Identification of a fatty acid synthase gene (FAS1) from Laodelphax striatellus planthoppers contributing to fecundity.

Fatty acid synthase (FAS) is a multifunctional enzyme that plays an important role in the formation of fatty acids. The fatty acids take part in many processes such as cell signaling and energy metabolism, and in insects they are important in cuticular hydrocarbon (CHC) formation and in reproduction. Here we characterized the sequence structure and function of a fatty acid synthase from the small brown planthopper (SBPH), Laodelphax striatellus. The full-length open reading frame (ORF) sequence of LsFAS1 was 7122 bp, encoding a predicted protein of 2373 amino acid residues. There were 7 functional domains in the LsFAS1 protein sequence. Gene expression screening by real-time quantitative PCR (RT-qPCR) showed that LsFAS1 was expressed in all developmental stages. Relative expression was highest at the 4 th -instar and female adult stages. For different tissues, the expression level of LsFAS1 in the ovary was the highest. Phylogenetic analysis showed that LsFAS1 clustered in a clade with two FASs from Nilaparvata lugens. Furthermore, these three FASs are related to cockroach BgFAS and locust LmFAS. After RNA interference-mediated knockdown, most treated insects died at eclosion. In addition, the life span of dsFAS1 treated female adults was shorter than that of the dsGFP injected control, and offspring production decreased. Also, the expression of vitellogenin (Vg) and vitellogenin receptor (VgR) genes decreased. Virgin females dissected at days 2 and 4 post eclosion showed many matured oocytes in planthoppers treated with dsGFP but not dsFAS1. These data highlight the importance of LsFAS1 in SBPH including a role in reproduction. This article is protected by copyright. All rights reserved.