CEITEC-Central European Institute of Technology, Masaryk University, Brno, CZ-625 00, Czech Republic.
Plant Cell. 2022 Jul 4;34(7):2475-2491. doi: 10.1093/plcell/koac116.
The evolution of eukaryotic genomes is accompanied by fluctuations in chromosome number, reflecting cycles of chromosome number increase (polyploidy and centric fissions) and decrease (chromosome fusions). Although all chromosome fusions result from DNA recombination between two or more nonhomologous chromosomes, several mechanisms of descending dysploidy are exploited by eukaryotes to reduce their chromosome number. Genome sequencing and comparative genomics have accelerated the identification of inter-genome chromosome collinearity and gross chromosomal rearrangements and have shown that end-to-end chromosome fusions (EEFs) and nested chromosome fusions (NCFs) may have played a more important role in the evolution of eukaryotic karyotypes than previously thought. The present review aims to summarize the limited knowledge on the origin, frequency, and evolutionary implications of EEF and NCF events in eukaryotes and especially in land plants. The interactions between nonhomologous chromosomes in interphase nuclei and chromosome (mis)pairing during meiosis are examined for their potential importance in the origin of EEFs and NCFs. The remaining open questions that need to be addressed are discussed.
真核生物基因组的进化伴随着染色体数目的波动，反映了染色体数目的增加（多倍体和着丝粒分裂）和减少（染色体融合）的循环。虽然所有的染色体融合都是由两个或多个非同源染色体之间的 DNA 重组引起的，但真核生物利用几种降倍体的机制来减少其染色体数目。基因组测序和比较基因组学加速了对基因组间染色体共线性和大染色体重排的识别，并表明端到端染色体融合（EEF）和嵌套染色体融合（NCF）可能在真核生物染色体组的进化中发挥了比以前认为的更重要的作用。本综述旨在总结真核生物，特别是陆地植物中 EEF 和 NCF 事件的起源、频率和进化意义的有限知识。本文还研究了在有丝分裂过程中，非同源染色体在间期核中的相互作用以及染色体（错误）配对在 EEF 和 NCF 起源中的潜在重要性。讨论了仍需要解决的悬而未决的问题。
