Sequencing of 15 622 gene-bearing BACs clarifies the gene-dense regions of the barley genome.

Muñoz-Amatriaín, M., Lonardi, S., Luo, M., Madishetty, K., Svensson, J.T., Moscou, M.J., Wanamaker, S., Jiang, T., Kleinhofs, A., Muehlbauer, G., Wise, R.P., Stein, N., Ma, Y., Rodriguez, E., Kudrna, D., Bhat, P.R., Chao, S., Condamine, P., Heinen, S., Resnik, J., Wing, R., Witt, H.N., Alpert, M., Beccuti, M., Bozdag, S., Cordero, F., Mirebrahim, H., Ounit, R., Wu, Y., You, F.M., Zheng, J., Šimková, H., Doležel, J., Grimwood, J., Schmutz, J., Duma, D., Altschmied, L., Blake, T., Bregitzer, P., Cooper, L., Dilbirligi, M., Falk, A., Feiz, L., Graner, A., Gustafsson, P., Haygarth, P.M., Lemaux, P.G., Mammadov, J., and Close, T.J. (2015). "Sequencing of 15 622 gene-bearing BACs clarifies the gene-dense regions of the barley genome.", The Plant Journal, 84(1), pp. 216-227. doi : 10.1111/tpj.12959  Access to full text

Abstract

Barley (Hordeum vulgare L.) possesses a large and highly repetitive genome of 5.1 Gb that has hindered the development of a complete sequence. In 2012, the International Barley Sequencing Consortium released a resource integrating whole-genome shotgun sequences with a physical and genetic framework. However, because only 6278 bacterial artificial chromosome (BACs) in the physical map were sequenced, fine structure was limited. To gain access to the gene-containing portion of the barley genome at high resolution, we identified and sequenced 15 622 BACs representing the minimal tiling path of 72 052 physical-mapped gene-bearing BACs. This generated ~1.7 Gb of genomic sequence containing an estimated 2/3 of all Morex barley genes. Exploration of these sequenced BACs revealed that although distal ends of chromosomes contain most of the gene-enriched BACs and are characterized by high recombination rates, there are also gene-dense regions with suppressed recombination. We made use of published map-anchored sequence data from Aegilops tauschii to develop a synteny viewer between barley and the ancestor of the wheat D-genome. Except for some notable inversions, there is a high level of collinearity between the two species. The software HarvEST:Barley provides facile access to BAC sequences and their annotations, along with the barley–Ae. tauschii synteny viewer. These BAC sequences constitute a resource to improve the efficiency of marker development, map-based cloning, and comparative genomics in barley and related crops. Additional knowledge about regions of the barley genome that are gene-dense but low recombination is particularly relevant.

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