Chinese Scientists Sequence Whole-Genome of Oryza Brachyantha

The genus Oryza, including two cultivated rice and more than twenty wild rice species, is an ideal system for plant comparative, evolutionary and functional genomics studies. The wild rice species contains valuable gene resources for rice improvement. To facilitate the utilization of these wild resources, the International Oryza Map Alignment Project (I-OMAP) was organized by Prof. Rod Wing from University of Arizona in 2009 to construct a complete genome map of all of the Oryza species and to conduct researches in evolutionary and functional genomics.

In collaboration with BGI-Shenzhen and University of Arizona, Prof. CHEN Mingsheng’s group at the Institute of Genetics and Developmental Biology, Chinese Academe of Sciences (IGDB) generated 261 Mb genome sequence of O. brachyantha.

They revealed that the compact genome of O. brachyantha resulted from recent silencing of LTR retrotransposons and massive internal deletions of ancient elements. Comparison with the rice genome indicated that many gene families were expanded in rice, where tandem duplication and gene movement mediated bydouble-strand break repair are responsible for the amplification of these genes.

They also observed that segmental and tandem duplications, further expanded by transposable element insertions, contributed to transition from euchromatin to heterochromatin in the rice genome, reflecting the dynamic nature of the Oryza genomes.

This work has been published online in Nature Communications on March 12, 2013. This work was supported by grants from the National Natural Science Foundation of China and the State Key Laboratory of Plant Genomics.