Unzipped genome assemblies of polyploid root-knot nematodes reveal unusual and clade-specific telomeric repeats
Ana Paula Zotta Mota, Georgios Koutsovoulos, Laetitia Perfus‐Barbeoch, Evelin Despot-Slade, Karine Labadie, Jean‐Marc Aury, Karine Robbe-Sermesant, Marc Bailly‐Bechet, Caroline Belser, Arthur Péré, Corinne Rancurel, Djampa Kozlowski, Rahim Hassanaly-Goulamhoussen, Martine Da Rocha, Benjamin Noël, Nevenka Meštrović, Patrick Wincker, Étienne Danchin
Abstract
Using long-read sequencing, we assembled and unzipped the polyploid genomes of Meloidogyne incognita, M. javanica and M. arenaria, three of the most devastating plant-parasitic nematodes. We found the canonical nematode telomeric repeat to be missing in these and other Meloidogyne genomes. In addition, we find no evidence for the enzyme telomerase or for orthologs of C. elegans telomere-associated proteins, suggesting alternative lengthening of telomeres. Instead, analyzing our assembled genomes, we identify species-specific composite repeats enriched mostly at one extremity of contigs. These repeats are G-rich, oriented, and transcribed, similarly to canonical telomeric repeats. We confirm them as telomeric using fluorescent in situ hybridization. These repeats are mostly found at one single end of chromosomes in these species. The discovery of unusual and specific complex telomeric repeats opens a plethora of perspectives and highlights the evolutionary diversity of telomeres despite their central roles in senescence, aging, and chromosome integrity.