Evolution and Diversity of the Wild Rice Oryza officinalis Complex, across Continents, Genome Types, and Ploidy Levels


Matt Shenton, Masaaki Kobayashi, Shin Terashima, Hajime Ohyanagi, Dario Copetti, Tania Hernández-Hernández, Jianwei Zhang, Nobuko Ohmido, Masahiro Fujita, Atsushi Toyoda, Hiroshi Ikawa, Asao Fujiyama, Hiroyasu Furuumi, Toshie Miyabayashi, Takahiko Kubo,
David Kudrna, Rod Wing, Kentaro Yano, Ken-Ichi Nonomura, Yutaka Sato, Nori Kurata
Genome Biology and Evolution, Volume 12, Issue 4, April 2020, Pages 413–428, https://doi.org/10.1093/gbe/evaa037
Published: 03 March 2020


The Oryza officinalis complex is the largest species group in Oryza, with more than nine species from four continents, and is a tertiary gene pool that can be exploited in breeding programs for the improvement of cultivated rice. Most diploid and tetraploid members of this group have a C genome. Using a new reference C genome for the diploid species O. officinalis, and draft genomes for two other C genome diploid species Oryza eichingeri and Oryza rhizomatis, we examine the influence of transposable elements on genome structure and provide a detailed phylogeny and evolutionary history of the Oryza C genomes. The O. officinalis genome is 1.6 times larger than the A genome of cultivated Oryza sativa, mostly due to proliferation of Gypsy type long-terminal repeat transposable elements, but overall syntenic relationships are maintained with other Oryza genomes (A, B, and F). Draft genome assemblies of the two other C genome diploid species, Oryza eichingeri and Oryza rhizomatis, and short-read resequencing of a series of other C genome species and accessions reveal that after the divergence of the C genome progenitor, there was still a substantial degree of variation within the C genome species through proliferation and loss of both DNA and long-terminal repeat transposable elements. We provide a detailed phylogeny and evolutionary history of the Oryza C genomes and a genomic resource for the exploitation of the Oryza tertiary gene pool.

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