Abstract: Trehalose, which is the blood sugar in insects, is synthesized mainly by trehalose-6-phosphate synthase (TPS) in insects. By homologous cloning and rapid-amplification of cDNA ends (RACE), the full cDNA of the TPS gene in Harmonia axyridis was cloned and named HaTPS (GenBank accession number: FJ501960). This gene with 5′ and 3′ non-coding region of 26 bp and 505 bp, respectively, contains an open reading frame of 2 418 nucleotides encoding a protein of 805 amino acids with the predicted molecular weight of 90.58 kDa and pI of 7.01. The encoded protein contains two potential N-glycosylation sites, without signal peptide and transmembrane domain. The homology comparison showed that insect TPS was highly conserved with two conserved domains. Real-time fluorescent quantitative PCR was conducted at different developmental stages under the cold induction to detect the expression of HaTPS. The results showed the expression level of HaTPS was the highest in the pre-pupal stage. Under the condition of shortterm cold induction, the HaTPS expression was dramatically increased with temperature decreasing; and under the condition of warming and cooling, its expression level increased first, and then declined. The results suggest that TPS plays an important role in the regulation of insect resilience and its regulatory capacity is increased significantly under cold-induction.

Key words: Harmonia axyridis, trehalose-6-phosphate synthase (TPS), trehalose, cold induction, real-time fluorescent quantitative PCR