Journal Article

Knockdown of the Expression of Two Trehalase Genes with RNAi Disrupts the Trehalose and Chitin Metabolism Pathways in the Oriental Armyworm, IMythimna separata/I

Dai, Changchun, Fan, Dong, Zhang, Xinxin, Zhang, Weijia, Wang, Sibo, Yang, Hongjia, Zhao, Xiaohui, Wang, Yixiao, Cui, Mengyao

2024

Overview

Trehalose is the most important carbohydrate in insects. It is required for chitin synthesis and, thus, insect growth and development. Trehalase is the only enzyme that catalyzes the decomposition of trehalose. Mythimna separata is an important pest of cereal crops. We cloned and identified Tre1 and Tre2 cDNA sequences in M. separata. Analysis of MsTre1 and MsTre2 expression revealed that MsTre1 was highly expressed in the midgut, and MsTre2 was highly expressed in the integument. The expression of MsTre1 and MsTre2 was the highest in the pupal stage. We used RNA interference to inhibit MsTre1 and MsTre2 expression. MsTre1 and MsTre2 silencing resulted in significant changes in the expression of genes associated with trehalose and chitin metabolism, and significantly reduced the MsTre1 and MsTre2 activity and the glucose and chitin content. Hematoxylin and eosin staining, and transmission electron microscopy showed that the silencing of MsTre1 slowed larval molting, and the new cuticle was significantly thinner in dsMsTre1-injected larvae than in control larvae. Overall, MsTre1 and MsTre2 are two effective genes in M. separata that regulate insect growth via the trehalose and chitin metabolism pathways, and MsTre1 is more important for cuticle formation in the epidermis than MsTre2. Trehalose is an important carbohydrate substance in insect hemolymph. Chitin is the main component of cuticle and peritrophic matrix in insects. Trehalase (Tre) catalyzes the decomposition of trehalose. Few studies of trehalase in lepidopteran insects have been conducted. Here, the functions of soluble Tre (Tre1) and membrane-bound Tre (Tre2) in the growth and development of Mythimna separata were investigated. We cloned and identified Tre1 and Tre2 cDNA sequences in M. separata. Analysis expression revealed that MsTre1 and MsTre2 were highly expressed in midgut and integument, respectively. The expression of MsTre1 and MsTre2 was highest in the pupal stage. We used RNA interference (RNAi) to inhibit Tre expression in M. separata larvae. Injection of dsMsTre1 or dsMsTre2 resulted in abnormal phenotypes and impeded normal molting. Silencing of MsTre1 and MsTre2 resulted in significant changes in the expression of genes in the trehalose and chitin metabolism pathways, significantly increased the trehalose and glycogen content, and significantly decreased MsTre1 and MsTre2 activity, the glucose content, and the chitin content in midgut and integument. Silencing of MsTre1 slowed larval molting, and the new cuticle was significantly thinner. These results indicate that RNAi of Tre may be useful for control strategies against M. separata.

• Publisher: MDPI AG
• Subject: Army-worms / Genetic aspects