Extensive concerted evolution of rice paralogs and the road to regaining independence.
Many 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 approximately 0.4 MY since their divergence, with a gradual progression toward independent evolution of older paralogs. Since divergence from subspecies indica, approximately 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 approximately 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 approximately 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.
Wang
Xiyin
X
Plant Genome Mapping Laboratory, University of Georgia, Athens, Georgia 30602, USA.
Tang
Haibao
H
Bowers
John E
JE
Feltus
Frank A
FA
Paterson
Andrew H
AH
D003434:Crossing Over, Genetic; D019143:Evolution, Molecular; D005785:Gene Conversion; D020440:Gene Duplication; D018745:Genome, Plant; D008957:Models, Genetic; D012275:Oryza / Q000145:classification / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics; D011123:Polyploidy; D045868:Sorghum / Q000145:classification / Q000235:genetics; D013045:Species Specificity; D013997:Time Factors
D010940:Plant Proteins