PxTret1-mediated trehalose transport regulates development and reproduction in Plutella xylostella with implications...

Trehalose transporter 1 (TRET1) plays a key role in insect trehalose homeostasis and abiotic stress adaptation. However, its role in insecticide susceptibility remains largely unexplored, particularly to Bacillus thuringiensis toxins. In Plutella xylostella, we found that PxTret1 is post-transcriptionally regulated by pxy-miR-8522. Furthermore, PxTret1 was significantly upregulated following Cry1Ac protoxin exposure, while pxy-miR-8522 was downregulated. Dual-luciferase assay confirmed that pxy-miR-8522 recognizes PxTret1. Overexpression of pxy-miR-8522 markedly downregulated the expression of PxTret1 in vivo and increased the larval mortality by 22% at 36 h after Cry1Ac treatment. Similar results were observed in larvae subjected to PxTret1 RNA interference, with mortality rising by 20% at 48 h after Cry1Ac exposure. Furthermore, these treatments impaired larval development and perturbed trehalose and glucose homeostasis. Overexpression of pxy-miR-8522 and RNAi treatment significantly decreased pupation rates by 36.11% and 54.36%, respectively. Transcriptomic analysis of these RNAi-treated larvae demonstrated that knockdown of PxTret1 dysregulates genes associated with chitin binding involved in maintaining peritrophic membrane stability, which can potentially lead to bacterial translocation from gut into hemolymph, eliciting subsequent immune responses. Moreover, knockdown of PxTret1 in pupae by overexpression of pxy-miR-8522 or RNAi severely compromised adult fitness, including shortened lifespan, wing deformities, and reduced fecundity. The adult abnormal rates of both groups were nearly twice those of the control. This work identifies PxTret1 as a molecular target with dual potential: enhancing Cry1Ac efficacy and suppressing pest fitness. By linking trehalose transport, chitin metabolism, and immune regulation, it advances our understanding of insect physiological networks and provides a foundation for developing RNAi-based or chemistry-driven strategies for sustainable pest management in cruciferous crops.