Gall Wasp Transcriptomes Unravel Potential Effectors Involved in Molecular Dialogues With Oak and Rose

To gain insight into wasp factors that might be involved in the initial induction of gallson woody plants, we performed high throughput (454) transcriptome analysis of ovaries and venom glands of two cynipid gall wasps, Biorhiza pallidaand Diplolepis rosae, inducing gallson oak and rose, respectively. De novo assembled and annotated contigswere compared to sequences from phylogenetically related parasitoid wasps. The relative expression levels of contigswere estimated to identify the most expressed gene sequences in each tissue. We identify for the first time a set of maternally expressed gall waspproteins potentially involved in the interaction with the plant. Some genes highly expressed in venom glands and ovaries may act to suppress early plant defense signaling. We also identify gall waspcellulases that could be involved in observed local lysis of plant tissue following oviposition, and which may have been acquired from bacteria by horizontal gene transfer. We find no evidence of virus-related gene expression, in contrast to many non-cynipid parasitoid wasps. By exploring gall waspeffectors, this study is a first step towards understanding the molecular mechanisms underlying cynipid gallinduction in woody plants, and the recent sequencing of oak and rose genomes will enable study of plant responses to these factors.