Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466 Seeland, Germany.
Biology Centre, Czech Academy of Sciences, 37005 České Budějovice, Czech Republic.
Int J Mol Sci. 2020 May 15;21(10):3488. doi: 10.3390/ijms21103488.
Centromeres are essential for proper chromosome segregation to the daughter cells during mitosis and meiosis. Chromosomes of most eukaryotes studied so far have regional centromeres that form primary constrictions on metaphase chromosomes. These monocentric chromosomes vary from point centromeres to so-called "meta-polycentromeres", with multiple centromere domains in an extended primary constriction, as identified in and species. However, in various animal and plant lineages centromeres are distributed along almost the entire chromosome length. Therefore, they are called holocentromeres. In holocentric plants, centromere-specific proteins, at which spindle fibers usually attach, are arranged contiguously (line-like), in clusters along the chromosomes or in bands. Here, we summarize findings of ultrastructural investigations using immunolabeling with centromere-specific antibodies and super-resolution microscopy to demonstrate the structural diversity of plant centromeres. A classification of the different centromere types has been suggested based on the distribution of spindle attachment sites. Based on these findings we discuss the possible evolution and advantages of holocentricity, and potential strategies to segregate holocentric chromosomes correctly.
着丝粒对于有丝分裂和减数分裂过程中向子细胞正确分离染色体至关重要。迄今为止，大多数已研究的真核生物的染色体具有区域着丝粒，这些着丝粒在中期染色体上形成主要的缢痕。这些单中心染色体的着丝粒从点状到所谓的“亚多中心”（multiple centromere domains in an extended primary constriction）不等，如 和 物种中所确定的那样。然而，在各种动物和植物谱系中，着丝粒沿着几乎整个染色体长度分布。因此，它们被称为全着丝粒（holocentromeres）。在全着丝粒植物中，着丝粒特异性蛋白（centromere-specific proteins），通常附着在纺锤体纤维上，沿着染色体成簇或以带的形式连续排列（线状）。在这里，我们总结了使用针对着丝粒特异性抗体的免疫标记和超分辨率显微镜进行的超微结构研究的结果，以证明植物着丝粒的结构多样性。根据纺锤体附着位点的分布，提出了不同着丝粒类型的分类。基于这些发现，我们讨论了全着丝粒的可能进化和优势，以及正确分离全着丝粒染色体的潜在策略。
