Down, then up: non-parallel genome size changes and a descending chromosome series in a recent radiation of the Australian allotetraploid plant species, Nicotiana section Suaveolentes (Solanaceae).
Down, then up: non-parallel genome size changes and a descending chromosome series in a recent radiation of the Australian allotetraploid plant species, Nicotiana section Suaveolentes (Solanaceae).
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DOI：
10.1093/aob/mcac006
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发表时间：
2023-02-07
期刊：
影响因子：
4.2
通讯作者：
中科院分区：
文献类型：
--
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基因组大小和染色体数目在多大程度上协同进化还不清楚，特别是在多倍体（全基因组复制）之后，当基因组恢复到二倍体样状态（二倍体化）时。我们研究了46种异源四倍体烟草组Suaveolentes（茄科），形成于600万年前，辐射在澳大利亚干旱的中心。我们分析了新评估的基因组大小和染色体数目的限制性位点相关的核DNA（RADseq）系统发育框架的背景下。RADseq生成了一个支持良好的系统发育树，其中来自每个物种的多个加入物形成了独特的遗传簇。染色体数目和基因组大小分别为n = 2x = 15至24和2.7至5.8 pg/1C核。基因组大小和染色体数目都会减少，但既不一致也不平行。染色体数目最少的物种（n = 15-18）并不具有最小的基因组大小，尽管N. heterantha保留了祖先的染色体互补，n = 2x = 24，但它具有最小的基因组大小，甚至小于祖先二倍体的现代代表。结果表明，在染色体数目阈值，n = 20，低于该基因组大小增加，一个现象可能解释为减少重组率在更少的染色体平行发生在基因组大小和染色体数目的减少。我们假设，更普遍地在植物中，多倍体化后基因组大小的主要减少发生在染色体数目仍然很高的时候，因为在这些阶段，反转录转座子和其他重复元件的消除更有效。一旦这种主要的基因组大小变化已经完成，然后异倍体染色体减少发生重组这些较小的基因组，产生具有小基因组和低染色体数目的物种，如在许多一年生被子植物中观察到的那些，包括拟南芥。
The extent to which genome size and chromosome numbers evolve in concert is little understood, particularly after polyploidy (whole-genome duplication), when a genome returns to a diploid-like condition (diploidization). We study this phenomenon in 46 species of allotetraploid Nicotiana section Suaveolentes (Solanaceae), which formed <6 million years ago and radiated in the arid centre of Australia. We analysed newly assessed genome sizes and chromosome numbers within the context of a restriction site-associated nuclear DNA (RADseq) phylogenetic framework. RADseq generated a well-supported phylogenetic tree, in which multiple accessions from each species formed unique genetic clusters. Chromosome numbers and genome sizes vary from n = 2x = 15 to 24 and 2.7 to 5.8 pg/1C nucleus, respectively. Decreases in both genome size and chromosome number occur, although neither consistently nor in parallel. Species with the lowest chromosome numbers (n = 15–18) do not possess the smallest genome sizes and, although N. heterantha has retained the ancestral chromosome complement, n = 2x = 24, it nonetheless has the smallest genome size, even smaller than that of the modern representatives of ancestral diploids. The results indicate that decreases in genome size and chromosome number occur in parallel down to a chromosome number threshold, n = 20, below which genome size increases, a phenomenon potentially explained by decreasing rates of recombination over fewer chromosomes. We hypothesize that, more generally in plants, major decreases in genome size post-polyploidization take place while chromosome numbers are still high because in these stages elimination of retrotransposons and other repetitive elements is more efficient. Once such major genome size change has been accomplished, then dysploid chromosome reductions take place to reorganize these smaller genomes, producing species with small genomes and low chromosome numbers such as those observed in many annual angiosperms, including Arabidopsis.
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影响因子：
3.7
作者：
Baird NA;Etter PD;Atwood TS;Currey MC;Shiver AL;Lewis ZA;Selker EU;Cresko WA;Johnson EA
通讯作者：
Johnson EA
DOI：
10.1111/curt.12410
发表时间：
2021-09-01
期刊：
Curtis's Botanical Magazine
影响因子：
--
作者：
Chase, Mark W.;Christenhusz, Maarten J. M.;Paun, Ovidiu
通讯作者：
Paun, Ovidiu
DOI：
10.1111/curt.12241
发表时间：
2018-10-01
期刊：
Curtis's Botanical Magazine
影响因子：
--
作者：
Chase, Mark W.;Christenhusz, Maarten J. M.;Fay, Michael F.
通讯作者：
Fay, Michael F.
影响因子：
6.5
作者：
Brandrud, Marie K.;Baar, Juliane;Paun, Ovidiu
通讯作者：
Paun, Ovidiu
影响因子：
4.2
作者：
Chase, MW;Knapp, S;Parokonny, AS
通讯作者：
Parokonny, AS