A deep dive into the ancestral chromosome number and genome size of flowering plants
A deep dive into the ancestral chromosome number and genome size of flowering plants
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DOI：
10.1111/nph.16668
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发表时间：
2020-06-16
期刊：
影响因子：
9.4
通讯作者：
Peruzzi, Lorenzo
中科院分区：
文献类型：
--
作者：
Carta, Angelino;Bedini, Gianni;Peruzzi, Lorenzo
开花植物的染色体数目和基因组变异刺激了人们对被子植物祖先染色体数目的越来越多的猜测，但到目前为止，估计仍然不明确。我们使用概率方法模拟单倍体染色体数目(N)的变化，重建现存被子植物的共同祖先和单个被子植物家族最近的共同祖先的祖先染色体数目。我们独立地对1C基因组大小进化进行了分析，包括5000多个分类群。我们的分析表明被子植物的祖先单倍体染色体数目n=7，为二倍体状态，祖先1C为1.73pg。对于160个家庭，首次提供推算祖先。下降异倍体和多倍体在染色体数目进化中都起着至关重要的作用。虽然下降的异倍体在整个系统发育的早期和晚期平均分布，但多倍体主要在顶端被检测到。同样，1C基因组大小在分枝后期也显著增加(或减少)。因此，没有证据表明祖先的染色体数目和古代的多倍化事件之间存在明显的联系，这表明需要进一步的洞察来阐明基因组包装到染色体中的组织。
Chromosome number and genome variation in flowering plants have stimulated growing speculation about the ancestral chromosome number of angiosperms, but estimates so far remain equivocal. We used a probabilistic approach to model haploid chromosome number (n) changes along a phylogeny embracing more than 10 000 taxa, to reconstruct the ancestral chromosome number of the common ancestor of extant angiosperms and the most recent common ancestor for single angiosperm families. Independently, we carried out an analysis of 1C genome size evolution, including over 5000 taxa. Our analyses revealed an ancestral haploid chromosome number for angiosperms ofn = 7, a diploid status, and an ancestral 1C of 1.73 pg. For 160 families, inferred ancestralnare provided for the first time. Both descending dysploidy and polyploidy played crucial roles in chromosome number evolution. While descending dysploidy is equally distributed early and late across the phylogeny, polyploidy is detected mainly towards the tips. Similarly, 1C genome size also increases (or decreases) significantly in late-branching lineages. Therefore, no evidence exists of a clear link between ancestral chromosome numbers and ancient polyploidization events, suggesting that further insights are needed to elucidate the organization of genome packaging into chromosomes.