title: Duplication and DNA segmental loss in the rice genome: implications for diploidization.
abstract: * Large-scale duplication events have been recently uncovered in the rice genome, but different interpretations were proposed regarding the extent of the duplications. * Through analysing the 370 Mb genome sequences assembled into 12 chromosomes of Oryza sativa subspecies indica, we detected 10 duplicated blocks on all 12 chromosomes that contained 47% of the total predicted genes. Based on the phylogenetic analysis, we inferred that this was a result of a genome duplication that occurred c. 70 million years ago, supporting the polyploidy origin of the rice genome. In addition, a segmental duplication was also identified involving chromosomes 11 and 12, which occurred c. 5 million years ago. * Following the duplications, there have been large-scale chromosomal rearrangements and deletions. About 30-65% of duplicated genes were lost shortly after the duplications, leading to a rapid diploidization. * Together with other lines of evidence, we propose that polyploidization is still an ongoing process in grasses of polyploidy origins.
authors.affiliation: College of Life Sciences, National Laboratory of Plant Genetic Engineering and Protein Engineering, Center of Bioinformatics, Peking University, Beijing 100871, China.
authors.forename: Xiyin
authors.initials: X
authors.lastname: Wang
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Shi
authors.forename: Bailin
authors.initials: B
authors.lastname: Hao
authors.forename: Song
authors.initials: S
authors.lastname: Ge
authors.forename: Jingchu
authors.initials: J
authors.lastname: Luo
mesh_terms: D005075:Biological Evolution; D032461:Chromosomes, Plant; D020440:Gene Duplication; D018745:Genome, Plant; D012275:Oryza / Q000235:genetics*; D011003:Ploidies