Comparative Genomics of Apomictic Root-Knot Nematodes: Hybridization, Ploidy, and Dynamic Genome Change.
Comparative Genomics of Apomictic Root-Knot Nematodes: Hybridization, Ploidy, and Dynamic Genome Change.
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DOI：
10.1093/gbe/evx201
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发表时间：
2017-10-01
影响因子：
3.3
通讯作者：
Lunt DH
中科院分区：
文献类型：
--
作者：
Szitenberg A;Salazar-Jaramillo L;Blok VC;Laetsch DR;Joseph S;Williamson VM;Blaxter ML;Lunt DH
根结线虫是一种重要的植物寄生虫，给农业生产造成了巨大的损失。南方根结线虫（Meloidogyne incognita）是一种多食性的植物，是全球农业面临的重要问题。虽然了解它们在不同作物上的可变成功的基因组基础可能有利于未来的农业，但由于复杂的进化历史可能包含杂交，倍性变化和染色体片段化，因此对其基因组的分析具有挑战性。在这里，我们序列19个基因组，代表5种主要的根结线虫收集从不同的地理起源。我们表明，早于物种形成的混合起源内的ESTA导致每个物种拥有两个不同的基因组拷贝。此外，无融合生殖的拟南芥物种是亚三倍体，其中一个基因组的比例存在于第二个拷贝中。亚三倍体的比例因物种而异。非交叉重组的基因组的进化历史是非常动态的，非交叉重组的基因组拷贝，并作为一种机制，产生物种之间的分歧。有趣的是，自花传粉种M. floraclossis与无融合生殖物种的不同之处在于，它在其基因组的大部分中已经变成纯合的。
The root-knot nematodes (genus Meloidogyne) are important plant parasites causing substantial agricultural losses. The Meloidogyne incognita group (MIG) of species, most of which are obligatory apomicts (mitotic parthenogens), are extremely polyphagous and important problems for global agriculture. While understanding the genomic basis for their variable success on different crops could benefit future agriculture, analyses of their genomes are challenging due to complex evolutionary histories that may incorporate hybridization, ploidy changes, and chromosomal fragmentation. Here, we sequence 19 genomes, representing five species of key root-knot nematodes collected from different geographic origins. We show that a hybrid origin that predated speciation within the MIG has resulted in each species possessing two divergent genomic copies. Additionally, the apomictic MIG species are hypotriploids, with a proportion of one genome present in a second copy. The hypotriploid proportion varies among species. The evolutionary history of the MIG genomes is revealed to be very dynamic, with noncrossover recombination both homogenizing the genomic copies, and acting as a mechanism for generating divergence between species. Interestingly, the automictic MIG species M. floridensis differs from the apomict species in that it has become homozygous throughout much of its genome.