Trehalase expansion and functional divergence in the evolution of insect trehalose metabolism

How conserved metabolic pathways diversify to support lineage-specific physiological adaptation remains a fundamental question in evolutionary biology. Trehalose is a central metabolic regulator in many animals whose turnover is controlled by trehalase (Treh), yet the evolutionary diversification of Treh across animals and its contribution to metabolic adaptation remain poorly understood. Across 808 animal genomes, Treh was predominantly retained as a single copy in vertebrates, with apparent absence or putative pseudogenization in some species, whereas it underwent recurrent expansion in insects. Gene expansion was concentrated in Treh1 , particularly in Hemiptera, Coleoptera, and Lepidoptera, whereas Treh2 almost remained single copy. Lepidoptera retained a conserved Treh1a – Treh1b tandem pair. To investigate their functional roles, we disrupted each paralog in Bombyx mori . Both mutants had reduced adult body mass and trehalase activity, with lower larval body weights observed under the artificial diet but not on fresh mulberry leaves. Transcriptomic and metabolomic profiling revealed shared as well as genotype-specific responses. Functional analysis in B. mori demonstrated overlapping but non-identical physiological and transcriptional effects of these paralogs. Treh is predominantly single copy in vertebrates but has undergone recurrent, Treh1 -biased expansion in insects. Our findings provide a comparative and functional framework for understanding the evolutionary and physiological roles of Treh in insects.