Surviving a Genome Collision: Genomic Signatures of Allopolyploidization in the Recent Crop Species Brassica napus
Surviving a Genome Collision: Genomic Signatures of Allopolyploidization in the Recent Crop Species Brassica napus
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DOI：
10.3835/plantgenome2017.02.0013
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发表时间：
2017-11-01
期刊：
影响因子：
4.2
通讯作者：
Snowdon, Rod J.
中科院分区：
文献类型：
--
作者：
Samans, Birgit;Chalhoub, Boulos;Snowdon, Rod J.
多倍化在作物植物进化中发挥了重要作用，导致人类选择的有利性状。在这里，我们描述了甘蓝型油菜基因组中的重组模式，一个最近的异源多倍体物种。广泛的节段缺失，重复，homeoprotein染色体交换被确定在不同的基因组序列从32个自然和20个合成加入，表明homeoprotein交换是一个主要的驱动程序后多倍化基因组多样化。基因组重排的断裂点富含微卫星序列，这些微卫星序列与减数分裂重组机制相互作用。无论是合成的还是天然的B。在甘蓝型油菜中，观察到一种亚基因组偏向，倾向于用较小的同源染色体A亚基因组片段替换来自C亚基因组的较大染色体片段，从而驱动多倍体化后基因组大小的减小。自然选择B。甘蓝型油菜倾向于涉及免疫、生殖和适应相关基因的片段缺失。缺失影响错配修复系统基因，这被认为是控制同源重组，也被认为是在选择。同源异源多倍体亚基因组之间的结构交换似乎是新的遗传多样性的一个主要来源。通过基因组重测序记录基因组碰撞的后果，可以深入了解伴随异源多倍体化的适应过程。
Polyploidization has played a major role in crop plant evolution, leading to advantageous traits that have been selected by humans. Here, we describe restructuring patterns in the genome of Brassica napus L., a recent allopolyploid species. Widespread segmental deletions, duplications, and homeologous chromosome exchanges were identified in diverse genome sequences from 32 natural and 20 synthetic accessions, indicating that homeologous exchanges are a major driver of postpolyploidization genome diversification. Breakpoints of genomic rearrangements are rich in microsatellite sequences that are known to interact with the meiotic recombination machinery. In both synthetic and natural B. napus, a subgenome bias was observed toward exchanges replacing larger chromosome segments from the C-subgenome by their smaller, homeologous A-subgenome segments, driving postpolyploidization genome size reduction. Selection in natural B. napus favored segmental deletions involving genes associated with immunity, reproduction, and adaptation. Deletions affecting mismatch repair system genes, which are assumed to control homeologous recombination, were also found to be under selection. Structural exchanges between homeologous subgenomes appear to be a major source of novel genetic diversity in de novo allopolyploids. Documenting the consequences of genomic collision by genomic resequencing gives insights into the adaptive processes accompanying allopolyploidization.