Molecular cloning and expression analysis of soluble and membrane-bound trehalase genes in the cotton bollworm, Helicoverpa armigera

Trehalase plays a significant role in various physiological processes in insects. In this study, we cloned and characterized a soluble trehalase gene (HaTreh-1) and a membrane-bound trehalase gene (HaTreh-2) from Helicoverpa armigera, a serious polyphagous pest of crops. HaTreh-1 contained an open reading frame of 1716. bp that encodes a protein of 572 amino acids. HaTreh-2 has an open reading frame of 1938. bp, encoding a protein of 646 amino acids. Sequence alignment and phylogenetic analysis of the two putative proteins revealed that HaTreh-1 and HaTreh-2 belong to soluble and membrane-bound trehalase groups, respectively. Quantitative real-time PCR (qPCR) analyses of the spatiotemporal expression pattern of HaTreh in H. armigera revealed that HaTreh-1 was expressed mainly in the midgut, with lower expression in the integument and head, Malpighian tubules, trachea, and fat body. The expression levels of HaTreh-2 were detected in all 6 tissues, and HaTreh-2 was mainly expressed in the midgut and head. Expression of HaTreh-1 was higher throughout the larval stages, but lower on days 1 and 2 of the pupal stage. Expression of HaTreh-2 was higher during the 4th- and 5th-instar larval stages. Taken together, these results suggest that HaTreh-1 and HaTreh-2 have different functions in various developmental stages and tissues.