A primitive Y chromosome in papaya marks incipient sex chromosome evolution

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 i...

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Bibliographic Details
Published in:	Nature Vol. 427; no. 6972; pp. 348 - 352
Main Authors:	Ming, Ray, Liu, Zhiyong, Moore, Paul H, Ma, Hao, Ackerman, Christine M, Ragiba, Makandar, Yu, Qingyi, Pearl, Heather M, Kim, Minna S, Charlton, Joseph W, Stiles, John I, Zee, Francis T, Paterson, Andrew H
Format:	Journal Article
Language:	English
Published:	London Nature Publishing 22-01-2004 Nature Publishing Group
Subjects:	Agronomy. Soil science and plant productions Alleles Base Sequence Biological and medical sciences Carica - genetics Carica papaya Chromosomes Chromosomes, Plant - genetics Cloning, Molecular Contig Mapping Cytogenetics Disorders of Sex Development - genetics Evolution, Molecular Flowers & plants Fundamental and applied biological sciences. Psychology Generalities. Genetics. Plant material Genes Genes, Plant - genetics Genetic Markers Genetics and breeding of economic plants Molecular biology Molecular Sequence Data Mutation Polymorphism, Genetic Sex Determination Processes Sexes Y Chromosome - genetics Genetic marker Sex chromosome Caricaceae Y-Chromosome Medicinal plant Heterozygosity Molecular evolution Sex determination Dicotyledones Angiospermae Spermatophyta Fruit tree Carica papaya
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Summary:	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.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0028-0836 1476-4687
DOI:	10.1038/nature02228