The TGF-beta receptor gene Saxophone influences larval-pupal-adult development in Tribolium castaneum

Authors: LI, JINGJING - University Of Missouri; YIN, LETONG - University Of Missouri; BI, JINGXIU - University Of Missouri; Stanley, David; FENG, QILI - South China Normal University; SONG, QISHENG - University Of Missouri

Submitted to: Molecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2022
Publication Date: 9/15/2022
Citation: Li, J., Yin, L., Bi, J., Stanley, D.W., Feng, Q., Song, Q. 2022. The TGF-beta receptor gene Saxophone influences larval-pupal-adult development in Tribolium castaneum. Molecules. 27(18). Article 6017. https://doi.org/10.3390/molecules27186017.
DOI: https://doi.org/10.3390/molecules27186017

Interpretive Summary: Some insect species are serious pests of agriculture. In the U.S., invasive species cause approximately $70 billion in crop damage. Although agricultural industries create improved chemical insecticides, environmental damage and insect resistance to insecticides are major, on-going problems. At the global level, many scientists are working to develop effective alternatives to chemical insecticides, most recently inventing genetic tools to manage pest insects. The problem that detailed information on genes that are vital to insect development is generally lacking. In this paper, we report on detailed analysis of a specific gene that is necessary for insect development. After blocking expression of the gene, we found test insects died before they completed development to adulthood. Scientists around the world will use this new information to develop genetic pest insect management technologies. When fully developed, these new technologies will contribute to abundantly available healthful foods for a growing human population.

Technical Abstract: The transforming growth factor-ß (TGF-ß) superfamily encodes a large group of proteins, including TGF-ß isoforms, bone morphogenetic proteins and activins that act through conserved cell-surface receptors and signaling co-receptors. TGF-ß signaling in insects controls physiological events, including growth, development, diapause, caste determination and metamorphosis. In this study, we used the red flour beetle, Tribolium castaneum, as a model species to investigate the role of the type I TGF-ß receptor Saxophone (Sax) in mediating development. Developmental and tissue-specific expression profiles indicated Sax is constitutively expressed during development with lower expression in 19- and 20-day (6th instar) larvae. RNAi knockdown of Sax in 19-day larvae prolonged developmental duration from larvae to pupae and significantly decreased pupation and adult eclosion in a dose-dependent manner. At 50 ng dsSax/larva, Sax knockdown led to 84.4% pupation rate and 46.3% adult emergence rate. At 100 ng and 200 ng dsSax/larva doses, pupation was down to 75.6% and 50%, respectively, with 0% adult emergence following treatments with both doses. These phenotypes were similar to those following knock down of 20-hydroxyecdysone (20E) receptor genes, EcR or USP. Expression of 20E biosynthesis genes Disembodied and Spookier, 20E receptor genes EcR and USP, and 20E downstream genes BrC and E75, were suppressed after Sax knockdown. Topical application of 20E on larvae treated with dsSax partially rescued the dsSax-driven defects. We infer that the TGF-ß receptor gene Sax influences larval-pupal-adult development via 20E signaling in T. castaneum.