Centre for Genome Research, University of Liverpool, Liverpool L69 7ZB, UK.
Nature. 2012 Nov 29;491(7426):705-10. doi: 10.1038/nature11650.
Bread wheat (Triticum aestivum) is a globally important crop, accounting for 20 per cent of the calories consumed by humans. Major efforts are underway worldwide to increase wheat production by extending genetic diversity and analysing key traits, and genomic resources can accelerate progress. But so far the very large size and polyploid complexity of the bread wheat genome have been substantial barriers to genome analysis. Here we report the sequencing of its large, 17-gigabase-pair, hexaploid genome using 454 pyrosequencing, and comparison of this with the sequences of diploid ancestral and progenitor genomes. We identified between 94,000 and 96,000 genes, and assigned two-thirds to the three component genomes (A, B and D) of hexaploid wheat. High-resolution synteny maps identified many small disruptions to conserved gene order. We show that the hexaploid genome is highly dynamic, with significant loss of gene family members on polyploidization and domestication, and an abundance of gene fragments. Several classes of genes involved in energy harvesting, metabolism and growth are among expanded gene families that could be associated with crop productivity. Our analyses, coupled with the identification of extensive genetic variation, provide a resource for accelerating gene discovery and improving this major crop.
面包小麦（Triticum aestivum）是全球重要的作物之一，占人类所消耗卡路里的 20%。全球范围内正在进行重大努力，通过扩展遗传多样性和分析关键特征来增加小麦产量，而基因组资源可以加速这一进程。但迄今为止，面包小麦基因组的巨大大小和多倍体复杂性一直是基因组分析的主要障碍。在这里，我们使用 454 焦磷酸测序技术报告了其 170 亿碱基对的六倍体基因组的测序，并将其与二倍体祖先和前体基因组的序列进行了比较。我们鉴定出了 94000 到 96000 个基因，并将其中三分之二分配给了六倍体小麦的三个组成基因组（A、B 和 D）。高分辨率的同线性图谱确定了许多对保守基因顺序的小破坏。我们表明，六倍体基因组具有高度的动态性，在多倍化和驯化过程中大量丧失了基因家族成员，并且存在大量的基因片段。参与能量收集、代谢和生长的几类基因是扩展的基因家族之一，它们可能与作物生产力有关。我们的分析，加上广泛的遗传变异的鉴定，为加速基因发现和改善这一主要作物提供了资源。
