The centromere is a complex chromosomal locus that plays one of the most important roles in the process of chromosome segregation. Abnormalities in this region cause numerous disorders such as cell death, aneuploidy, infertility and cancer. Although centromeres have a conserved function, centromere-specific histone H3 (CenH3) and centromeric DNA are rapidly evolving. While most eukaryotes have a single regional centromere, some plant and animal species have holocentromeres distributed at multiple sites along the chromosome length. The genome organization and chromatin composition of holocentric chromosomes are poorly understood. Our previous results suggest a unique cluster-like organization of holocentromeres and the duplication of a centromere-specific CenH3 gene in both mitotic and meiotic Meloidogyne nematodes. The first aim of this proposal is to investigate the long-range organization, genome dynamics and environment of the holocentromere in Meloidogyne incognita and its congenerics using the new, long-reads based assemblies. The occurrence of two CenH3 paralogs in meiotic Meloidogyne species raises the possibility of subfunctionalization of CenH3 paralogs. Therefore, the second aim of the project is to reveal the putative difference between the CenH3 chromatin of the holocentromere in mitosis and meiosis using meiotic Meloidogyne species. The possible subspecialization of CenH3 in mitosis and meiosis in Meloidogyne species provides a unique opportunity to understand the functions of CenH3 in the centromere. In addition to investigating the genomic and epigenomic properties of the holocentromere, our study will also shed light on different aspects of genome architecture and evolution that are influenced by the organization of the unusual centromere.