Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany.
BMC Genomics. 2011 Jan 19;12:48. doi: 10.1186/1471-2164-12-48.
The bumblebee Bombus terrestris is an ecologically and economically important pollinator and has become an important biological model system. To study fundamental evolutionary questions at the genomic level, a high resolution genetic linkage map is an essential tool for analyses ranging from quantitative trait loci (QTL) mapping to genome assembly and comparative genomics. We here present a saturated linkage map and match it with the Apis mellifera genome using homologous markers. This genome-wide comparison allows insights into structural conservations and rearrangements and thus the evolution on a chromosomal level.
The high density linkage map covers ~ 93% of the B. terrestris genome on 18 linkage groups (LGs) and has a length of 2'047 cM with an average marker distance of 4.02 cM. Based on a genome size of ~ 430 Mb, the recombination rate estimate is 4.76 cM/Mb. Sequence homologies of 242 homologous markers allowed to match 15 B. terrestris with A. mellifera LGs, five of them as composites. Comparing marker orders between both genomes we detect over 14% of the genome to be organized in synteny and 21% in rearranged blocks on the same homologous LG.
This study demonstrates that, despite the very high recombination rates of both A. mellifera and B. terrestris and a long divergence time of about 100 million years, the genomes' genetic architecture is highly conserved. This reflects a slow genome evolution in these bees. We show that data on genome organization and conserved molecular markers can be used as a powerful tool for comparative genomics and evolutionary studies, opening up new avenues of research in the Apidae.
熊蜂 Bombus terrestris 是一种具有重要生态和经济意义的传粉媒介，已成为重要的生物模式系统。为了在基因组水平上研究基本的进化问题，高分辨率遗传连锁图谱是从数量性状位点（QTL）作图到基因组组装和比较基因组学分析的重要工具。我们在这里呈现了一张饱和的连锁图谱，并使用同源标记将其与 Apis mellifera 基因组进行匹配。这种全基因组比较可以深入了解结构保守性和重排，从而了解染色体水平上的进化。
高密度连锁图谱覆盖了 18 条连锁群（LG）上的93%的 B. terrestris 基因组，长度为 2'047 cM，平均标记距离为 4.02 cM。基于430 Mb 的基因组大小，重组率估计为 4.76 cM/Mb。242 个同源标记的序列同源性允许将 15 个 B. terrestris 与 A. mellifera LG 进行匹配，其中 5 个为复合 LG。比较两个基因组之间的标记顺序，我们检测到超过 14%的基因组在同一条同源 LG 上以同线性组织，21%以重排块的形式组织。
这项研究表明，尽管 A. mellifera 和 B. terrestris 的重组率非常高，而且分化时间长达约 1 亿年，但基因组的遗传结构高度保守。这反映了这些蜜蜂的基因组进化缓慢。我们表明，基因组组织和保守分子标记的数据可作为比较基因组学和进化研究的有力工具，为 Apidae 的研究开辟了新途径。
