Date: Saturday, January 14, 2012
Time: 11:20 AM
Time: 11:20 AM
Room: Royal Palm Salon 1-2
Despite the central importance of noncoding DNA in gene regulation and evolution, our understanding of the genomic extent and nature of selection on plant noncoding regions remains limited. We are combining comparative genomics with population genomics approaches to characterize the functional importance of plant noncoding regions, using the Brassicaceae. We conducted whole genome alignments of nine Brassicaceae species, including two new genome assemblies from the DOE Joint Genome Institute (Capsella rubella and Eutrema halophila) and de novo Illumina assemblies of three additional species by the VEGI consortium (Aethionema arabicum, Sisymbrium irio, and Leavenworthia alabamica). Analysis of multispecies conservation resulted in the identification of more than 90,000 conserved noncoding sequences (CNCs), ranging in size from 12 to 2000bp. Comparisons of motif patterns inside and outside of conserved motifs reveal an enrichment of known transcription factor binding sites, as well as candidate novel sites. Analysis of polymorphism and divergence in CNCs in both Arabidopsis and Capsella confirm the action of purifying selection on CNCs, but also suggest a high rate of positive selection in these regions. Our analysis indicates the predominance of weak purifying selection and positive selection in plant noncoding regions, highlighting the likely importance of these regions for functional variation and adaptive evolution.