiasma localization is extremely pronounced. Localization of chiasma to the distal regions of barley chromosomes restricts the genetic variation available to breeders. Studies reviewed herein are beginning to provide an explanation for chiasma localization in barley. Moreover, they suggest a potential route to manipulating chiasma distribution that could be of value to plant breeders. [ABSTRACT FROM AUTHOR]

Fluorescence in situ hybridization (FISH) has been an efficient way for integrating physical and genetic maps of various small genomes like rice, sorghum and Brachypodium; whereas in the large genomes like barley, the repetitive nature of the genome complicates the generation and detection of single-copy FISH probes. Here, we used exemplarily physical map contigs of a defined interval of the long arm of barley chromosome 2H to evaluate the potential of FISH-based mapping as a supportive means for genetic anchoring of the physical map and to resolve the linear order of contigs along the respective chromosome. Repeat-free FISH probes corresponding to 8 previously anchored BAC contigs were specifically allocated to chromosome 2H. This represented an almost 90% success rate in single-copy FISH probe development. FISH mapping of contigs located in the subtelomeric region revealed an over-performance of genetic mapping over FISH for physical map anchoring. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

We dissected barley chromosomes 1H and 6H added to common wheat by the gametocidal system and identified structural changes of the chromosomes by fluorescence in situ hybridization and genomic in situ hybridization. We found five aberrations of chromosome 1H, all of which lacked the long arm: one small fragment with the subtelomeric HvT01 sequence, one terminal deletion, and three telocentric chromosomes of the short arm. We established 33 dissection lines carrying single aberrant 6H chromosomes, of which 15 were deletions, 16 were translocations and two were isochromosomes. We conducted PCR analysis of the aberrant barley chromosomes using 75 and 81 EST markers specific to chromosomes 1H and 6H, respectively. This enabled us to construct a cytological map of chromosome 6H and to compare it to the previously reported genetic map and also to the physical map, which were released by the International Barley Genome Sequencing Consortium. The marker orders on the three maps were largely in agreement. The cytological map had better resolution in the proximal region of chromosome 6H than the corresponding genetic map. We discuss some of the discrepancies in marker order between the three maps that might be due to intraspecific polymorphism and gene duplication, as well as to technical problems inherent in the physical mapping process. [ABSTRACT FROM AUTHOR]

The greenbug, Schizaphis graminum ( Rondani) is an extremely damaging aphid pest of barley ( Hordeum vulgare L.) particularly in the southern Great Plains of the USA. The simply inherited, dominant resistance gene Rsg1 is in all greenbug-resistant US barley cultivars. In this study, we conducted molecular mapping of Rsg1 using an F2:3 population derived from a cross between the greenbug-resistant Post 90*4/ R015 and susceptible CI2260 inbred lines. Segregation of host responses to greenbug biotype E infestation confirmed that a single dominant gene is responsible for greenbug resistance in Post 90*4/ R015. Simple sequence repeat ( SSR) markers evenly distributed along the seven barley chromosomes were employed for the construction of a framework genetic map. Linkage analysis placed the Rsg1 locus in the long arm of chromosome 3 H (3 HL) flanked by SSR markers Bmag0877 and GBM1420 that were 35 c M apart. Polymorphic single-nucleotide polymorphism ( SNP) markers in 3 HL were identified from an Illumina Golden Gate SNP assay and used for targeted mapping to locate Rsg1 to an 8.4-cM interval. Comparative analysis identified syntenic genomic regions in Brachypodium distachyon chromosome 2, in which 37 putative genes were annotated including a NB- LRR-type resistance gene homologue that may be a potential candidate gene for the Rsg1 locus of barley. Results from this study offer a starting point for fine mapping and cloning of this aphid resistance gene in barley. [ABSTRACT FROM AUTHOR]

Abstract: Plant height and spike length and angle are important agronomic traits in the production of barley (Hordeum vulgare L.) due to strong correlations with lodging and disease. The objective of this study was to use QTL analysis to identify genetic regions associated with each trait in a recombinant inbred line (RIL) mapping population derived from a cross of Falcon by Azhul. Falcon is a spring six-row hulless feed barley with long spikes displaying obtuse angles, while Azhul is a spring dwarf, six-row hulless food barley with short spikes displaying acute angles. The population was genotyped using SNP, DArT and SSR markers and quantitative trait loci (QTL) were detected on chromosomes 2H (102.8cM, spike length), 3H (89.2cM, plant height and 38.2, spike angle and length), 4H (19.0cM, spike length), and 5H (106.7cM, spike angle). In conclusion, we developed a barley genetic map, which incorporated SNP, DArT and SSR markers, for detection of height and spike length and angle QTL. Three spike angle, one spike length and one plant height QTL were novel and by using comparative genomics we identified possible candidate genes involved in gibberellic acid signaling and auxin- and ethylene-responsive pathways. This knowledge can be used to generate suitable markers for barley breeding improvement. [Copyright &y& Elsevier]

Gametocidal (Gc) chromosomes induce various types of chromosomal mutations during gametogenesis in the chromosomes of common wheat and alien chromosomes added to common wheat. However, it is not yet known whether the Gc chromosome causes aberrations at the nucleotide level because mutations caused by Gc chromosomes have been studied only by cytological screening. In order to know whether the Gc chromosome induces point mutations, we conducted PCR analysis and sequencing with the progeny of a common wheat line that is disomic for barley chromosome 2H and monosomic for Gc chromosome 2C. We analyzed 18 2H-specific EST sequences using 81 progeny plants carrying a cytologically normal-appearing 2H chromosome and found no nucleotide changes in the analyzed 1,419 sequences (in total 647,075 bp). During this analysis, we found six plants for which some ESTs could not be PCR amplified, suggesting the presence of chromosomal mutations in these plants. The cytological and PCR analyses of the progeny of the six plants confirmed the occurrence of chromosomal mutations in the parental plants. These results suggested that the Gc chromosome mostly induced chromosomal aberrations, not nucleotide changes, and that the Gc-induced chromosomal mutations in the six plants occurred after fertilization. [ABSTRACT FROM AUTHOR]

Artificially induced translocation stocks have been used to physically map the barley genome; however, natural translocations are extremely uncommon in cultivated genotypes. Albacete is a barley variety widely grown in recent decades in Spain and carrying a reciprocal translocation which obviously does not affect its agronomical fitness. This translocation has been characterized by a combination of cytological and molecular genetic approaches. Firstly, recombination frequencies between markers on chromosomes 1H and 3H were estimated to determine the boundaries of the reciprocal interchange. Secondly, 1H-3H wheat barley telosome addition lines were used to assign selected markers to chromosome arms. Thirdly, fluorescence in situ hybridization (FISH) with rDNA probes (5S and 18S-5.8S-26S) and microsatellite probes [(ACT), (AAG) and (CAG)] was used to determine the locations of the translocation breakpoints more precisely. Fourthly, fine-mapping of the regions around the translocation breakpoints was used to increase the marker density for comparative genomics. The results obtained in this study indicate that the translocation is quite large with breakpoints located on the long arms of chromosomes 1H and 3H, between the pericentromeric (AAG) bands and above the (ACT) interstitial distal bands, resulting in the reciprocal translocation 1HS.1HL-3HL and 3HS.3HL-1HL. The gene content around the translocation breakpoints could be inferred from syntenic relationships observed among different species from the grass family Poaceae (rice, Sorghum and Brachypodium) and was estimated at approximately 1,100 and 710 gene models for 1H and 3H, respectively. Duplicated segments between chromosomes Os01 and Os05 in rice derived from ancestral duplications within the grass family overlap with the translocation breakpoints on chromosomes 1H and 3H in the barley variety Albacete. [ABSTRACT FROM AUTHOR]

Engineered minichromosomes offer an enormous opportunity to plant biotechnology as they have the potential to simultaneously transfer and stably express multiple genes. Following a top-down approach, we truncated endogenous chromosomes in barley ( Hordeum vulgare) by Agrobacterium-mediated transfer of T-DNA constructs containing telomere sequences. Blocks of Arabidopsis-like telomeric repeats were inserted into a binary vector suitable for stable transformation. After transfer of these constructs into immature embryos of diploid and tetraploid barley, chromosome truncation by T-DNA-induced de novo formation of telomeres could be confirmed by fluorescent in situ hybridisation, primer extension telomere repeat amplification and DNA gel blot analysis in regenerated plants. Telomere seeding connected to chromosome truncation was found in tetraploid plants only, indicating that genetic redundancy facilitates recovery of shortened chromosomes. Truncated chromosomes were transmissible in sexual reproduction, but were inherited at rates lower than expected according to Mendelian rules. [ABSTRACT FROM AUTHOR]

Diversity arrays technology (DArT) genomic libraries were developed from H. chilense accessions to support robust genotyping of this species and a novel crop comprising H. chilense genome (e.g., tritordeums). Over 11,000 DArT clones were obtained using two complexity reduction methods. A subset of 2,209 DArT markers was identified on the arrays containing these clones as polymorphic between parents and segregating in a population of 92 recombinant inbred lines (RIL) developed from the cross between H. chilense accessions H1 and H7. Using the segregation data a high-density map of 1,503 cM was constructed with average inter-bin density of 2.33 cM. A subset of DArT markers was also mapped physically using a set of wheat- H. chilense chromosome addition lines. It allowed the unambiguous assignment of linkage groups to chromosomes. Four segregation distortion regions (SDRs) were found on the chromosomes 2H, 3H and 5H in agreement with previous findings in barley. The new map improves the genome coverage of previous H. chilense maps. H. chilense-derived DArT markers will enable further genetic studies in ongoing projects on hybrid wheat, seed carotenoid content improvement or tritordeum breeding program. Besides, the genetic map reported here will be very useful as the basis to develop comparative genomics studies with barley and model species. [ABSTRACT FROM AUTHOR]

The process of vernalization is mainly controlled by two genes in winter barley ( Hordeum vulgare L.), VRNH1 and VRNH2. A recessive allele at VRNH1 and a dominant allele at VRNH2 must be present to induce a vernalization requirement. In addition, this process is usually associated with greater low-temperature tolerance. Spanish barleys originated in areas with mild winters and display a reduced vernalization requirement compared with standard winter cultivars. The objective of this study was to investigate the genetic origin of this reduced vernalization requirement and its effect on frost tolerance. We introgressed the regions of a typical Spanish barley line that carry VRNH1 and VRNH2 into a winter cultivar, Plaisant, using marker-assisted backcrossing. We present the results of a set of 12 lines introgressed with all four possible combinations of VRNH1 and VRNH2, which were evaluated for vernalization requirement and frost tolerance. The reduced vernalization requirement of the Spanish parent was confirmed, and was found to be due completely to the effect of the VRNH1 region. The backcross lines showed no decline in frost tolerance compared with that of the recurrent parent unless they carried an extra segment of chromosome 5H. This extra segment, a carryover of the backcross process, apparently contained the well-known frost tolerance quantitative trait locus Fr- H2. We demonstrate that it is possible to manipulate the vernalization requirement with only minor effects on frost tolerance. This finding opens the path to creating new types of barley cultivars that are better suited to specific environments, especially in a climate-change scenario. [ABSTRACT FROM AUTHOR]

We used gametocidal (Gc) chromosomes 2C and 3CSAT to dissect barley 2H added to common wheat. The Gc chromosome induces chromosomal breakage resulting in chromosomal aberrations in the progeny of the 2H addition line of common wheat carrying the monosomic Gc chromosome. We conducted in situ hybridization to select plants carrying structurally rearranged aberrant 2H chromosomes and characterized them by sequential C-banding and in situ hybridization. We established 66 dissection lines of common wheat carrying single aberrant 2H chromosomes. The aberrant 2H chromosomes were of either deletion or translocation or complicated structural change. Their breakpoints were distributed in the short arm (2HS), centromere (2HC) and the long arm (2HL) at a rough 2HS/2HC/2HL ratio of 2:1:2. We conducted PCR analysis of the 66 dissection lines using 115 EST markers specific to chromosome 2H. Based on the PCR result, we constructed a physical or cytological map of chromosome 2H that were divided into 34 regions separated by the breakpoints of the aberrant 2H chromosomes. Forty-seven markers were present in 2HS and 68 in 2HL. We compared the 2H cytological map with a previously reported 2H genetic map using 44 markers that were used in common to construct both maps. The order of markers in the distal region was the same on both maps but that in the proximal region was somewhat contradictory between the two maps. We found that the markers distributed rather evenly in the genetic map were actually concentrated in the distal regions of both arms as revealed by the cytological map. We also recognized an EST-marker or gene-rich region in the 2HL interstitial region slightly to the telomere. [ABSTRACT FROM AUTHOR]

Stem rust (Puccinia graminis f. sp. tritici; Pgt) is a devastating fungal disease of wheat and barley. Pgt race TTKSK (isolate Ug99) is a serious threat to these Triticeae grain crops because resistance is rare. In barley, the complex Rpg-TTKSK locus on chromosome 5H is presently the only known source of qualitative resistance to this aggressive Pgt race. Segregation for resistance observed on seedlings of the Q21861 6SM89010 (QSM) doubled-haploid (DH) population was found to be predominantly qualitative, with little of the remaining variance explained by loci other than Rpg-TTKSK. In contrast, analysis of adult QSM DH plants infected by field inoculum of Pgt race TTKSK in Njoro, Kenya, revealed several additional quantitative trait loci that contribute to resistance. To molecularly characterize these loci, Barley1 GeneChips were used to measure the expression of 22,792 genes in the QSM population after inoculation with Pgt race TTKSK or mock-inoculation. Comparison of expression Quantitative Trait Loci (eQTL) between treatments revealed an inoculation-dependent expression polymorphism implicating Actin depolymerizing factor3 (within the Rpg-TTKSK locus) as a candidate susceptibility gene. In parallel, we identified a chromosome 2H trans-eQTL hotspot that co-segregates with an enhancer of Rpg-TTKSK-mediated, adult plant resistance discovered through the Njoro field trials. Our genome-wide eQTL studies demonstrate that transcript accumulation of 25% of barley genes is altered following challenge by Pgt race TTKSK, but that few of these genes are regulated by the qualitative Rpg-TTKSK on chromosome 5H. It is instead the chromosome 2H trans-eQTL hotspot that orchestrates the largest inoculation-specific responses, where enhanced resistance is associated with transcriptional suppression of hundreds of genes scattered throughout the genome. Hence, the present study associates the early suppression of genes expressed in this host-pathogen interaction with enhancement of R-gene mediated resistance. [ABSTRACT FROM AUTHOR]

A QTL analysis was performed to determine the inheritance of flowering time in barley, using a set of recombinant inbred lines developed from a winter-type × spring-type cross. Two photoperiod responsive loci, Ppd-H1 and Ppd-H2, were detected on chromosome arms 2HS and 1HL respectively. Segregation for eam8 (mapping to the terminus of chromosome arm 1HL) and Eam5 (close to Sgh2 on chromosome arm 5HL) was also observed. These latter two genes functioned under 12 h to 24 h photoperiods. In addition, eps2S and eps7S, known to lie on chromosome arms 2HS and 7HS respectively, were detected. A new QTL for flowering time, qDHE.ak-1HS, was mapped 23 cM from the terminus of chromosome 1HS, and appears to be expressed under extremely short day lengths. [ABSTRACT FROM AUTHOR]

Single nucleotide polymorphism (SNP) genotyping is useful for assessing genetic variation in germplasm collections, genetic map development and detection of alien chromosome substitutions. In this study, a diversity analysis using 1,301 SNPs on a set of 37 barley accessions was conducted. This analysis showed a high polymorphism rate between the malting barley cultivar ‘Haruna Nijo’ and the food barley cultivar ‘Akashinriki’. Haruna Nijo and Akashinriki are donors of the barley expressed sequence tag (EST) collections. A doubled haploid (DH) population derived from the cross between Haruna Nijo and Akashinriki was genotyped with 1,448 SNPs. Of these 1,448 SNPs, 734 were polymorphic and distributed on barley linkage groups (chromosomes) as follows: 1H (86), 2H (125), 3H (120), 4H (100), 5H (127), 6H (88) and 7H (88). By using cMAP, we integrated the SNP markers across high-density maps. The SNPs were also used to genotype 98 BC3F4 recombinant chromosome substitution lines (RCSLs) developed from the same cross (Haruna Nijo/Akashinriki). These data were used to create graphical genotypes for each line and thus estimate the location, extent and total number of introgressions from Akashinriki in the Haruna Nijo background. The 35 selected RCSLs sample most of the Akashinriki food barley genome, with only a few missing segments. These resources bring new alleles into the malting barley gene pool from food barley. [ABSTRACT FROM AUTHOR]

breeding objective for the malting barley industry is to produce lines with softer, plumper grain containing moderate protein content (9-12%) as they are more likely to imbibe water readily and contain more starch per grain, which in turn produces higher levels of malt extract. In a malting barley mapping population, 'Arapiles' × 'Franklin', the most significant and robust quantitative trait locus (QTL) for endosperm hardness was observed on the short arm of chromosome 1H, across three environments over two growing seasons. This accounted for 22.6% (Horsham 2000), 26.8% (Esperance 2001), and 12.0% (Tarranyurk 2001) of the genetic variance and significantly increased endosperm hardness by 2.06-3.03 SKCS hardness units. Interestingly, Arapiles and Franklin do not vary in Ha locus alleles. Therefore, this region, near the centromere on chromosome 1H, may be of great importance when aiming to manipulate endosperm hardness and malting quality. Interestingly, this region, close to the centromere on chromosome 1H, in our study, aligns with the region of the genome that includes the HvCslF9 and the HvGlb1 genes. Potentially, one or both of these genes could be considered to be candidate genes that influence endosperm hardness in the barley grain. Additional QTLs for endosperm hardness were detected on chromosomes 2H, 3H, 6H and 7H, confirming that the hardness trait in barley is complex and multigenic, similar to many malting quality traits of interest. [ABSTRACT FROM AUTHOR]

We have previously shown that linkage disequilibrium (LD) in the elite cultivated barley (Hordeum vulgare) gene pool extends, on average, for <1-5 cM. Based on this information, we have developed a platform for whole genome association studies that comprises a collection of elite lines that we have characterized at 3060 genome-wide single nucleotide polymorphism (SNP) marker loci. Interrogating this data set shows that significant population substructure is present within the elite gene pool and that diversity and LD vary considerably across each of the seven barley chromosomes. However, we also show that a subpopulation comprised of only the two-rowed spring germplasm is less structured and well suited to whole genome association studies without the need for extensive statistical intervention to account for structure. At the current marker density, the two-rowed spring population is suited for fine mapping simple traits that are located outside of the genetic centromeres with a resolution that is sufficient for candidate gene identification by exploiting conservation of synteny with fully sequenced model genomes and the emerging barley physical map. [ABSTRACT FROM AUTHOR]

Distal localisation of chiasmata is common to many cereals and grasses, which consigns many genes of the complement to recombination backwaters. Releasing this potential untapped genetic variation for use in advanced breeding programmes is an ambitious and technically demanding challenge, necessitating controlled shifts in the distribution of crossover events. As part of a collaborative programme to manipulate recombination in barley, we are developing a robust and reliable molecular cytogenetic assay for recombination in this species, which will be used to gauge the success of our forward and reverse genetic interventions. Single-locus bacterial artificial chromosome clones and rDNA probes identify the 7 somatic chromosomes of the complement. Meiocytes at pachytene of meiosis were embedded in polyacrylamide and hybridised in situ with centromere and telomere probes, followed by immunolocalisation of the synaptonemal complex-associated protein Asy1 which highlights the bivalents’ axes. Optical sectioning, deconvolution and image analysis of the z-stacks of the nuclei allowed the disentanglement of each bivalent and the construction of an accurate meiotic ideogram. The landing of single-locus bacterial artificial chromosomes and the detection of late recombination proteins will complete the assay and provide a means of discerning subtle changes in recombination in this species. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

We used two gametocidal (Gc) chromosomes 2C and 3CSAT to dissect barley chromosome 4H added to common wheat. The Gc chromosome induced chromosomal structural rearrangements in the progeny of the 4H addition line of common wheat carrying the monosomic Gc chromosome. We conducted in situ hybridization to select plants carrying rearranged 4H chromosomes and characterized the rearranged chromosomes by sequential C-banding and in situ hybridization. We established 60 dissection lines of common wheat carrying single rearranged 4H chromosomes. The rearranged 4H chromosomes had either a deletion or a translocation or a complicated structural change. The breakpoints were distributed in the short arm, centromere and the long arm at a rough ratio of 2:2:1. We conducted PCR analysis using the dissection lines and 93 EST markers specific to chromosome 4H. Based on the PCR result, we constructed a cytological map of chromosome 4H with 18 regions separated by the breakpoints of the rearranged chromosomes. Thirty-seven markers were present in the short arm and 56 in the long arm, and about 70% of the markers were present in no more than the distal 25.6% and 43.1% regions of the short and long arms, respectively. It is noteworthy that nine of the short-arm markers and 13 of the long-arm markers existed in the small subtelomeric regions at both ends characterized by the HvT01 sequences. We reconstructed a genetic map using 38 of the 93 markers that was used to construct the cytological map of chromosome 4H. The order of the markers on the genetic map was almost the same as that on the cytological map. On the genetic map, no markers were available in the pericentromeric region, but on the cytological map, 14 markers were present in the proximal region, and one of the markers was in the centromeric region of the short arm. [ABSTRACT FROM AUTHOR]

We previously showed that H. secalinum and H. capense are allotetraploids carrying the Xa genome of H. marinum and the I genome of an unidentified diploid species. In this study, intraspecific variation in each tetraploid species was investigated with regard to intergenomic translocations and chromosomal distribution of rDNA sites. Genomic in situ hybridization revealed that three H. secalinum accessions examined did not carry intergenomic translocations, but that two of three H. capsense accessions analyzed carried a pair of intergenomic translocations. Multicolour fluorescence in situ hybridization showed that H. secalinum included two types of rDNA pattern differing in the presence or absence of an extra 5S rDNA site in a submetacentric chromosome pair of the Xa-genome origin. The extra 5S rDNA site was found in all H. capense accessions examined. This 5S rDNA site is characteristic of H. marinum ssp. gussoneanum, but is absent in ssp. marinum. Polymorphisms in the 5S rDNA site infer that H. secalinum included two types, one having ssp. gussoneanum 2x and the other having ssp. marinum, as the Xa-genome donor. We conclude that H. capense originated from a limited number of H. secalinum accessions introduced probably through migrating birds to South Africa. [ABSTRACT FROM AUTHOR]

The lateral spikelets of two-rowed barley are reduced in size and sterile, but in six-rowed barley all three spikelets are fully fertile. The trait is largely controlled by alleles at the vrsl locus on chromosome arm 2HL, as modified by the allele present at the / locus on chromosome arm 4HS. Molecular markers were developed to saturate the 4HS region by exploiting expressed sequence-tags, either previously mapped in barley to this region, or present in the syntenic region of rice chromosome 3. Collinearity between rice and barley was strong in the 4.8cM interval BJ468164-AV933435 and the 10cM interval AV942364-BJ455560. A major QTL for lateral spikelet fertility (the I locus) explained 44% of phenotypic variance, and was located in the interval CB873567-BJ4739I6. The genotyping of near-isogenic lines for I placed the locus in a region be-tween CB873567 and EBmac635, and therefore the most likely position of the I locus was proximal to CB873567 in a 5.3 cM interval between CB873567-BJ473916. [ABSTRACT FROM AUTHOR]

Chromosome 1H (approximately 622 Mb) of barley (Hordeum vulgare) was isolated by flow sorting and shotgun sequenced by GSFLX pyrosequencing to 1.3-fold coverage. Fluorescence in situ hybridization and stringent sequence comparison against genetically mapped barley genes revealed 95% purity of the sorted chromosome 1H fraction. Sequence comparison against the reference genomes of rice (Oryza sativa) and sorghum (Sorghum bicolor) and against wheat (Triticum aestivum) and barley expressed sequence tag datasets led to the estimation of 4,600 to 5,800 genes on chromosome 1H, and 38,000 to 48,000 genes in the whole barley genome. Conserved gene content between chromosome 1H and known syntenic regions of rice chromosomes 5 and 10, and of sorghum chromosomes 1 and 9 was detected on a per gene resolution. Informed by the syntenic relationships between the two reference genomes, genic barley sequence reads were integrated and ordered to deduce a virtual gene map of barley chromosome 1H. We demonstrate that synteny-based analysis of low-pass shotgun sequenced flow-sorted Triticeae chromosomes can deliver linearly ordered high-resolution gene inventories of individual chromosomes, which complement extensive Triticeae expressed sequence tag datasets. Thus, integration of genomic, transcriptomic, and synteny-derived information represents a major step toward developing reference sequences of chromosomes and complete genomes of the most important plant tribe for mankind. [ABSTRACT FROM AUTHOR]

Chromosome 1H (approximately 622 Mb) of barley (Hordeum vulgare) was isolated by flow sorting and shotgun sequenced by GSFLX pyrosequencing to 1.3-fold coverage. Fluorescence in situ hybridization and stringent sequence comparison against genetically mapped barley genes revealed 95% purity of the sorted chromosome 1H fraction. Sequence comparison against the reference genomes of rice (Oryza sativa) and sorghum (Sorghum bicolor) and against wheat (Triticum aestivum) and barley expressed sequence tag datasets led to the estimation of 4,600 to 5,800 genes on chromosome 1H, and 38,000 to 48,000 genes in the whole barley genome. Conserved gene content between chromosome 1H and known syntenic regions of rice chromosomes 5 and 10, and of sorghum chromosomes 1 and 9 was detected on a per gene resolution. Informed by the syntenic relationships between the two reference genomes, genic barley sequence reads were integrated and ordered to deduce a virtual gene map of barley chromosome 1H. We demonstrate that synteny-based analysis of low-pass shotgun sequenced flow-sorted Triticeae chromosomes can deliver linearly ordered high-resolution gene inventories of individual chromosomes, which complement extensive Triticeae expressed sequence tag datasets. Thus, integration of genomic, transcriptomic, and synteny-derived information represents a major step toward developing reference sequences of chromosomes and complete genomes of the most important plant tribe for mankind. [ABSTRACT FROM AUTHOR]

Barley yellow dwarf virus (BYDV) causes high yield losses in most of the major cereal crops worldwide. A source of very effective resistance was detected within the tetraploid wild species of Hordeum bulbosum. Interspecific crosses between a resistant H. bulbosum accession and H. vulgare cv. ‘Igri’ were performed to transfer this resistance into cultivated barley. Backcrosses to H. vulgare resulted in offspring which carried a single subterminal introgression of H. bulbosum chromatin on barley chromosome 3HL and proved to be fully resistant to BYDV-PAV, as inferred by ELISA values of zero or close to zero and lack of BYDV symptoms. Genetic analysis indicated a dominant inheritance of the BYDV-PAV resistance factor, which we propose to denote Ryd4 Hb . The identity and effect of Ryd4 Hb are discussed in relation to other known genes for BYDV resistance or tolerance, as well as the relevance of this gene for resistance breeding in barley. [ABSTRACT FROM AUTHOR]

An original method has been established for the identification of novel alleles of eukaryotic translation initiation factor 4E ( eIF4E) gene, which is required for resistance to agronomically important bymoviruses, in barley germplasm. This method involves scanning for sequence variations in cDNA-derived PCR amplicons using High-resolution melting (HRM) followed by direct Sanger sequencing of only those amplicons which were predicted to carry nucleotide changes. HRM is a simple, cost-effective, rapid and high-throughput assay, which so far has only been widely used in clinical pathology for molecular diagnostic of diseases and patient genotyping. Application of HRM allowed significant reduction in the amount of expensive Sanger sequencing required for allele mining in plants. The method described here involved an investigation of total cDNA rather than genomic DNA, thus permitting the analyses of shorter (up to 300-bp) and fewer overlapping amplicons to cover the coding sequence. This strategy further reduced the allele mining costs. The sensitivity and accuracy of HRM for predicting genotypes carrying a wide range of nucleotide polymorphisms in eIF4E approached 100%. Results of the current study are promising and suggest that this method could also potentially be applied to the discovery of superior alleles controlling other important traits in barley as well in other model and crop plant species. [ABSTRACT FROM AUTHOR]

A major gene-rich region on the end of the long arm of Triticeae group 2 chromosomes exhibits high recombination frequencies, making it an attractive region for positional cloning. Traits known to be controlled by this region include chasmogamy/cleistogamy, frost tolerance at flowering, grain yield, head architecture, and resistance to Fusarium head blight and rusts. To assist these cloning efforts, we constructed detailed genetic maps of barley chromosome 2H, including 61 polymerase chain reaction markers. Colinearity with rice occurred in eight distinct blocks, including five blocks in the terminal gene-rich region. Alignment of rice sequences from the junctions of colinear chromosome segments provided no evidence for the involvement of long (>2.5 kb) inverted repeats in generating inversions. However, reuse of some junction sequences in two or three separate evolutionary breakage/fusion events was implicated, suggesting the presence of fragile sites. Sequencing across 91 gene fragments totaling 107 kb from four barley genotypes revealed the highest single nucleotide substitution and insertion–deletion polymorphism levels in the terminal regions of the chromosome arms. The maps will assist in the isolation of genes from the chromosome 2L gene-rich region in barley and wheat by providing markers and accelerating the identification of the corresponding points in the rice genome sequence. [ABSTRACT FROM AUTHOR]

Background: Flow cytometry facilitates sorting of single chromosomes and chromosome arms which can be used for targeted genome analysis. However, the recovery of microgram amounts of DNA needed for some assays requires sorting of millions of chromosomes which is laborious and time consuming. Yet, many genomic applications such as development of genetic maps or physical mapping do not require large DNA fragments. In such cases time-consuming de novo sorting can be minimized by utilizing whole-genome amplification. Results: Here we report a protocol optimized in barley including amplification of DNA from only ten thousand chromosomes, which can be isolated in less than one hour. Flow-sorted chromosomes were treated with proteinase K and amplified using Phi29 multiple displacement amplification (MDA). Overnight amplification in a 20-microlitre reaction produced 3.7 - 5.7 micrograms DNA with a majority of products between 5 and 30 kb. To determine the purity of sorted fractions and potential amplification bias we used quantitative PCR for specific genes on each chromosome. To extend the analysis to a whole genome level we performed an oligonucleotide pool assay (OPA) for interrogation of 1524 loci, of which 1153 loci had known genetic map positions. Analysis of unamplified genomic DNA of barley cv. Akcent using this OPA resulted in 1426 markers with present calls. Comparison with three replicates of amplified genomic DNA revealed >99% concordance. DNA samples from amplified chromosome 1H and a fraction containing chromosomes 2H - 7H were examined. In addition to loci with known map positions, 349 loci with unknown map positions were included. Based on this analysis 40 new loci were mapped to 1H. Conclusion: The results indicate a significant potential of using this approach for physical mapping. Moreover, the study showed that multiple displacement amplification of flow-sorted chromosomes is highly efficient and representative which considerably expands the potential of chromosome flow sorting in plant genomics. [ABSTRACT FROM AUTHOR]

We studied some features of the development of self-fertile 42-chromosome lines on the base of self-pollination progeny of 46-chromosome plants obtained by backcrossing of barley-wheat hybrids Hordeum marinum subsp. gussoneanum Hudson (= H. geniculatum All.) (2 n = 28) × Triticum aestivum L. (2 n = 42). The stabilization of karyotypes, resulting in 42-chromosome plants of the wheat type was generally completed by generation BC1F10. The plants of all self-pollination progenies, including BC1F10, showed some phenotypic traits characteristic of wild barley. Plants of BC1F10 with the chromosome sets 2 n = 42 and 2 n = 42 + t were analyzed by RAPD with a set of 115 primers. Fragments of the wild barley genome were detected in RAPD patterns with 19 primers. Cross-hybridization confirmed that these fragments belonged to the wild barley genome. We raised four phenotypically different 42-chromosome lines from grains obtained from plants of generation BC1F10, and these lines proved to be cytogenetically stable and self-fertile when grown in the field. [ABSTRACT FROM AUTHOR]

A range of single tagged site (STS), simple sequence repeat (SSR), and sequence-characterized amplified region (SCAR) markers were screened for their utility in detecting Hordeum vulgare and H. chilense chromosomes in a wheat background. PCR conditions were optimized for specific amplification of the targeted sequences and to avoid cross-species amplification. Two H. vulgare derived STSs, six H. vulgare derived SSRs, and nine H. chilense derived SCARs were usable for the detection of five H. vulgare and three H. chilense chromosomes by direct ethidium bromide staining of the PCR products in test tubes, avoiding the more costly and time-consuming DNA electrophoresis step. The practical application of the method is illustrated by the identification of a monotelosomic substitution of H. vulgare chromosome 6HS in tritordeum and a monosomic addition of H. chilense chromosome 6H[sup ch] in durum wheat.Key words: GISH, Hordeum chilense, Hordeum vulgare, marker-assisted selection, SSR, Tritordeum.Un ensemble de marquers de type STS (« single-tagged-site »), microsatellite (SSR) et SCAR (« sequence-characterized amplified region ») ont été examinés quant à leur utilité potentielle pour la détection de chromosomes du Hordeum vulgare et du H. chilense dans un fond génétique du blé. Les conditions PCR ont été optimisées pour l'amplification spécifique des séquences ciblées et pour éviter l'amplification croisée entre espèces. Deux marqueurs STS dérivés du H. vulgare, six microsatellites dérivés du H. vulgare et neuf SCAR dérivés du H. chilense permettaient de détecter cinq chromosomes du H. vulgare et trois chromosomes du H. chilense par simple détection des amplicons au bromure d'éthidium dans des tubes réactionnels, évitant ainsi l'étape plus longue et coûteuse de l'électrophorèse. L'intérêt pratique de cette méthode est illustré via l'identification d'une substitution monotélosomique du chromosome 6HS du H. vulgare chez une lignée issue d'un croisement blé-orge (tritordeum) ainsi que par l'identification d'une addition monosomique du chromosome 6H[sup ch] du H. chilense chez le blé durum.Mots clés : GISH, Hordeum chilense, Hordeum vulgare, sélection assistée, microsatellite, Tritordeum[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

To provide improved access to the wealth of resources and genomic information that is presently being developed for rice a set of 88 rice expressed sequence tags (ESTs) previously mapped on rice chromosome 1 in the cross 'Nipponbare' × 'Kasalath' was used for comparative mapping in a cross of the barley cultivars 'Igri' and 'Franka'. As expected, most (89%) of the clones gave distinct banding patterns in barley of which about one-third was polymorphic between 'Igri' and 'Franka'. These polymorphisms were mapped, and most of these (56%) confirmed that rice chromosome 1 and barley chromosome 3H are syntenous. All single-copy markers identified conserved collinear positions, while markers with multiple copies did so in a few cases only. The markers that were not fitting in the collinear order were distributed randomly across the barley genome. The comparative maps of barley chromosome 3H and rice chromosome 1 comprise in total 26 common markers covering more than 95% of the genetic length of both chromosomes. A 30-fold reduction of recombination is seen around the barley centromere, and synteny may be interrupted in this region. However, the good overall synteny on a mesoscale (1–10 cM) justifies the use of rice as a platform for map-based cloning in barley.Key words: Oryza sativa, Hordeum vulgare, RFLP, synteny, comparative mapping.Afin d'améliorer l'accès aux importantes ressources et à l'abondance d'information génomique qui sont en développement chez le riz, un jeu de 88 EST du riz a été employé pour réaliser de la cartographie comparée chez l'orge sur une population issue du croisement 'Igri' × 'Franka'. Ces EST avaient déjà été localisés sur le chromosome 1 du riz suite à des travaux de cartographie génétique sur le croisement 'Nipponbare' × 'Kasalath'. Tel qu'attendu, la plupart (89 %) des clones ont produit des bandes distinctes chez l'orge et environ le tiers de ces sondes se sont avérées polymorphes entre 'Igri' et 'Franka'. Ces polymorphismes ont été cartographiés. Une majorité de ceux-ci (56 %) ont confirmé que les chromosomes 1 du riz et 3H de l'orge sont syntènes. Tous les marqueurs à simple copie identifiés ont montré une conservation de leur position tandis que les marqueurs à copies multiples ne l'ont fait que rarement. Les marqueurs ne se conformant pas à la colinéarité étaient distribués de façon aléatoire dans le génome de l'orge. Les cartes génétiques comparées des chromosomes 3H de l'orge et 1 du riz comptent 26 marqueurs communs s'échelonnant sur plus de 95 % de la longueur totale de ces deux chromosomes. Une réduction du taux de recombinaison d'environ 30 fois a été observée autour du centromère de l'orge et la synténie pourrait être interrompue dans cette région. Malgré tout, la bonne synténie globale à une échelle moyenne (1–10 cM) justifie l'emploi du riz en tant que plate-forme pour le clonage positionnel chez l'orge.Mots clés : Oryza sativa, Hordeum vulgare, RFLP, synténie, cartographie comparée.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Barley has several important traits that might be used in the genetic improvement of wheat. For this report, we have produced wheat-barley recombinants involving barley chromosomes 4 (4H) and 7 (5H). Wheat-barley disomic addition lines were crossed with 'Chinese Spring' wheat carrying the ph1b mutation to promote homoeologous pairing. Selection was performed using polymerase chain reaction (PCR) markers to identify lines with the barley chromosome in the ph1b background. These lines were self pollinated, and recombinants were identified using sequence-tagged-site (STS) primer sets that allowed differentiation between barley and wheat chromosomes. Several recombinant lines were isolated that involved different STS-PCR markers. Recombination was confirmed by allowing the lines to self pollinate and rescreening the progeny via STS-PCR. Progeny testing confirmed 9 recombinants involving barley chromosome 4 (4H) and 11 recombinants involving barley chromosome 7 (5H). Some recombinants were observed cytologically to eliminate the possibility of broken chromosomes. Since transmission of the recombinant chromosomes was lower than expected and since seed set was reduced in recombinant lines, the utility of producing recombinants with this method is uncertain.Key words: introgression, sequence-tagged-site, recombination.L'orge possède plusieurs caractères importants qui pourraient être utiles en amélioration génétique du blé. Les auteurs rapportent ici la production de recombinants blé-orge impliquant les chromosomes 4 (4H) et 7 (5H) de l'orge. Des lignées d'addition disomiques blé-orge ont été croisées avec le blé 'Chinese Spring', lequel possède la mutation ph1b qui a pour effet de promouvoir l'appariement homéologue. Une sélection a été effectuée à l'aide de marqueurs PCR (réaction de polymérisation en chaîne) afin d'identifier des lignées présentant un chromosome d'orge dans une lignée de génotype ph1b. Ces lignées ont été autofécondées et les recombinants ont été identifiés à l'aide de marqueurs STS (séquence ciblée) qui permettaient de différencier les chromosomes du blé et de l'orge. Plusieurs lignées recombinantes ont été identifiées à l'aide de différents marqueurs STS. La recombinaison a été confirmée en laissant s'autoféconder ces lignées et en examinant à nouveau la progéniture par PCR. Ces tests ont permis de confirmer que neuf lignées recombinantes impliquaient le chromosome 4 (4H) et onze lignées le chromosome 7 (5H) de l'orge. Certains recombinants ont été analysés par examen cytologique afin d'éliminer la possibilité de chromosomes cassés. Puisque la transmission des chromosomes recombinants était plus faible qu'attendue et que la fécondité était réduite chez toutes les lignées recombinantes, l'utilité de produire ainsi des recombinants est incertaine.Mots clés : introgression, séquence ciblée (STS), recombinaison.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Describes a technique for the physical mapping of barley chromosomes using microdissected translocation chromosomes for PCR with sequence-tagged site primers. Cytogenetically integrated physical restriction fragment length polymorphism maps for seven barley chromosomes: Comparison of mapping accuracy to the deletion-based ladder maps of wheat.

Segregation distortion is a common phenomenon among anther-culture-derived plants and it has been suggested that the distorted areas may contain genes affecting survival in anther-culture. Segregation of 111 markers was checked in an androgenetic barley (Hordeum vulgare L.) progeny and a linkage map was constructed. Thirty one progeny lines were tested for their anther-culture ability and associations between molecular markers and anther-culture traits were established. Two regions on chromosomes 2H and 4H were associated with anther response, three on 2H (two areas) and 3H with plant regeneration rate, and one on 4H with spontaneous diploidization. The chromosomal regions controlling anther-culture response and the regions where distorted segregation was found were not always the same. [ABSTRACT FROM AUTHOR]

Adult plant resistance against plant pathogens is of interest as a means to achieve durable resistance. Prior to this research, the barley lines CLE210 (from Uruguay) and Denar (from the Czech Republic) had been reported to exhibit adult-plant resistance against powdery mildew. Here, populations of doubled haploid lines from crosses of these lines with the susceptible cultivar Baudin were evaluated for powdery mildew resistance in field experiments. Using linkage maps constructed from genotyping-by-sequencing (GBS) data, it was determined that differences in resistance were largely attributable to a region on the long arm of chromosome 5H (5HL). Therefore, KASP™ assays were developed based on GBS tag sequences mapped on that chromosome, providing more reliable genetic maps. In each population, a large-effect QTL was mapped on 5HL. As no sequence variation was detected between CLE210 and Denar in this region of 5HL, the two sources of resistance may be identical by descent in the QTL region and carry the same resistance gene. Marker assays from the QTL region were evaluated on a panel of barley lines, providing information that breeders could use to select assays for use in marker-assisted selection. [ABSTRACT FROM AUTHOR]