Abstract:Trehalose-6-phosphate synthase (TPS) is a key enzyme in trehalose synthesis and plays an important role in the response of organisms to stress. In this study, based on the unigene sequences from transcriptome sequencing of Litopenaeus vannamei challenged with high-temperature stress, the partial TPS cDNA sequence (complete ORF and partial UTR) (LvTPS) was obtained directly by PCR amplification. Sequence analysis revealed that the LvTPS sequence contained a 2529 bp open reading frame, encoding 842 amino acids with a molecular weight of 95.4 kDa and an isoelectric point of 6.17. LvTPS had two functional domains, the Glyco-transf-20 domain and the Trehalose_PPase domain. Multiple sequence alignments showed that LvTPS had the highest homology with the corresponding gene in Fenneropenaeus chinensis, with a similarity value of 63.73%. The phylogenetic tree indicated that LvTPS was closely related to that of F. chinensis, and clustered with invertebrates, such as Callinectes sapidus, Exopalaemon carinicauda, and Procambarus clarkia. Vertebrates were clustered onto a signal branch. Quantitative analysis of gene expression levels showed that LvTPS was widely expressed in all of the examined tissues with different expression levels. The gill and muscle had similar levels and the highest expression. The expression of the eye stalk, heart, and nerve was next, being significantly lower than that of gill and muscle (P<0.05). The expression in the hepatopancreas was the lowest, being significantly lower than that of the other five tissues (P<0.05). L. vannamei kept at 26℃ were used as control group. When the temperature was increased to 32℃, the LvTPS gene in the eye stalk and heart was significantly increased (P<0.05). When the temperature was increased to 38℃, the expression of the LvTPS gene significantly rose in gill, hepatopancreas, eye stalk, and heart (P<0.05). Expression in the hepatopancreas was significantly changed. Thereafter, the expression of the LvTPS gene decreased when the temperature decreased. When the temperature was returned to 32℃ and 26℃, the expression of the LvTPS gene in the six tissues was not significantly different from that of the control group. There was no significant difference in expression under different levels of temperature stress in the nerve and muscle. The above results indicated that LvTPS was closely related to the response to high-temperature stress. This study provided basic data for the analysis of the mechanism of the response to high-temperature stress in L. vannamei.
