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TitleExtensive Concerted Evolution of Rice Paralogs and the Road to Regaining Independence
AuthorsXiyin Wang, Haibao Tang, John E. Bowers, Frank A. Feltus and Andrew H. Paterson
PublicationGenetics 177: 1753-1763
AbstractMany genes duplicated by whole-genome duplications (WGDs) are more similar to one another than
expected. We investigated whether concerted evolution through conversion and crossing over, well-known
to affect tandem gene clusters, also affects dispersed paralogs. Genome sequences for two Oryza
subspecies reveal appreciable gene conversion in the ~0.4 MY since their divergence, with a gradual
progression toward independent evolution of older paralogs. Since divergence from subspecies indica,
~8% of japonica paralogs produced 5-7 MYA on chromosomes 11 and 12 have been affected by gene
conversion and several reciprocal exchanges of chromosomal segments, while ~70-MY-old "paleologs"
resulting from a genome duplication (GD) show much less conversion. Sequence similarity analysis in
proximal gene clusters also suggests more conversion between younger paralogs. About 8% of paleologs
may have been converted since rice-sorghum divergence ~41 MYA. Domain-encoding sequences are
more frequently converted than nondomain sequences, suggesting a sort of circularity - that sequences
conserved by selection may be further conserved by relatively frequent conversion. The higher level of
concerted evolution in the 5-7 MY-old segmental duplication may reflect the behavior of many genomes
within the first few million years after duplication or polyploidization.

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.: 2009 :: Barry Marler :: Plant Genome Mapping Laboratory :: University of Georgia