Abstract:

Objective: This study aims to analyze the function of the rapamycin target protein gene (DaTOR) in Dendroctonus armandi, and elucidate its regulatory role in energy metabolism under starvation, heat stress, and cold stress, so as to provide new insights into metabolism-targeted control strategies against D. armandi. Method: The full-length sequence of DaTOR gene was obtained through gene cloning. Quantitative real-time PCR was used to determine its spatiotemporal expression patterns and assess expression changes under starvation and temperature stresses. RNA interference was applied to investigate the role of DaTOR in regulating lipid and carbohydrate metabolism under different stresses, as well as its contribution to survival under starvation, heat stress, and cold stress. Result: 1) The amino acid sequence encoded by DaTOR contained conserved TOR domains and shared 96.57% similarity with that encoded by DpTOR from Dendroctonus ponderosae. 2) The expression level of DaTOR in D. armandi was the highest in pupae and emerged female adults, the lowest in larvae, and highest in fat bodies among different tissues. 3) Under starvation and cold stress, DaTOR expression showed a progressive down-regulation with increasing stress duration. Under heat stress, DaTOR expression increased transiently, reaching its peak at 12 h, and then declined. 4) RNA interference of DaTOR in larvae and adult males and females of D. armandi resulted in a significant reduction in DaTOR transcript levels. Under starvation and heat stress, post-interference mortality in larvae exceeded that in adult males and females, reaching 73.33% and 71.67%, respectively. Under cold stress, adult males exhibited the highest mortality rate, reaching 76.67%. 5) After injection of dsTOR, the contents of triacylglycerol, glycogen and trehalose in female adults, male adults and larvae of D. armandi showed a decreasing trend, while the content of free fatty acids showed an increasing trend under starvation, heat and cold stresses. Conclusion: DaTOR exhibits differential expression across developmental stages and tissues of D. armandi, and displays distinct response patterns under starvation, heat stress, and cold stress. RNAi-mediated knockdown alters energy metabolism, confirming the involvement of DaTOR in regulating energy homeostasis under these stresses.

Key words: Dendroctonus armandi, target protein of rapamycin, starvation and temperature stresses, RNA interference, energy metabolism