Department of Biology, University of Puget Sound, Tacoma, Washington 98416 USA.
Am J Bot. 2009 Sep;96(9):1656-64. doi: 10.3732/ajb.0800270. Epub 2009 Aug 13.
Allopolyploids contain complete sets of chromosomes from two or more different progenitor species. Because allopolyploid hybridization can lead to speciation, allopolyploidy is an important mechanism in evolution. Meiotic instability in early-generation allopolyploids contributes to high lethality, but less is known about mitotic fidelity in allopolyploids. We compared mitotic stability in resynthesized Arabidopsis suecica-like neoallopolyploids with that in 13 natural lines of A. suecica (2n = 4x = 26). We used fluorescent in situ hybridization to distinguish the chromosomal contribution of each progenitor, A. thaliana (2n = 2x =10) and A. arenosa (2n = 4x = 32). Surprisingly, cells of the paternal parent A. arenosa had substantial aneuploidy, while cells of the maternal parent A. thaliana were more stable. Both natural and resynthesized allopolyploids had low to intermediate levels of aneuploidy. Our data suggest that polyploidy in Arabidopsis is correlated with aneuploidy, but varies in frequency by species. The chromosomal composition in aneuploid cells within individuals was variable, suggesting somatic mosaicisms of cell lineages, rather than the formation of distinct, stable cytotypes. Our results suggest that somatic aneuploidy can be tolerated in Arabidopsis polyploids, but there is no evidence that this type of aneuploidy leads to stable novel cytotypes.
异源多倍体包含来自两个或更多不同祖先物种的整套染色体。由于异源多倍体杂交可以导致物种形成，因此异源多倍体是进化中的一个重要机制。早期异源多倍体的减数分裂不稳定导致高致死率，但对异源多倍体的有丝分裂保真度知之甚少。我们比较了合成的拟南芥-like 新异源多倍体与 13 种天然拟南芥 (2n = 4x = 26) 之间的有丝分裂稳定性。我们使用荧光原位杂交来区分每个祖先，拟南芥 (2n = 2x =10) 和 A. arenosa (2n = 4x = 32) 的染色体贡献。令人惊讶的是，父本 A. arenosa 的细胞具有大量的非整倍体，而母本 A. thaliana 的细胞则更稳定。天然和合成的异源多倍体都具有低到中等水平的非整倍体。我们的数据表明，拟南芥中的多倍体与非整倍体相关，但不同物种的频率不同。个体中非整倍体细胞的染色体组成是可变的，这表明细胞谱系的体细胞镶嵌，而不是形成独特的、稳定的细胞型。我们的结果表明，体细胞非整倍体可以在拟南芥多倍体中被容忍，但没有证据表明这种类型的非整倍体导致稳定的新细胞型。
