The B chromosome of Pseudococcus viburni: A selfish chromosome that exploits whole-genome meiotic drive

Isabelle Vea, Andrés García de la Filia, Kamil S. Jaron, Scott E. J. Barlow, Marion Herbette, Andrew J. Mongue, Ross Nelson, Francisco J. Ruiz-Ruano, Laura Ross*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Meiosis is generally a fair process: each chromosome has a 50% chance of being included into each gamete. However, meiosis can become aberrant with some chromosomes having a higher chance of making it into gametes than others. Yet, why and how such systems evolve remains unclear. Here, we study the unusual reproductive genetics of mealybugs, where only maternal-origin chromosomes are included in gametes during male meiosis, while paternal chromosomes are eliminated. One species-Pseudococcus viburni-has a segregating B chromosome that drives by escaping paternal genome elimination. We present whole genome and gene expression data from lines with and without B chromosomes. We identify B-linked sequences including 204 protein-coding genes and a satellite repeat that makes up a significant proportion of the chromosome. The few paralogs between the B and the core genome are distributed throughout the genome, arguing against a simple, or at least recent, chromosomal duplication of one of the autosomes to create the B. We do, however, find one 373 kb region containing 146 genes that appears to be a recent translocation. Finally, we show that while many B-linked genes are expressed during meiosis, most of these are encoded on the recently translocated region. Only a small number of B-exclusive genes are expressed during meiosis. Of these, only one was overexpressed during male meiosis, which is when the drive occurs: an acetyltransferase involved in H3K56Ac, which has a putative role in meiosis and is, therefore, a promising candidate for further studies.

Original languageEnglish
Article numberevae257
Number of pages19
JournalGenome Biology and Evolution
Volume17
Issue number1
Early online date29 Jan 2025
DOIs
Publication statusPublished - Jan 2025

Keywords / Materials (for Non-textual outputs)

  • B chromosomes
  • paternal genome elimination
  • genomic conflict
  • mealybugs

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