Features of Evolutionarily Conserved Alternative Splicing Events Between Brassica and Arabidopsis

Alternative splicing (AS) generates multiple types of mRNAs from a single type of pre-mRNA by differential intron splicing.  It can result in new protein isoforms or down-regulation of gene expression by transcript decay.  The evolutionary conservation of AS events in plants is largely unexplored and only a small number of AS events have been identified as conserved between divergent species. We performed a large-scale analysis of cDNA data from Brassica and Arabidopsis to identify and further characterize conserved AS events.  We identified 537 conserved AS events in 485 loci.  Alternative donor and acceptor events are significantly overrepresented among conserved events, whereas intron retention and exon skipping events are underrepresented.  Conserved AS events are significantly shorter, less likely to be in the 3’UTR, and they are enriched for genes whose products function in the chloroplast. AS modified a functional domain for about half of the genes with conserved events. This study identifies many AS events that are conserved between Brassica and Arabidopsis, revealing features of conserved AS events and many AS events that may have important but uncharacterized functions.  This research is being continued on a larger scale using comparative transcriptome sequencing of Brassica rapa and Arabidopsis thaliana and initial results will be presented too.