Expression Profiles of the Trehalose-6-Phosphate Synthase Gene Associated With Thermal Stress in Ostrinia furnacalis (Lepidoptera: Crambidae)

Trehalose is the major blood sugar in insects. Physiological significance of this compound has been extensively reported. Trehalose-6-phosphate synthase (TPS) is an important enzyme in the trehalose biosynthesis pathway. Full-length cDNAs of TPS (Oftps) and its alternative splicing isoform (Oftps_isoformI) were cloned from the Asian corn borer (ACB), Ostrinia furnacalis (Guenee; Lepidoptera: Crambidae) larvae. The Of tps and Oftps_isoformI transcripts were 2913 and 1689 bp long, contained 2529 and 1293 bp open reading frames encoding proteins of 842 and 430 amino acids with a molecular mass of 94.4 and 48.6 kDa, respectively. Transcriptional profiling and response to thermal stress of Of tps gene were determined by quantitative real-time PCR showing that the Of tps was predominantly expressed in the larval fat body, significantly enhanced during molting and transformation; and thermal stress also induced Of tps expression. Gene structure analysis is indicating that one TPS domain and one trehalose-6-phosphate phosphatase (TPP) domain were located at the N- and C-termini of Of TPS, respectively, while only the TPS domain was detected in OfTPS_isoformI. Three-dimensional modeling and heterologous expression were developed to predict the putative functions of OfTPS and OfTPS_isoformI. We infer that the expression of Of tps gene is thermally induced and might be crucial for larvae survival.