Fatty acid elongase gene SfELO1 is essential for maintaining the cuticular lipid barrier and antifungal defense in Sogatella furcifera

The cuticular lipid layer is critical for preventing desiccation and pathogen invasion in insects. Its biosynthesis is mediated by fatty acid elongases (ELOs); however, the specific ELOs involved in this process in the rice pest Sogatella furcifera, as well as their roles in defense, remain unclear. Fifteen ELO genes were identified and characterised based on transcriptomic and genomic sequences of S. furcifera. Expression profiles across different tissues were determined using RT-qPCR, revealing that six SfELO genes were highly expressed in the integument. Among these, SfELO1, SfELO6, and SfELO14 were also strongly induced upon infection by Beauveria bassiana. Functional analysis showed that silencing SfELO1 increased susceptibility to fungal infection. Furthermore, knockdown of SfELO1 disrupted cuticular lipid homeostasis, resulting in reduced cuticular hydrocarbon and fatty acid contents, thinning of the lipid layer, and impaired hydrophobicity and permeability. These findings demonstrate that SfELO1 is essential for maintaining cuticular barrier integrity and antifungal defense against B. bassiana in S. furcifera, highlighting it as a promising target for improving the efficacy of entomopathogenic fungi in pest management.