Genome-wide survey of alternative splicing in the grass Brachypodium distachyon: a emerging model biosystem for plant functional genomics

A draft sequence of the genome of Brachypodium distachyon, the emerging grass model, was recently released. This represents a unique opportunity to determine its functional diversity compared to the genomes of other model species. Using homology mapping of assembled expressed sequence tags with chromosome scale pseudomolecules, we identified 128 alternative splicing events in B. distachyon. Our study identified that retention of introns is the major type of alternative splicing events (53%) in this plant and highlights the prevalence of splicing site recognition for definition of introns in plants. We have analyzed the compositional profiles of exon-intron junctions by base-pairing nucleotides with U1 snRNA which serves as a model for describing the possibility of sequence conservation. The alternative splicing isoforms identified in this study are novel and represent one of the potentially biologically significant means by which B. distachyon controls the function of its genes. Our observations serve as a basis to understand alternative splicing events of cereal crops with more complex genomes, like wheat or barley.