Genomic dissection of an extended phenotype: Oak galling by a cynipid gall wasp

摘要: Galls are plant tissues whose development is induced by another organism for the inducer's benefit. 30,000 arthropod species induce galls, and in most cases inducing effectors target systems unknown. Cynipid gall wasps a speciose monophyletic radiation that structurally complex galls on oaks other plants. We used model system comprising wasp Biorhiza pallida oak Quercus robur to characterise inducer host gene expression at defined stages through of galled ungalled tissues, tested alternative hypotheses origin type galling metabolic pathways involved. Oak patterns diverged markedly during normal buds. Young showed elevated genes similar legume root nodule Nod factor-induced early nodulin (ENOD) developmental parallels with In contrast, mature substantially different leaves. While transcripts could be functionally annotated, many interest were novel. found no evidence involvement third-party symbionts induction, effector delivery using virus-like-particles, or gallwasp coding hormones. Many differentially highly expressed young larvae encoded secretory peptides, which we hypothesise proteins exported tissues. Specifically, propose arabinogalactan chitinases interact generate somatic embryogenesis-like process surrounding larvae. Gall also encoding multiple cell wall degrading enzymes (PCWDEs). These have functional orthologues cynipids but not figitid parasitoid sister groups, suggesting they may evolutionary innovations associated cynipid induction.