重复多倍体棉花基因组和可纺棉花纤维的进化

来源：仪方生物 www.yeslab.com

多倍体具有多种性能，例如高纤维产量及四倍体在同环境下较二倍体有跟高的质量。我们发现突然的4-6倍体增加发生在大约六千万年前，而异源多倍体聚合多种Gossypium棉花基因组是在1-2千万年前，在优质棉花（Gossypium hirsutum andGossypium barbadense）中给予30-36倍重复的祖先被子植物的基因，被子植物测序中发现遗传复杂性仅类似于甘蓝。在异源多倍体之前的起初进化是通过比较可纺棉Gossypium herbaceum A和非可纺棉 Gossypium longicalyx F彼此以及非可纺棉的Gossypium raimondii的外围基因组来阐明的。G. hirsutum AtDt品种的序列揭示了许多非互惠DNA之间的交换亚基因组可能是导致表型的更新和/或其他突发特性，如生态适应性多倍体。在G.hirsutum中，大多数DNA水平重组等位基因是从D基因组祖原生到新世界栖息地和旧世界A基因组可纺棉的进化。功能距离基因在远端的协同表达，包括一个核线粒体DNA块，可能解释棉花纤维数量性状位点影响多样特性。通过比较二倍体祖先及外群，新出现的特性在其他多倍体上比比皆是，特别是被子植物。

Repeated polyploidization of Gossypium genomes and the evolution of spinnable cotton fibres

Andrew H. Paterson1, Jonathan F. Wendel2, Heidrun Gundlach3, Hui Guo1, Jerry Jenkins4,5, Dianchuan Jin6, Danny Llewellyn7,

Polyploidy often confers emergent properties, such as the higher fibre productivity and quality of tetraploid cottons than diploid cottons bred for the same environments1. Here we show that an abrupt five- to sixfold ploidy increase approximately 60 million years (Myr) ago, and allopolyploidy reuniting divergent Gossypium genomes approximately 1–2 Myr ago2, conferred about 30–36-fold duplication of ancestral angiosperm (flowering plant) genes in elite cottons (Gossypium hirsutum andGossypium barbadense), genetic complexity equalled only by Brassica 3 among sequenced angiosperms. Nascent fibre evolution, before allopolyploidy, is elucidated by comparison of spinnable-fibred Gossypium herbaceum A and non-spinnable Gossypium longicalyx F genomes to one another and the outgroup D genome of non-spinnable Gossypium raimondii. The sequence of a G. hirsutum AtDt (in which ‘t’ indicates tetraploid) cultivar reveals many non-reciprocal DNA exchanges between subgenomes that may have contributed to phenotypic innovation and/or other emergent properties such as ecological adaptation by polyploids. Most DNA-level novelty in G. hirsutum recombines alleles from the D-genome progenitor native to its New World habitat and the Old World A-genome progenitor in which spinnable fibre evolved. Coordinated expression changes in proximal groups of functionally distinct genes, including a nuclear mitochondrial DNA block, may account for clusters of cotton-fibre quantitative trait loci affecting diverse traits. Opportunities abound for dissecting emergent properties of other polyploids, particularly angiosperms, by comparison to diploid progenitors and outgroups.