LmCHS1 mediates pro-nymphal cuticle formation in Locusta migratoria embryogenesis

Abstract

The pro-nymphal cuticle, serving as a protective structure that facilitates environmental adaptation, is critical for insect embryonic development. However, the mechanisms governing its formation remain poorly understood. In this study, we investigated the important role of chitin synthase (LmCHS1) in the formation of the pro-nymphal cuticle during embryonic development in Locusta migratoria. The pro-nymphal cuticle begins to form in 8-day-old embryos (E8) and undergoes degradation by E12, coinciding with the preparatory phase (E13-E14) for hatching of the first-instar nymph. Spatiotemporal expression analysis indicated that LmCHS1 mRNA levels are elevated before cuticle formation, with protein localization peaking at the plasma membrane during active chitin synthesis (E8-E11). Targeting LmCHS1 through embryonic RNA interference (RNAi) resulted in developmental failures during late embryogenesis. Additionally, ultrastructural analysis confirmed that silencing LmCHS1 disrupts the normal chitin structure in the pro-nymphal cuticle. Further investigation into the ecological function of LmCHS1 in adapting the pro-nymphal cuticle to dry environments revealed that the tolerance of embryo to various dry conditions is significantly reduced after konckdown of LmCHS1. In summary, these findings highlight the essential role of chitin synthase in the formation of the pro-nymphal cuticle in locust embryos, underscoring its importance in embryonic development and adaptation to environmental challenges like desiccation.