Effect of four chitinase genes on the female fecundity in Sogatella furcifera (Horváth).

Background: The white-backed planthopper (WPH), Sogatella furcifera (Horváth), is a destructive rice pest with strong reproductive capacity. To gain insights into the roles of chitinases in the reproductive process of this insect species, this study represents the first-ever endeavor to conduct an in-depth exploration into the reproductive functions of four chitinase genes.

Results: In this study, it was observed that four chitinase genes were expressed in female adults, with a relatively high expression level in the ovaries. SfCht2 and SfIDGF1 were highly expressed during later ovarian development. while SfENGase increased and then decreased with ovarian development. SfCht2, SfCht6-2 and SfENGase were highly expressed in fat body on the first and second days after eclosion, whereas SfIDGF1 highest on day 7. Compared with control group, Silencing four chitinase genes inhibited ovarian development and significantly shortened the oviposition period of S. furcifera, reducing egg-laying capacity but not affecting egg hatching. The detection demonstrated that the expression levels of SfVg, SfVgR and 70-90% juvenile hormone (JH) signaling pathway-related reproductive genes was significantly down-regulated. Moreover, SfCht6-2 and SfENGase significantly affected the expression levels of Target of Rapamycin (TOR) signaling pathway genes. SfENGase had the ability to impact nutrient signaling pathways and fatty acid metabolism, repressing vitellogenin synthesis and ultimately influencing ovarian development of S. furcifera.

Conclusions: Overall, this study provides insight into the function of chitinases in insect fecundity and is of great significance for enriching the cognition of insect chitinase function. They will become the suitable target genes for controlling the most destructive rice planthoppers. © 2023 Society of Chemical Industry.