Evidence for degeneration of the Y chromosome in the dioecious plant Silene latifolia

Curr Biol. 2008 Apr 8;18(7):545-9. doi: 10.1016/j.cub.2008.03.023.


The human Y--probably because of its nonrecombining nature--has lost 97% of its genes since X and Y chromosomes started to diverge [1, 2]. There are clear signs of degeneration in the Drosophila miranda neoY chromosome (an autosome fused to the Y chromosome), with neoY genes showing faster protein evolution [3-6], accumulation of unpreferred codons [6], more insertions of transposable elements [5, 7], and lower levels of expression [8] than neoX genes. In the many other taxa with sex chromosomes, Y degeneration has hardly been studied. In plants, many genes are expressed in pollen [9], and strong pollen selection may oppose the degeneration of plant Y chromosomes [10]. Silene latifolia is a dioecious plant with young heteromorphic sex chromosomes [11, 12]. Here we test whether the S. latifolia Y chromosome is undergoing genetic degeneration by analyzing seven sex-linked genes. S. latifolia Y-linked genes tend to evolve faster at the protein level than their X-linked homologs, and they have lower expression levels. Several Y gene introns have increased in length, with evidence for transposable-element accumulation. We detect signs of degeneration in most of the Y-linked gene sequences analyzed, similar to those of animal Y-linked and neo-Y chromosome genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromosomes, Plant*
  • DNA Transposable Elements
  • Evolution, Molecular*
  • Gene Expression
  • Genes, Plant*
  • Introns
  • Silene / genetics*
  • Y Chromosome


  • DNA Transposable Elements