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

The Cerambycidae, also known as longhorned beetles, are a family of plant-feeding beetles (Phytophaga) that specifically feed on wood (xylophagy). Woody tissues lack essential nutrients for insect development, and long-chain polysaccharides of wood structures make it difficult for beetles to degrade the plant cell wall within their digestive systems. However, Cerambycidae have evolved in this challenging environment by successfully breaking down polysaccharides and acquiring nutrients from woody tissues. Previous studies identified that cerambycid beetles possess endogenous plant cell wall degrading enzymes (PCWDEs). However, within the Cerambycidae family, consisting of eight subfamilies, research on PCWDEs has focused on only one subfamily (Lamiinae), leaving very little known about PCWDEs in other subfamilies. My project provides the first comprehensive study of genomic data from the family Cerambycidae, using 23 species of beetles representing six subfamilies. I have shown that most cerambycid beetles are not fully dependent on microorganisms or symbionts to digest plant matter but possess their digestive enzymes. Enzyme-encoding genes have been horizontally acquired from various microbial donors and have evolved by gene duplications after these HGT events. These findings are an excellent starting point for studying the complementary function and evolution of endogenous PCWDEs in cerambycid and other phytophagous beetles.