Centromeres are essential regions of eukaryotic chromosomes responsible for the formation of kinetochore complexes, which connect to spindle microtubules during cell division. Notably, although centromeres maintain a conserved function in chromosome segregation, the underlying DNA sequences are diverse both within and between species and are predominantly repetitive in nature. The repeat content of centromeres includes high-copy tandem repeats (satellites), and/or specific families of transposons. The functional region of the centromere is defined by loading of a specific histone 3 variant (CENH3), which nucleates the kinetochore and shows dynamic regulation. In many plants, the centromeres are composed of satellite repeat arrays that are densely DNA methylated and invaded by centrophilic retrotransposons. In some cases, the retrotransposons become the sites of CENH3 loading. We review the structure of plant centromeres, including monocentric, holocentric, and metapolycentric architectures, which vary in the number and distribution of kinetochore attachment sites along chromosomes. We discuss how variation in CENH3 loading can drive genome elimination during early cell divisions of plant embryogenesis. We review how epigenetic state may influence centromere identity and discuss evolutionary models that seek to explain the paradoxically rapid change of centromere sequences observed across species, including the potential roles of recombination. We outline putative modes of selection that could act within the centromeres, as well as the role of repeats in driving cycles of centromere evolution. Although our primary focus is on plant genomes, we draw comparisons with animal and fungal centromeres to derive a eukaryote-wide perspective of centromere structure and function.

中文翻译：

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植物着丝粒的结构、功能和进化

着丝粒是真核染色体的重要区域，负责形成着丝粒复合体，在细胞分裂过程中与纺锤体微管相连。值得注意的是，尽管着丝粒在染色体分离中保持保守的功能，但物种内部和物种之间的潜在 DNA 序列是不同的，并且本质上主要是重复的。着丝粒的重复内容包括高拷贝串联重复序列（卫星）和/或特定的转座子家族。着丝粒的功能区域是通过加载特定的组蛋白 3 变体 (CENH3) 来定义的，该变体使着丝粒成核并显示出动态调节。在许多植物中，着丝粒由卫星重复阵列组成，这些卫星重复阵列被密集的 DNA 甲基化并被嗜心反转录转座子侵入。在某些情况下，逆转录转座子成为 CENH3 加载的位点。我们回顾了植物着丝粒的结构，包括单着丝粒、全着丝粒和间多着丝粒结构，它们沿染色体着丝粒附着位点的数量和分布各不相同。我们讨论了 CENH3 负载的变化如何在植物胚胎发生的早期细胞分裂过程中驱动基因组消除。我们回顾了表观遗传状态如何影响着丝粒身份，并讨论了进化模型，这些模型试图解释跨物种观察到的着丝粒序列的矛盾快速变化，包括重组的潜在作用。我们概述了可能在着丝粒内起作用的假定选择模式，以及重复在着丝粒进化的驱动周期中的作用。尽管我们的主要关注点是植物基因组，但我们与动物和真菌着丝粒进行比较，以获得着丝粒结构和功能的真核生物视角。