Authors

The International Barley Genome Sequencing Consortium; Principal investigators, Mayer KF, Waugh R, Langridge P, Close TJ, Wise RP, Graner A, Matsumoto T, Sato K, Schulman A, Muehlbauer GJ, Stein N; Physical map construction and direct anchoring, Ariyadasa R, Schulte D, Poursarebani N, Zhou R, Steuernagel B, Mascher M, Scholz U, Shi B, Langridge P, Madishetty K, Svensson JT, Bhat P, Moscou M, Resnik J, Close TJ, Muehlbauer GJ, Hedley P, Liu H, Morris J, Waugh R, Frenkel Z, Korol A, Bergès H, Graner A, Stein N; Genomic sequencing and assembly, Steuernagel B, Scholz U, Taudien S, Felder M, Groth M, Platzer M, Stein N; BAC sequencing and assembly, Steuernagel B, Scholz U, Himmelbach A, Taudien S, Felder M, Platzer M, Lonardi S, Duma D, Alpert M, Cordero F, Beccuti M, Ciardo G, Ma Y, Wanamaker S, Close TJ, Stein N; BAC-end sequencing, Cattonaro F, Vendramin V, Scalabrin S, Radovic S, Wing R, Schulte D, Steuernagel B, Morgante M, Stein N, Waugh R; Integration of physical/genetic map and sequence resources, Nussbaumer T, Gundlach H, Martis M, Ariyadasa R, Poursarebani N, Steuernagel B, Scholz U, Wise RP, Poland J, Stein N, Mayer KF; Gene annotation, Spannagl M, Pfeifer M, Gundlach H, Mayer KF; Repetitive DNA analysis, Gundlach H, Moisy C, Tanskanen J, Scalabrin S, Zuccolo A, Vendramin V, Morgante M, Mayer KF, Schulman A; Transcriptome sequencing and analysis, Pfeifer M, Spannagl M, Hedley P, Morris J, Russell J, Druka A, Marshall D, Bayer M, Swarbreck D, Sampath D, Ayling S, Febrer M, Caccamo M, Matsumoto T, Tanaka T, Sato K, Wise RP, Close TJ, Wannamaker S, Muehlbauer GJ, Stein N, Mayer KF, Waugh R; Re-sequencing and diversity analysis, Steuernagel B, Schmutzer T, Mascher M, Scholz U, Taudien S, Platzer M, Sato K, Marshall D, Bayer M, Waugh R, Stein N; Writing and editing of the manuscript, Mayer KF, Waugh R, Brown JW, Schulman A, Langridge P, Platzer M, Fincher GB, Muehlbauer GJ, Sato K, Close TJ, Wise RP, Stein N.

Nature. 2012 Oct 17. doi: 10.1038/nature11543.

Abstract

Barley (Hordeum vulgare L.) is among the world's earliest domesticated and most important crop plants. It is diploid with a large haploid genome of 5.1 gigabases (Gb). Here we present an integrated and ordered physical, genetic and functional sequence resource that describes the barley gene-space in a structured whole-genome context. We developed a physical map of 4.98 Gb, with more than 3.90 Gb anchored to a high-resolution genetic map. Projecting a deep whole-genome shotgun assembly, complementary DNA and deep RNA sequence data onto this framework supports 79,379 transcript clusters, including 26,159 'high-confidence' genes with homology support from other plant genomes. Abundant alternative splicing, premature termination codons and novel transcriptionally active regions suggest that post-transcriptional processing forms an important regulatory layer. Survey sequences from diverse accessions reveal a landscape of extensive single-nucleotide variation. Our data provide a platform for both genome-assisted research and enabling contemporary crop improvement.

 Links :

http://www.ncbi.nlm.nih.gov/pubmed/23075845

http://www.international.inra.fr/press/barley_genome_sequenced

Authors

Bartos J, Vlcek C, Choulet F, Dzunková M, Cviková K, Safár J, Simková H, Paces J, Strnad H, Sourdille P, Bergès H, Cattonaro F, Feuillet C, Dolezel J.

BMC Plant Biol. (2012) Aug 30;12(1):155

Abstract

Background:
Polyploidization is considered one of the main mechanisms of plant genome evolution. The presence of multiple copies of the same gene reduces selection pressure and permits sub-functionalization and neo-functionalization leading to plant diversification, adaptation and speciation. In bread wheat, polyploidization and the prevalence of transposable elements resulted in massive gene duplication and movement. As a result, the number of genes which are non-collinear to genomes of related species seems markedly increased in wheat.

Results:
We used new-generation sequencing (NGS) to generate sequence of a Mb-sized region from wheat chromosome arm 3DS. Sequence assembly of 24 BAC clones resulted in two scaffolds of 1,264,820 and 333,768 bases. The sequence was annotated and compared to the homoeologous region on wheat chromosome 3B and orthologous loci of Brachypodium distachyon and rice. Among 39 coding sequences in the 3DS scaffolds, 32 have a homoeolog on chromosome 3B. In contrast, only fifteen and fourteen orthologs were identified in the corresponding regions in rice and Brachypodium, respectively. Interestingly, five pseudogenes were identified among the non-collinear coding sequences at the 3B locus, while none was found at the 3DS locus.

Conclusion:
Direct comparison of two Mb-sized regions of the B and D genomes of bread wheat revealed similar rates of non-collinear gene insertion in both genomes with a majority of gene duplications occurring before their divergence. Relatively low proportion of pseudogenes was identified among non-collinear coding sequences. Our data suggest that the pseudogenes did not originate from insertion of non-functional copies, but were formed later during the evolution of hexaploid wheat. Some evidence was found for gene erosion along the B genome locus.

Authors 

Mounet F, Moing A, Kowalczyk M, Rohrmann J, Petit J, Garcia V, Maucourt M, Yano K, Deborde C, Aoki K, Bergès H, Granell A, Fernie AR, Bellini C, Rothan C, Lemaire-Chamley M.

J Exp Bot. 2012 Aug;63(13):4901-17.

Abstract

The PIN-FORMED (PIN) auxin efflux transport protein family has been well characterized in the model plant Arabidopsis thaliana, where these proteins are crucial for auxin regulation of various aspects of plant development. Recent evidence indicates that PIN proteins may play a role in fruit set and early fruit development in tomato (Solanum lycopersicum), but functional analyses of PIN-silenced plants failed to corroborate this hypothesis. Here it is demonstrated that silencing specifically the tomato SlPIN4 gene, which is predominantly expressed in tomato flower bud and young developing fruit, leads to parthenocarpic fruits due to precocious fruit development before fertilization. This phenotype was associated with only slight modifications of auxin homeostasis at early stages of flower bud development and with minor alterations of ARF and Aux/IAA gene expression. However, microarray transcriptome analysis and large-scale quantitative RT-PCR profiling of transcription factors in developing flower bud and fruit highlighted differentially expressed regulatory genes, which are potential targets for auxin control of fruit set and development in tomato. In conclusion, this work provides clear evidence that the tomato PIN protein SlPIN4 plays a major role in auxin regulation of tomato fruit set, possibly by preventing precocious fruit development in the absence of pollination, and further gives new insights into the target genes involved in fruit set.

Authors

Dibari B, Murat F, Chosson A, Gautier V, Poncet C, Lecomte P, Mercier I, Bergès H, Pont C, Blanco A, Salse J.

BMC Genomics. 2012 Jun 6;13:221.

Abstract

Background :
Carotenoids are isoprenoid pigments, essential for photosynthesis and photoprotection in plants. The enzyme phytoene synthase (PSY) plays an essential role in mediating condensation of two geranylgeranyl diphosphate molecules, the first committed step in carotenogenesis. PSY are nuclear enzymes encoded by a small gene family consisting of three paralogous genes (PSY1-3) that have been widely characterized in rice, maize and sorghum.

Results :
In wheat, for which yellow pigment content is extremely important for flour colour, only PSY1 has been extensively studied because of its association with QTLs reported for yellow pigment whereas PSY2 has been partially characterized. Here, we report the isolation of bread wheat PSY3 genes from a Renan BAC library using Brachypodium as a model genome for the Triticeae to develop Conserved Orthologous Set markers prior to gene cloning and sequencing. Wheat PSY3 homoeologous genes were sequenced and annotated, unravelling their novel structure associated with intron-loss events and consequent exonic fusions. A wheat PSY3 promoter region was also investigated for the presence of cis-acting elements involved in the response to abscisic acid (ABA), since carotenoids also play an important role as precursors of signalling molecules devoted to plant development and biotic/abiotic stress responses. Expression of wheat PSYs in leaves and roots was investigated during ABA treatment to confirm the up-regulation of PSY3 during abiotic stress.

Conclusions :
We investigated the structural and functional determinisms of PSY genes in wheat. More generally, among eudicots and monocots, the PSY gene family was found to be associated with differences in gene copy numbers, allowing us to propose an evolutionary model for the entire PSY gene family in Grasses.

Authors

Goubet PM, Bergès H, Bellec A, Prat E, Helmstetter N, Mangenot S, Gallina S, Holl AC, Fobis-Loisy I, Vekemans X, Castric V.

PLoS Genet. 2012 Mar;8(3):e1002495.
PMID: 22457631

Abstract

Self-incompatibility has been considered by geneticists a model system for reproductive biology and balancing selection, but our understanding of the genetic basis and evolution of this molecular lock-and-key system has remained limited by the extreme level of sequence divergence among haplotypes, resulting in a lack of appropriate genomic sequences. In this study, we report and analyze the full sequence of eleven distinct haplotypes of the self-incompatibility locus (S-locus) in two closely related Arabidopsis species, obtained from individual BAC libraries. We use this extensive dataset to highlight sharply contrasted patterns of molecular evolution of each of the two genes controlling self-incompatibility themselves, as well as of the genomic region surrounding them. We find strong collinearity of the flanking regions among haplotypes on each side of the S-locus together with high levels of sequence similarity. In contrast, the S-locus region itself shows spectacularly deep gene genealogies, high variability in size and gene organization, as well as complete absence of sequence similarity in intergenic sequences and striking accumulation of transposable elements. Of particular interest, we demonstrate that dominant and recessive S-haplotypes experience sharply contrasted patterns of molecular evolution. Indeed, dominant haplotypes exhibit larger size and a much higher density of transposable elements, being matched only by that in the centromere. Overall, these properties highlight that the S-locus presents many striking similarities with other regions involved in the determination of mating-types, such as sex chromosomes in animals or in plants, or the mating-type locus in fungi and green algae.

Authors :

Lucas SJ, Simková H, Safár J, Jurman I, Cattonaro F, Vautrin S, Bellec A, Berges H, Doležel J, Budak H.

Funct Integr Genomics. 2011 Sep 3.

Abstract :

Bread wheat (Triticum aestivum L.) is one of the most important crops globally and a high priority for genetic improvement, but its large and complex genome has been seen as intractable to whole genome sequencing. Isolation of individual wheat chromosome arms has facilitated large-scale sequence analyses. However, so far there is no such survey of sequences from the A genome of wheat. Greater understanding of an A chromosome could facilitate wheat improvement and future sequencing of the entire genome. We have constructed BAC library from the long arm of T. aestivum chromosome 1A (1AL) and obtained BAC end sequences from 7,470 clones encompassing the arm. We obtained 13,445 (89.99%) useful sequences with a cumulative length of

7.57 Mb, representing 1.43% of 1AL and about 0.14% of the entire A genome. The GC content of the sequences was 44.7%, and 90% of the chromosome was estimated to comprise repeat sequences, while just over 1% encoded expressed genes. From the sequence data, we identified a large number of sites suitable for development of molecular markers

(362 SSR and 6,948 ISBP) which will have utility for mapping this chromosome and for marker assisted breeding. From 44 putative ISBP markers tested 23 (52.3%) were found to be useful. The BAC end sequence data also enabled the identification of genes and syntenic blocks specific to chromosome 1AL, suggesting regions of particular functional interest and targets for future research.