Abstract: 【Aim】 Trehalose-6-phosphate synthase (TPS) is one of the main enzymes in regulating trehalose levels in the insect haemolymph. This study aims to clone and characterize the TPS genes in Blattella germanica and to profile their expression patterns in extreme temperature environments. 【Methods】 The full-length cDNA sequences of two TPS genes were cloned using RACE technology, and their relative expression levels in different tissues of the 5th instar larvae and under cold (exposed to 10℃ and 0℃ for 1 h, respectively) and heat stress (exposed to 40℃ and 46℃ for 30 min, respectively) were measured using the real-time quantitative PCR (qRT-PCR) technique. 【Results】 The full-length cDNAs oftwo TPS genes were cloned from B. germanica, and named BgTPS1 and BgTPS2, respectively. BgTPS1 (GenBank accession no.: KR050213) is 2 987 bp in length and has an open reading frame (ORF) of 2 502 bp, encoding a protein of 833 amino acids. BgTPS2 (GenBank accession no.: KR050214) is 3 212 bp in length and has an ORF of 2 469 bp, encoding a protein of 822 amino acids. The qRT-PCR analysis revealed that BgTPS1 and BgTPS2 mRNA were mainly expressed in the fat body of the 5th instar larvae, with the level of BgTPS2 mRNA 3.9-fold as high as that of BgTPS1. Under the extreme temperature induction, the expression levels of BgTPS1 and BgTPS2 increased, and the level of BgTPS2 mRNA was much higher than that of BgTPS1 under all stress conditions. The expression levels of both TPS genes were much higher under cold induction (0℃) than under other temperature induction. 【Conclusion】 The two TPS genes were highly expressed in the fat body of the 5th instar larvae of B. germanica, and the level of BgTPS2 mRNA was much higher than that of BgTPS1. The expression levels of BgTPS1 and BgTPS2 increased under both cold and heat stresses. The results provide a foundation for the further research of TPS genes and their roles in the regulation of temperature acclimation in insects.

Key words: Blattella germanica, trehalose-6-phosphate synthase, gene cloning, temperature induction, mRNA expression level