Plant Y-chromosome degeneration is retarded by haploid purifying selection.
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ABSTRACT: Sex chromosomes evolved many times independently in many different organisms. According to the currently accepted model, X- and Y-chromosomes evolve from a pair of autosomes via a series of inversions leading to step-wise expansion of a non-recombining region on the Y chromosome (NRY) and the consequential degeneration of genes trapped in the NRY. Our results suggest that plants represent an exception to this rule due to their unique life-cycle that includes alteration of diploid and haploid generations and widespread haploid expression of genes in plant gametophytes. Using a new high-throughput approach we identified over 400 new genes expressed from X- and Y- chromosomes in Silene latifolia, a plant that evolved sex chromosomes about 10 million years ago. Y-linked genes show faster accumulation of amino-acid replacements and loss of expression, compared to X-linked genes. These degenerative processes are significantly less pronounced in more constrained genes and genes that are likely exposed to haploid-phase selection. This may explain why plants retain hundreds of expressed Y-linked genes despite millions of years of Y-chromosome degeneration, while animal Y-chromosomes are almost completely degenerate.
ORGANISM(S): Silene vulgaris Silene latifolia
PROVIDER: GSE30958 | GEO | 2012/07/30
SECONDARY ACCESSION(S): PRJNA146235
REPOSITORIES: GEO
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