Description of WRRC Brachypodium distachyon T-DNA Collection

Brachypodium distachyon has recently emerged as a powerful experimental model for the grasses. A growing collection of genomic resources has been developed including a complete genome sequence, resequenced genomes, microarrays, large germplasm collections and numerous bioinformatic tools. We are adding to these resources by continuing to produce T-DNA lines and flanking sequence tags (FSTs). To improve FST sequencing efficiency, we adopted a strategy based on four dimensional pooling and Illumina sequencing. This approach, called TDNA-Seq, is being used to resequence existing Arabidopsis T-DNA collections and offers significant advantages over Sanger sequencing. Using TDNA-Seq, 10,000 lines can be sequenced simultaneously from only 40 DNA pools. We have sequenced ~18,000 T-DNA lines, 17,595 lines from the Western Regional Research Center (WRRC) and 500 lines from Canada. This gave us an additional ~27,000 FST over what we previously identified by Sanger sequencing. The distribution of T-DNA insertion site (IS) is non-uniform with fewer IS at centromeric regions. Approximately 9,000 unique genes have been tagged in this population. 27.4% of the IS reside within genes and 24% of the IS resides within 1Kb of genes. Information about the WRRC Brachypodium insertion mutant population is available online (http://brachypodium.pw.usda.gov/TDNA/). We are currently extracting DNA for the final batch of 3,600 lines to be sequenced and the additional FSTs will be available in the coming months. This gives us approximately 21,000 T-DNA lines that are available at the WRRC. We are also in the process of seed bulking and phenotypic analysis of T1 populations.