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 Pisum and Lathyrus 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.

• Keywords
• CENH3, CENP-A, Cuscuta, Lathyrus, Luzula, Pisum, Rhynchospora, clustered centromere, holocentromere, microtubule, monocentromere, structured illumination microscopy,
• MeSH
• Cell Cycle MeSH
• Centromere metabolism   MeSH
• Chromosomes, Plant metabolism   MeSH
• Microscopy * MeSH
• Evolution, Molecular MeSH
• Plants metabolism   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

Genlisea margaretae, subgenus Genlisea, section Recurvatae (184 Mbp/1C), belongs to a plant genus with a 25-fold genome size difference and an extreme genome plasticity. Its 19 chromosome pairs could be distinguished individually by an approach combining optimized probe pooling and consecutive rounds of multicolor fluorescence in situ hybridization (mcFISH) with bacterial artificial chromosomes (BACs) selected for repeat-free inserts. Fifty-one BACs were assigned to 18 chromosome pairs. They provide a tool for future assignment of genomic sequence contigs to distinct chromosomes as well as for identification of homeologous chromosome regions in other species of the carnivorous Lentibulariaceae family, and potentially of chromosome rearrangements, in cases where more than one BAC per chromosome pair was identified.

• Keywords
• BACs, Genlisea, Karyotyping, Multicolor fluorescence in situ hybridization (mcFISH), Reprobing,
• MeSH
• Chromosomes, Plant genetics   metabolism   MeSH
• Genome Size MeSH
• Genome, Plant MeSH
• In Situ Hybridization, Fluorescence MeSH
• Magnoliopsida genetics   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH