Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Brachypodium Species As Intermediate Models For Wheat Genomics

Mathieu CHARLES¹ , Nathalie CHOISNE² , Sylvie SAMAIN² , Nathalie BOUDET¹ , Boulos CHALHOUB¹

¹  Organization and evolution of plant genomes (OEPG), Unité de Recherche en Génomique végétale (URGV), 2 rue Gaston Crémieux, CP 5708, 91057 Evry, France.

²  GENOSCOPE – CNRG, 2 rue Gaston Crémieux, CP 5706, F- 91057 Evry Cedex, France

We are conducting a comparative genome project that aims to understand effects of polyploidy and domestication on the evolution of the genome of the wheat species (Triticum and Aegilops), in comparison to that of rice and other grass species (http://www.genoscope.cns.fr/externe/English/Projets/Projet_LE/LE.html). Brachypodium species have small genomes (130- 470 Mb, depending on the species), and in the evolution of the Pooideae, diverged from wheat later than rice, just prior to “core- pooid” genera (Draper et al. 2001). Up to 13 genomic regions covering chosen target loci are being sequenced and compared between wheat species (Triticum and Aegilops) of different ploidy levels, rice as well the species B. sylvaticum (genome size: 470 Mb) for which a BAC library is available (Foote et al. 2004). Our primary analysis shows a better conservation of micro-colinearity between wheat and Brachypodium orthologous regions than between wheat and rice. For example, sequence comparison at the hardness locus, show that genes responsible for the Hardness/softness seed quality trait in wheat are absent from the rice orthologous region whereas they are present in the B. sylvaticum orthologous region. Gene density in the B. sylvaticum genome is comparable to that of rice (one gene per 8 kb). These results illustrate that Brachypodium species may represent an intermediate model for wheat genome analysis. Additional results and analysis and our efforts to include B. distachyon (genome size: 130 Mb) in our comparative genome project will be presented.
-Draper et al. (2001), Plant Physiology127:1539-1555
-Foote et al. (2004) Funct. Integr. Genomics4: 26-33