Comparing low coverage random shotgun sequence data from Brassica oleracea and Oryza sativa genome sequence for their ability to add to the annotation of Arabidopsis thaliana

Abstract

Since the completion of the Arabidopsis thaliana genome sequence, there is an ongoing effort to annotate the genome as accurately as possible. Comparing genome sequences of related species complements the current annotation strategies by identifying genes and improving gene structure. A total of 595,321 Brassica oleracea shotgun reads were sequenced by TIGR (The Institute for Genome Research) and the collaboration of Washington University and Cold Spring Harbor. Vicogenta (a genome viewer based on GMOD and GBrowse) was created to view the current annotation and sequence alignments for Arabidopsis. Brassica reads were compared with the Arabidopsis genome and proteome databases using BLAST. Hypothetical genes and conserved unannotated regions on the short arm of chromosome 4 from Arabidopsis were experimentally verified using RT–PCR. We were able to improve the Arabidopsis annotation by identifying 25 genes that were missed, and confirming expression of 43 hypothetical genes in Arabidopsis. We were also able to detect conservation in genes whose transcription is normally suppressed due to methylation. We also examined how useful the O. sativa genome and ESTs from other species are, compared with Brassica, in improving the Arabidopsis annotation.