Evolution of xylophagy in longhorned beetles: Diversity, evolutionary history and functional characterization of plant cell wall degrading enzymes in beetles of the family Cerambycidae

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The charismatic longhorned beetles (Coleoptera: Cerambycidae) are part of the most diverse group of wood-feeding (xylophagous) animals on Earth. Larvae of these beetles have evolved to thrive on a highly challenging and sub-optimal environment - wood material - where they have to cope with the structural polysaccharides of the plant cell wall which make the bulk of their food. Earlier research indicated that cerambycid beetle larvae break down cellulose, hemicelluloses and pectins themselves by producing plant cell wall degrading enzymes (PCWDEs), independent of symbionts. Yet, the corresponding genes and the way they evolved remain elusive in this group of beetles. By combining gene discovery by sequencing beetle midgut transcriptome using RNA-Seq, to phylogenetic analyses and rapid screening of enzymatic activity by expressing the corresponding cDNAs in heterologous expression systems, this project aims to identify and characterize the genes encoding PCWDEs and to determine their evolutionary history in Cerambycidae. This research will provide information on how host plants and feeding behavior have shaped the composition of these gene families during the evolution of Cerambycidae; and on how PCWDEs contributed to build and maintain the biodiversity of this family of beetles. This project also opens the exciting possibility that screening the gut transcriptome of longhorned beetles represents an alternative to microorganisms for the discovery of new and better PCWDEs for use in industrial biotechnology, in particular for the improvement of biofuel production from plant biomass.