The article, “Genome-Enabled Insights into the Biology of Thrips as Crop Pests,” is published in the journal BMC Biology. It is the work of 57 scientists on five continents.
“This project represents over eight years of work by at least 17 laboratories across the globe,” said Professor Ullman, a former chair of the entomology department and a fellow of the Entomological Society of America and the American Association for the Advancement of Science. Her laboratory worked closely with project leader and first author Dorith Rotenberg of North Carolina State University. Project scientist Sulley Ben-Mahmoud of the Ullman lab is the paper's third author.
The western flower thrips, Frankliniella occidentalis, causes billions of dollars a year in damage worldwide. Native to Western North America and about the size of a pinhead, the insect feeds on a wide array of food, fiber, and ornamental crops and transmits plant viruses that cause significant economic damage.
“The western flower thrips and the viruses it transmits, including tomato spotted wilt virus, is important to California agriculture, causing serious problems for tomato growers, pepper growers and growers of leafy greens,” Ullman said. The tomato spotted wilt virus infects more than 1000 plant species, ranging from tomatoes, tobacco and peanuts to pansies and chrysanthemums.
“This system has been a central element of my research program for over 30 years," Ullman said, "and I am extremely excited to see this important resource made available as a tool to help us understand and control these important pests.”
In their abstract, the authors wrote that the publication should lead to “understanding the underlying genetic mechanisms of the processes governing thrips pest and vector biology, feeding behaviors, ecology, and insecticide resistance.”
“Attaining a tool to unlock the mysteries of western flower thrips biology and interactions with plant viruses in the family Tospoviridae has been a dream of mine through over 30 years of working on this system,” Ullman commented. “The genome project enabled the discovery of salivary gland-enriched genes in this tiny insect that is now guiding work that Sulley Ben-Mahmoud and I are doing with collaborators Dorith Rotenberg, Joshua Benoit, Samuel Bailey and Priya Rajarapu to identify salivary proteins acting as effectors.”
Rotenberg launched the project in 2011 after delivering a lecture at the 5th Annual Arthropod Genomics Symposium in Kansas City, Mo. “At the time, I was very naïve about what it would take to steward a thrips genome project, but was excited about what a genome sequence could mean for those of us interested in the molecular basis of thrips vector competence and thrips pest biology.”
The team worked with the i5k initiative, an international effort to sequence and analyze 5,000 arthropod genomes. This includes insects, crustaceans, spiders and other creatures with exoskeletons, segmented bodies and pairs of jointed legs.
The Rotenberg-led thrips genome project team first developed an inbred line of thrips. Baylor College of Medicine's Human Genome Sequencing Center sequenced and assembled the genome. The Rotenberg team then verified the location of 10 percent of the nearly 17,000 genes and annotated them to better understand what they do.
The authors report that some genes are associated with the thrips' ability to develop and reproduce, to find plant hosts through taste and smell, to protect against pathogens, and to detoxify plant-produced chemicals and insecticides. The latter is of special interest because thrips are known for rapidly building up resistance to chemicals.
Said Rotenberg: “I discovered over the course of eight years that the thrips genome consortium created something much greater than the sum of its parts. I was fortunate to recruit 17 international groups with expertise in arthropod genomics, evolution and development, thrips vector biology and microbe (and virus)-insect interactions to volunteer their time not only to manually correcting and annotating gene models, but to use expression evidence to explore with me new frontiers in thrips innate immunity, lateral gene transfers of bacterial origin, thrips-plant interactions, thrips development and reproduction. These world-renowned experts helped shape the landscape for contemporary molecular and evolutionary studies of Thysanoptera and in my opinion, as important, helped shape the careers of several undergraduates, grad students and postdoctoral scholars involved in the process. I am excited and proud of what we accomplished together.”
Ben-Mahmoud described the research as “a monumental feat, and I am proud of my contributions to it. I have no doubt that the paper will inform and benefit the studies of many other international insect-vector research groups, not only those who work directly with the western flower thrips.”