Location: Invasive Insect Biocontrol & Behavior LaboratoryTitle: Functional identification of fatty acyl reductases in female pheromone gland and tarsi of the corn earworm, Helicoverpa zea
|DOU, XIAOYI - Iowa State University|
|JURENKA, RUSSELL - Iowa State University|
Submitted to: Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2019
Publication Date: 11/1/2019
Citation: Dou, X., Zhang, A., Jurenka, R. 2019. Functional identification of fatty acyl reductases in female pheromone gland and tarsi of the corn earworm, Helicoverpa zea. Insect Biochemistry and Molecular Biology. https://doi.org/10.1016/j.ibmb.2019.103260.
Interpretive Summary: The corn earworm is a major pest in North America and has a wide host range. This moth migrates seasonally at night, and can be carried downwind up to 400 km. It is the greatest threat to sweet corn production and has become resistant to many pesticides. A female produced sex attractant has been identified for population monitoring and infestation detection. The common synthetic pathway of sex attractant has been widely studied in many similar moths, however, the alcohol oxidation enzyme, which catalyzes the last step of biosynthesis, has not been identified at the molecular level in any insect. In this study, we have functionally characterized four fatty acid reduction enzymes (FARs) from insect tarsi. This is the first study to demonstrate that the same FAR is involved in sex attractant biosynthesis, in specific sex attractant glands, and in sex attractant production in tarsi. This finding will help scientists understand the mechanisms regarding enzyme-catalyzed processes where substrates are converted into more complex products in living organisms.
Technical Abstract: Most moths utilize sex pheromones released by the female to attract a mate. Females produce the sex pheromone in the pheromone gland in a biosynthetic pathway which consists of several key enzymes. Fatty acyl-CoA reductase is one of the key enzymes, which catalyzes the conversion of fatty acyl-CoA to the corresponding alcohol, playing an important role in producing the final proportion of each pheromone component. In Helicoverpa zea, (Z)-11-hexadecenal is the major sex pheromone component in female pheromone glands and previously a large amount of hexadecanal was also found in female and male tarsi. In our previous study, we compared the transcriptome between pheromone glands and tarsi and found 20 fatty acyl-CoA reductases in both tissues. In this study, we functionally characterized four FARs which were expressed at high levels according to the transcriptome of pheromone glands and tarsi. Fatty acyl-CoA reductase 1 was homologous to other moth pheromone gland specific fatty acyl-CoA reductases, and it was also present in male tarsi. Functional expression in yeast cells indicates that only fatty acyl-CoA reductase 1 was able to produce fatty alcohols. In addition, a decreased mRNA level of fatty acyl-CoA reductase 1 in female pheromone glands and male tarsi by RNAi knockdown caused a significant decrease in the production of (Z)-11-hexadecenal in pheromone glands and hexadecanal in male tarsi. This study is the first to demonstrate the direct function of a fatty acyl-CoA reductase in male tarsi and also confirms its role in sex pheromone biosynthesis in H. zea.