Molecular cloning and temporal-spatial expression profiling of trehalose-6-phosphate synthase gene in Spodoptera frugiperda (Lepidoptera: Noctuidae) and its response to temperature stress.
Aim: This study aims to clone SfTPS gene from the fall armyworm, Spodoptera frugiperda, and to analyze its relative expression levels in different developmental stages, different tissues and the 5th instar larvae under different temperature stresses, so as to lay the foundation for further exploring the function of TPS in the growth and development of S. frugiperda and its anti-stress response. Methods: The full-length coding region of S. frugiperdaSfTPS was cloned by RT-PCR technology and analyzed by bioinformatics. The relative expression levels of SfTPS in different developmental stages (egg, 1st-6th instar larva, pupa, and adult), different tissues of the 5th instar larva (integument, midgut, and fat body), and the 5th instar larvae of S. frugiperda subjected to short-term (2, 4 and 8 h) high temperature (35°C) and low temperature (10°C) stress were detected by RT-qPCR technology. Results: The cDNA sequence of TPS gene of 2 571 bp was cloned from S. frugiperda and named SfTPS (GenBank accession number: MT920672). Its open reading frame (ORF) is 2 481 bp in length, encoding 826 amino acids with two conserved domains (TPS and TPP). Homologous comparison and phylogenetic analysis showed that TPS proteins in insects are highly conservative. SfTPS has the closest relationship with TPS of S. litura, showing 99.15% amino acid sequence identity. The proportions of α-helix, β-sheet and random coil in SfTPS are 38.14%, 12.23%, and 48.55%, respectively. The tertiary structure of SfTPS is homo-dimer. The RT-qPCR results showed that SfTPS was lowly expressed in the egg and 1st-5th instar larval stages of S. frugiperda, and highly expressed in the 6th instar larval, pupal and adult stages. Moreover, the relative expression level of SfTPS changed greatly before and after the metamorphosis of S. frugiperda. The tissue distribution results showed that SfTPS had the highest expression level in the fat body of the 5th instar larvae of S. frugiperda. After the 5th instar larvae of S. frugiperda were subjected to low temperature (10°C) and high temperature (35°C) stress for 2-8 h, the relative expression levels of SfTPS were significantly higher than that of the control (25°C), being 4.43-9.34- and 2.50-6.03-fold as high as that of the control, respectively. Conclusion: SfTPS gene might play important roles in the growth and development, and resisting high and low temperature stress in S. frugiperda.