The genome of the cereal pestSitophilus oryzae: a transposable element haven
AbstractBackgroundAmong beetles, the rice weevilSitophilus oryzaeis one of the most important pests causing extensive damage to cereal in fields and to stored grains.S. oryzaehas an intracellular symbiotic relationship (endosymbiosis) with the Gram-negative bacteriumSodalis pierantoniusand is a valuable model to decipher host-symbiont molecular interactions.ResultsWe sequenced theSitophilus oryzaegenome using a combination of short and long reads to produce the best assembly for a Curculionidae species to date. We show thatS. oryzaehas undergone successive bursts of transposable element (TE) amplification, representing 72% of the genome. In addition, we show that many TE families are transcriptionally active, and changes in their expression are associated with insect endosymbiotic state.S. oryzaehas undergone a high gene expansion rate, when compared to other beetles. Reconstruction of host-symbiont metabolic networks revealed that, despite its recent association with cereal weevils (30 Kyear),S. pierantoniusrelies on the host for several amino acids and nucleotides to survive and to produce vitamins and essential amino-acids required for insect development and cuticle biosynthesis.ConclusionsIn addition to being an agricultural pest and a valuable endosymbiotic system,S. oryzaecan be a remarkable model for studying TE evolution and regulation, along with the impact of TEs on eukaryotic genomes.