Genome-wide selection footprints and deleterious variations in young Asian allotetraploid rapeseed
Genome-wide selection footprints and deleterious variations in young Asian allotetraploid rapeseed
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DOI：
10.1111/pbi.13115
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发表时间：
2019-10-01
影响因子：
13.8
通讯作者：
Fan, Longjiang
中科院分区：
文献类型：
--
作者：
Zou, Jun;Mao, Lingfeng;Fan, Longjiang
甘蓝型油菜(Brassica napus，AACC，2n=38)是一种重要的世界性油料作物。然而，人们对该物种的种群进化、其主要遗传群体(如欧洲和亚洲油菜)之间的基因组差异以及历史上大规模的导入事件对这个年轻的四倍体的影响知之甚少。在本研究中，我们报道了亚洲油菜(B.napus)宁油7号及其四个祖先的基因组序列的从头组装，并将这些基因组与欧洲和亚洲不同品种的其他现有基因组数据进行了比较。我们的结果表明，亚洲油菜起源于欧洲油菜，但随后发生了显著的分化，杂交后基因组迅速分化，并进行了密集的地方选择育种。油菜的首次历史导入极大地扩大了亚洲油菜的等位基因库，但减少了亚洲油菜的有害变异。第二次欧洲油菜(油菜)双低性状的历史导入使亚洲油菜分为两个群体(双低和双高)，并伴随着双低群体遗传负荷的增加。这项研究展示了独特的基因组足迹和有害的SNP(单核苷酸多态)变异，以适应最近的种内和种间导入事件，并为理解年轻的异源多倍体作物的快速基因组进化提供了新的见解。
Brassica napus (AACC, 2n = 38) is an important oilseed crop grown worldwide. However, little is known about the population evolution of this species, the genomic difference between its major genetic groups, such as European and Asian rapeseed, and the impacts of historical large-scale introgression events on this young tetraploid. In this study, we reported the de novo assembly of the genome sequences of an Asian rapeseed (B. napus), Ningyou 7, and its four progenitors and compared these genomes with other available genomic data from diverse European and Asian cultivars. Our results showed that Asian rapeseed originally derived from European rapeseed but subsequently significantly diverged, with rapid genome differentiation after hybridization and intensive local selective breeding. The first historical introgression of B. rapa dramatically broadened the allelic pool but decreased the deleterious variations of Asian rapeseed. The second historical introgression of the double-low traits of European rapeseed (canola) has reshaped Asian rapeseed into two groups (double-low and double-high), accompanied by an increase in genetic load in the double-low group. This study demonstrates distinctive genomic footprints and deleterious SNP (single nucleotide polymorphism) variants for local adaptation by recent intra- and interspecies introgression events and provides novel insights for understanding the rapid genome evolution of a young allopolyploid crop.