Section: New Results
Small RNAs catalog in oilseed rape
Polyploidy – and notably allopolyploidy that involves interspecific hybridization – has played a major role in the evolution of plants, partly because this process is often associated with genomic structure and expression changes. Homeologous exchanges (HE) – i.e. between the constituent subgenomes– have been demonstrated to be frequent in allopolyploids and could be involved in the origin and maintenance of polyploids. While their influence on gene content has poorly been studied until recently, little is known about their impact on gene expression. Together with K. Alix (Inra Moulon), we have analyzed the impact of HEs that have been characterized in resynthesized oilseed rapes, on the repertoire of micro RNAs. Our main objective was to assess the relations that could exist between structural variation and modifications of gene expression through changes in miRNA regulation. The analysis was based on the small RNA-seq catalog obtained with the bioinformatic tool miRkwood, developed in Bonsai . We have built a microRNA database for the diploid subgenomes AA from Brassica rapa and CC for Brassica oleracea that correspond to the progenitors of the resynthesized Brassica napus allotetraploids (AACC). Integrating miRNA prediction and genomic location of HEs allowed us to infer relationships between microRNA restructuring and non-additivity of gene expression in polyploid hybrids.