Plant cell wall degradation in insects: Recent progress on endogenous enzymes revealed by multi-omics technologies

Abstract The ability of insects to digest recalcitrant plant cell walls greatly contributes to their success worldwide. Most herbivorous insects, including phytophagous, saprophagous, and xylophagous taxa, can produce their own digestive enzymes to decompose plant cell walls, providing them an advantage by allowing for the digestion of plant biomass. Recent research using techniques involving genomics, transcriptomics, proteomics, and/or metabolomics has been offering comprehensive understanding of the mechanisms underlying plant cell wall degradation and the repertoires of the relevant endogenous digestive enzymes in the guts of insects. This review highlights recent findings about the repertoires and functions of endogenous digestive enzymes in insects such as cellulases, hemicellulases, pectinases, and lytic polysaccharide monooxygenases, and about their evolution involving multi/neofunctionalization, with special reference to termites, beetles, and stick insects.