Geneticist collaborates on finding a solution to an industry killing citrus crop disease Meet Douglas Stuehler

To Douglas S. Stuehler Jr., doctors have always been superheroes. As a child, he became curious about medicine and wanted to understand everything there is to know about the work doctors do. In high school, Stuehler was introduced to chemistry, where his interest in medicine naturally evolved into a deep curiosity of molecular biology and genetics. He earned an associate’s degree in science with honors from Elgin Community College and then a bachelor’s in molecular and cellular biology with a minor in chemistry from the University of Illinois Urbana-Champaign.

Stuehler discovered his passion for genomics during an internship at Fort Pierce, and he later joined the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) Research Participation Program to continue his growth as a geneticist. “It is a great chance to develop my skills and research a broad array of organisms and environments using state-of-the-art technologies,” said Stuehler.

The USDA ARS Research Participation Program provides opportunities for students, postgraduates, established scientists and faculty to participate in programs, projects and activities at ARS-designated facilities to help ARS solve agricultural problems of high national priority.

Initially under the mentorship of Wayne Hunter, Ph.D., and now Michelle Heck, Ph.D., Stuehler is collaboratively researching a disease that afflicts citrus crops called Huanglongbing (HLB). HLB is caused by bacteria that is spread by the Asian citrus psyllid (Diaphorina citri, or D.citri for short), a small insect no bigger than the tip of a pencil. D. citri. and the bacteria has created great damage to the citrus industry and agriculture, nearly causing the collapse of the market in Florida.

Led by Heck and in collaboration with Marina Mann, Stuehler is using genome-wide association to discover the genes within D. citri that allow it to acquire the bacteria. The goal is to make it so the insect cannot propagate the bacteria, and therefore cannot transfer it into citrus crops. Another part of the study is a collaboration to develop a new plant biotechnology, called a symbiont, in hopes of finding a cure to HLB in affected citrus plants.

Another of Stuehler’s research projects moves from citrus crops and D. citri, to the oceans. Here, the team is characterizing an antibody called immunoglobulin new antigen receptors (IgNARs) in Atlantic and Southern stingrays. A small part of the IgNAR antibody contains a potentially useful protein called variable new antigen receptor (VNAR). VNAR helps the stingrays protect themselves against foreign pathogens by inhibiting their functionality. The USDA hopes that VNAR is a promising protein to be extracted and used in plants to help them fight pathogens in much the same way.

“My research will impact society by accelerating studies aimed at creating a world of sustainable agriculture,” said Stuehler. “Through helping to create and support a world where nutritious foods are readily available, all agricultural research supports the health of every individual.”

The research is featured in the Journal of Invertebrate Pathology and BioRxiv, and there are plans to submit a co-authored paper on their D. citri genome-wide association study. Additionally, Stuehler presented two posters on the study, one at the 2^nd Congress of the International Society for Citrus Huanglongbing and Phloem-Colonizing Bacterial Pathosystems Conference in Florida, and the second at the 12^th International Congress of Plant Pathology in France.

While Stuehler's typical day includes analyzing data for biological trends, he says his favorite experience is meeting diverse scientists who are at all different stages of their careers. He enjoys hearing their unique perspectives and expressed gratitude for the influence his mentor Heck has had on his research.

“She has allowed me to grow as a research scientist, and the experience I have gained in her laboratory will last a lifetime. I am extremely impressed with my experience,” said Stuehler.

“I definitely recommend the Oak Ridge Institute for Science and Education’s (ORISE) programs to any scientist who is eager to learn and make a difference. My USDA-ARS ORISE appointment has allowed me to grow as a scientist and really showcase my curiosity and enjoyment of research. I feel I could not have started my career off any better than where I currently am .”

Stuehler has big plans for after he completes his fellowship with USDA-ARS. As a child he was fascinated with doctors, and he hopes to continue his love for medicine by translating his current research into personalized human medicine through genetics. He plans to earn his doctoral degree in either computational biology or plant pathology.

The USDA ARS Research Participation Program is funded by USDA and is administered through the U.S. Department of Energy’s (DOE) Oak Ridge Institute for Science and Education (ORISE). ORISE is managed for DOE by ORAU.