A primitive Y chromosome in papaya marks incipient sex chromosome evolution

Zhiyong Liu, Paul H. Moore, Hao Ma, Christine M. Ackerman, Makandar Ragiba, Qingyi Yu, Heather M. Pearl, Minna S. Kim, Joseph W. Charlton, John I. Stiles, Francis T. Zee, Andrew H. Paterson, Ray Ming

Research output: Contribution to journalArticlepeer-review


Many diverse systems for sex determination have evolved in plants and animals. One involves physically distinct (heteromorphic) sex chromosomes (X and Y, or Z and W) that are homozygous in one sex (usually female) and heterozygous in the other (usually male). Sex chromosome evolution is thought to involve suppression of recombination around the sex determination genes, rendering permanently heterozygous a chromosomal region that may then accumulate deleterious recessive mutations by Muller's ratchet, and fix deleterious mutations by hitchhiking as nearby favourable mutations are selected on the Y chromosome. Over time, these processes may cause the Y chromosome to degenerate and to diverge from the X chromosome over much of its length; for example, only 5% of the human Y chromosome still shows X-Y recombination. Here we show that papaya contains a primitive Y chromosome, with a male-specific region that accounts for only about 10% of the chromosome but has undergone severe recombination suppression and DNA sequence degeneration. This finding provides direct evidence for the origin of sex chromosomes from autosomes.

Original languageEnglish (US)
Pages (from-to)348-352
Number of pages5
Issue number6972
StatePublished - Jan 22 2004
Externally publishedYes

ASJC Scopus subject areas

  • General


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