Knickkopf (LmKnk) is required for chitin organization in the foregut of Locusta migratoria

Abstract

The foregut, located at the front of the digestive tract, serves a vital role in insects by storing and grinding food into small particles. The innermost layer of the foregut known as the chitinous intima, comes into direct contact with the food and acts as a protective barrier against abrasive particles. Knickkopf (Knk) is required for chitin organization in the chitinous exoskeleton, tracheae and wings. Despite its significance, little is known about the biological function of Knk in the foregut. In this study, we found that LmKnk was stably expressed in the foregut, and highly expressed before molting in Locusta migratoria. To ascertain the biological function of LmKnk in the foregut, we synthesized specific double‐stranded LmKnk (dsLmKnk) and injected it into locusts. Our findings showed a significant decrease in the foregut size, along with reduced food intake and accumulation of residues in the foregut after dsLmKnk injection. Morphological observations revealed that newly formed intima became thinner and lacked chitin lamella. Furthermore, fluorescence immunohistochemistry revealed that LmKnk was located in the apical region of new intima and epithelial cells. Taken together, this study provides insights into the biological function of LmKnk in the foregut, and identifies the potential target gene for exploring biological pest management strategies.

Tissue-specific alternative splicing and the functional differentiation of LmLPMO15-1 in Locusta migratoria

“…Chitin is well known as an essential structure component of the exoskeletons (Yu et al, 2016;Noh et al, 2018;Qu et al, 2022a;Long et al, 2023), the wings (Xu et al, 2020), the peritrophic membrane of the midgut (Liu et al, 2012;Qu et al, 2022b), the intestinal lining of foregut (Zhang et al, 2021;Yu et al, 2024) and hindgut (Zhang et al, 2021), the taenidia of trachea (Yu et al, 2016;Qu et al, 2022a), as well as in the lumen of salivary glands (De Giorgio et al, 2023). It protects insects from various damages present in their living environment, such as chemical attacks, physical wear and tear, and pathogen invasion (Merzendorfer & Zimoch., 2003;Muthukrishnan et al, 2012;Zhu et al, 2016).…”