Submitted to: Plant Animal and Microbe Genomes Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/3/2003
Publication Date: 1/9/2004
Citation: Liu, Z., Moore, P.H., Ackerman, C.M., Yu, Q., Paterson, A.H., Ming, R. 2004. A primitive Y chromosome in papaya reveals that sex chromosomes evolve from autosomes. Plant Animal and Microbe Genomes Conference XI. P598, p.220. 2004
Interpretive Summary: abstract only
Technical Abstract: Eukaryotic sex chromosomes are believed to have evolved from ancestral autosomes. Those of higher plants evolved recently and independently in several taxa. Sex chromosome evolution is thought to involve suppression of recombination around the sex determination genes. The chromosomal region that is permanently heterozygous without recombination would accumulate deleterious recessive mutations and fix deleterious Y-linked mutations as favorable mutations are selected on the Y chromosome. Over time, these evolutionary processes would cause the Y chromosome to degenerate and diverge from its homolog over most or all of its length. We report a papaya primitive Y chromosome with a small male-specific region, the MSY, that is about 10% of the chromosome showing severe suppression of recombination and degeneration of DNA sequences. The MSY consists of a mosaic of conserved, X-degenerated, and ampliconic sequences. High frequencies of sequence duplications and transposable element insertions contributed to the degeneration of the MSY resulting in low gene density. This finding provides direct evidence for the origin of sex chromosomes from autosomes.