Sphingolipid composition and metabolism differ in three auchenorrhynchous pests of rice

Sphingolipids (SPLs), a group of membrane and intracellular lipids, mediate numerous cellular processes. The composition and metabolism of sphingolipids varies according to species and the sphingolipid studies of insects, as compared to mammals, are not yet clear. In the current study, we subjected three auchenorrhynchous insects, including whitebacked planthopper (WBPH), Sogatella furcifera, small brown planthopper (SBPH), Laodelphax striatellus, and green rice leafhopper (GRLH), Nephotettix cincticeps, as representative rice pests for sphingolipid analysis. We performed sphingolipid species profiling using UPLC-Q-TOF-MS/MS and isolated sphingolipid metabolic genes from their transcriptomic data. C14-, C16-, C18- and C20-sphingoid base were detected in both planthoppers, but no C14- sphingoid base was found in GRLH. The planthoppers had more abundant sphingosine-1-phosphates (Sph-1-P) and ceramides than leafhopper. A total of 14, 13 and 16 sphingomyelin species were found in SBPH, WBPH and GRLH, respectively. The composition of sphingomyelin species varied in three insects. Coordinated with the abundance in sphingomyelin species, the leafhopper possessed more sphingomyelinase (SMase) gene isoforms for metabolism of different sphingomyelins than planthoppers. The phylogenetic analysis showed the three tested insects all possessed one potential neutral-SMase homologue, whereas SBPH and GRLH both had another potential acid-SMase homologue. This study is a comprehensive sphingolipidomic analysis, suggesting that sphingolipid profiles significantly differed among the three insects. By providing information of sphingolipid metabolic gene homologues of these three insects, our findings will contribute to the further sphingolipid studies of auchenorrhynchous insects and provide a research foundation for rice pest management.