Abstract
Introns occupy a large proportion of most of the eukaryotic species gene space. During past decade, introns status has changed. On one hand, an increasing proportion of individual introns are now identified as hosting signals required for proper gene expression and on the other hand splicing processes have proven to be implicated in all the different steps of gene expression, from 5'-capping to first round of translation, export of mRNA into cytoplasm and mRNA stability. In parallel, the intron/exon architecture of genes is described as overlapping with patterns of gene chromatin architecture. Despite these observations, the potential impact intron on gene structure is still poorly documented, intron number and intron location being usually neglected in both gene and genome organization studies.Plants have large genomes comprising both tens of thousands of genes and more than a hundred thousands of introns. Complete sequenced plant genomes therefore permit to document the consequences of intron presence into genes within a genome and to compare whether intron presence has similar impact on gene architecture between genomes of different species. We performed a comprehensive survey of the consequences of intron presence on nucleotide composition of genes in two widely divergent plant genomes (Arabidopsis thaliana and rice, Oryza sativa) and described the consequences of changes in the intron/exon structure of genes at a genome-wide scale. Our results converge to show that gene intron/exon architecture is required to properly described patterns of variation in nucleotide composition in plant genes.