Transcriptional comparison between pheromone gland-ovipositor and tarsi in the corn earworm Helicoverpa zea

Authors: DOU, X - Iowa State University; LIU, S - Iowa State University; AHN, SEUNG-JOON - Oregon State University; Choi, Man-Yeon; JURENKA, R - Iowa State University

Submitted to: Comparative Biochemistry and Physiology, Part D: Genomics and Proteomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2019
Publication Date: 6/25/2019
Citation: Dou, X., Liu, S., Ahn, S., Choi, M.Y., Jurenka, R. 2019. Transcriptional comparison between pheromone gland-ovipositor and tarsi in the corn earworm Helicoverpa zea. Comparative Biochemistry and Physiology, Part D: Genomics and Proteomics. 31:100604. https://doi.org/10.1016/j.cbd.2019.100604.
DOI: https://doi.org/10.1016/j.cbd.2019.100604

Interpretive Summary: Insect moths are major pests of agriculture worldwide, and their control is responsible for the largest use of chemical pesticides. As a chemical alternative, insect pheromones are becoming more popular because they are environmently-friendly control tools to protect many agricultural crops and animals. Of the insect moths, the corn earworm (Helicoverpa zea) is the most important agricultural pest. Major and minor pheromone components of the moth have been identified from their female pheromone glands, and are currently being utilized for controlling those pests. Scientists, from USDA-ARS, Oregon State University, and Iowa State University previously found a large amount of saturated fatty acid derivative 16:Ald in the male legs. In this study, we identified a variety of enzymes and receptors involved in signal transduction and pheromone transportation using RNA sequencing technology. The research results showed that there were many genes differentially expressed between tissues. Therefore, we discovered how these genes are involved in the biosynthesis of 16:Ald in the tarsi and pheromone glands of the insect. Additionally, the possible role of proteins in chemosensation and oviposition in the moth may provide a clue to improved pheromone application.

Technical Abstract: The corn earworm, Helicoverpa zea, utilizes Z11-16:Ald as the major sex pheromone component. The saturated fatty acid derivative 16:Ald is also found in the pheromone gland and recently a large amount (0.5-1.5 µg) was found in male tarsi with lower amounts (0.05-0.5 µg) in female tarsi. In this study, we compared the transcriptome between female pheromone glands (including the ovipositor) and female and male tarsi to identify differences between these tissues, particularly the genes involved in sex pheromone biosynthesis and in chemosensation. We found 11 fatty acyl desaturases (DESs), 20 fatty acyl-CoA reductases (FARs), 7 alcohol dehydrogenases (ACDs), some GPCRs and many genes involved in signal transduction and pheromone transportation. Also we found gustatory and olfactory receptors associated with the tarsi and ovipositor. Differential expression analysis showed that there were many genes differentially expressed between tissues, including the candidate DESs, FARs, ACDs. We discuss how some of these genes produce proteins that could be involved in the biosynthesis of 16:Ald in tarsi and Z11-16:Ald in the pheromone gland and the possible role of proteins in chemosensation of the tarsi and ovipositor.