Scientists have sequenced the genome of the tobacco hornworm, or Manduca sexta, a caterpillar species that can be a pest to gardeners.
It eats the leaves of tomato plants and also can be found on pepper, eggplant, and potato plants. Crops and weeds from this plant family, which includes tobacco, produce chemicals such as nicotine that deter feeding by most insects, but not M. sexta, which makes its physiology especially interesting to scientists.
“This project represents years of collaborative research across the world.”
The name Manduca comes from the Latin word for glutton because these caterpillars eat so much. M. sexta occurs naturally in North, Central, and South America.
“The completion of this project marks a major milestone in the study of insect biochemistry and molecular biology, as Manduca sexta is an important model insect: one that has been studied for its physiology and biochemistry for many decades,” says Gary Blissard of the Boyce Thompson Institute located at Cornell University.
“This project represents years of collaborative research across the world,” says Michael Kanost, a professor at Kansas State University. “We wanted to provide these valuable data to scientists, and our hope is that this sequenced genome will stimulate new research in molecular studies of insects.”
Blissard and Kanost are co-senior authors of a paper in the journal Insect Biochemistry and Molecular Biology. The project involved 114 scientists from 11 countries. They’ve made the genome available to the public through the National Agricultural Library and the National Center for Biotechnology Information.
Kanost has studied the tobacco hornworm for decades, and he and Blissard decided to start the collaborative project to sequence the tobacco hornworm’s genome in 2009. Collaboratively, the research team sequenced the DNA that encodes the genes as well as the RNA from the insect at different developmental stages, to identify when different genes are expressed and in which tissues and organs.
Kanost and the Kansas State University team prepared and purified the DNA of the tobacco hornworm and sent the samples to the Baylor College of Medicine Human Genome Sequencing Center in Houston, which performed the genome sequencing.
Blissard’s group isolated RNA from a broad range of tissues and specific developmental stages throughout the egg, larval, pupal, and adult stages of the insect. The international team used a common computer system so that researchers from around the world could analyze the gene sequences based on their areas of expertise.
Blissard studies the interactions between viruses and their insect hosts. He and his colleagues examined the vacuolar protein sorting (VPS) genes. These genes code for proteins involved in transporting small containers called vesicles throughout the healthy cell, but these proteins are often hijacked by viruses in order to move the virus through the cell.
“What makes the project unique is that so many different groups did in depth studies of so many gene families,” says Blissard “and this is an exceptionally rich resource that will be useful not only to scientists studying insects, but also to scientists studying other organisms and their pathogens and diseases.”
The National Institutes of Health and the Defense Advanced Research Projects Agency, or DARPA, funded the project.
Source: Jennifer Tidball and Patricia Waldron for Boyce Thompson Institute/Cornell University