Plant & Animal Genomes XIV Conference

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

Agrobacterium-Mediated Transformation Of The Model Grass Brachypodium distachyon

John P. Vogel , Oymon M. Leong , Daniel, M. Hayden

  USDA-ARS Western Regional Research Center, 800 Buchanan St., Albany, CA, 94710, USA

Brachypodium distachyon (Brachypodium) has been proposed as a model temperate grass because its physical, genetic, and genome attributes (small stature, simple growth requirements, small genome size, availability of diploid ecotypes, annual lifecycle and self fertility) are suitable for a model plant system. Two additional requirements that are necessary before Brachypodium can be widely accepted as a model system are an Agrobacterium-mediated transformation system and a large collection of EST sequences. Biolistic transformation of Brachypodium has been previously reported. Unfortunately, due to the non-specific method of transgene integration, biolistic transformation typically results in complex transgene insertion patterns containing many copies of the transgene and substantial rearrangements of both the inserted DNA and chromosomal DNA. Such complex insertions make subsequent genetic analysis, including cloning flanking plant DNA, difficult. In contrast to biolistic transformation, Agrobacterium-mediated transformation usually results in T-DNA insertions at only one or at most a few loci. An Agrobacterium-mediated transformation protocol was developed and used to successfully transform 10 of the 19 lines tested with average efficiencies ranging from 0.4% to 14%. The diploid accession Bd21 was readily transformed. Segregation of transgenes in the T1 generation indicated that most of the lines contained an insertion at a single genetic locus. To further develop Brachypodium as a model system, we sequenced >20,000 ESTs from five cDNA libraries made from roots, stems, leaves, immature spikes or callus. A brief summary of the EST sequencing will be presented.