AMES, Iowa — An investigation into a bur oak blight in central Iowa has resulted in three Iowa State University scientists being immortalized through scientific names for the previously unknown disease-causing fungi.
Thomas Harrington, a professor of plant pathology and microbiology, and Doug McNew, a mycologist and his longtime lab technician, identified three new species of a fungus called Tubakia. They added the fungi‘s names to the scientific nomenclature in honor of three former Iowa State colleagues.
The new fungus species are:
- Tubakia hallii, named for forest geneticist Richard B. Hall
- Tubakia tiffanyae, named for mycologist Lois H. Tiffany
- Tubakia macnabbii, named for forest pathologist H. Sande McNabb
The road to discovery started more than 10 years ago with an investigation of bur oak disease initiated by McNabb.
“Sande McNabb brought to my attention that his son’s neighborhood in West Des Moines was seeing some dramatic leaf disease,” Harrington said. “We eventually determined it was caused by undescribed species of fungus.”
Harrington and McNew called the newly discovered disease “bur oak blight,” BOB for short, and named the fungus Tubakia iowensis because it appeared to be native to Iowa.
“As we worked on bur oak blight, we found other related species of fungus on other species of oak tree in other circumstances,” he said. “We described those as new species, too, and we named them after our colleagues.”
Harrington said two decades of climate change has created wetter springs and better conditions for fungal infection and disease in Iowa. That made the species, which had likely been around for a long time, finally noticeable to scientists.
Species naming protocol
Harrington said the only rule for naming a new species is it must be Latinized. Often, discovering scientists choose names that are descriptive of the organism. But when discoveries don’t have unique characteristics to inspire a name, scientists can choose any name they like.
To become official, the name and a detailed description must be published in a peer-reviewed scholarly journal. There also must be a representative specimen of the species available. In this case, specimens of the three new Tubakia species are in the Iowa State herbarium. Once the name clears peer review and is published, it’s official.
Harrington said the naming process usually takes about a year. The three new fungi were published in Antonie van Leeuwenhoek Journal of Microbiology in late 2017.
International expert and “fun guy”
Harrington is an internationally recognized expert in the fungal genus Ceratocystis, which includes the oak wilt fungus. Most of his work has been outside Iowa, including in other countries.
He said being a mycologist — an expert on fungi — draws varying reactions from people. “Some kind of laugh. We get the ‘I bet you’re a fun guy,’ those kinds of jokes a lot.”
Harrington chose to focus on fungi because although they are pretty small, they are surprisingly complex.
“They fill interesting ecological niches, and some of them are quite economically important,” Harrington said. “So it’s good to do basic research on things that have potentially major economic and ecological importance.”
One of the critical roles fungi play in ecology is helping decompose dead plant and animals. An example of an economic benefit is the microscopic fungus yeast, which powers the production of ethyl alcohol used in beverages and as fuel.
Understanding leads to management
While the species of fungi Harrington and McNew discovered are rarely lethal to trees, they can weaken the plant so that insects or other diseases can cause major damage or even death. Forest pathologists are often on the forefront of battles against high-profile pathogens such as Dutch elm disease, which McNabb worked on during his time at Iowa State, or lethal pests like the emerald ash borer.
“The ultimate goal of the research is to see if diseases can be managed,” Harrington said. “One of the important things to do is to delineate what’s causing each disease. Fungal species are often difficult to discern from one another because they have pretty reduced structure. We have to use genetic analysis to tell one from another. Ultimately, we hope we can find a way to manage the diseases.”
Richard “Rick” Hall
Hall graduated from Iowa State University with a bachelor’s degree in forestry management in 1969. After earning a doctorate in plant breeding/plant genetics from the University of Wisconsin, Madison, he joined the ISU faculty in 1974. An avid outdoorsman, Hall was enthusiastic about his research as well as about teaching and leading many undergraduate students at the several Forestry Camps during his 42 years at Iowa State. His internationally known poplar research program earned him Society of American Foresters Fellow in 2014 in recognition of his contributions to genetic improvements in poplars for the bioenergy industry. He died in 2016 at the age of 69.
Known as “Iowa’s mushroom lady,” Tiffany earned a bachelor’s degree in botany and master’s and doctorate degrees in mycology, all from Iowa State. She joined the ISU faculty in 1950 and taught at the university until 2004. She won numerous awards, both in recognition of her teaching and as a pioneer for women in the sciences. Her special area of research was Iowa's prairie fungi. An Iowan truffle species — Mattirolomyces tiffanyae — was named in honor of her work with Iowa truffles. She died in 2009 at age 85.
Harold “Sande” McNabb Jr.
A graduate of the University of Nebraska, McNabb earned his master’s and doctorate degrees in forest pathology/plant physiology from Yale University. He joined the Iowa State faculty in 1953 where his work included research on Dutch elm disease, oak wilt and the development of hybrid poplar trees. McNabb won numerous awards for excellence in science and teaching and championed the accomplishments and legacy of fellow ISU scientist, George Washington Carver. He also advocated for opportunities in the sciences for minority students. McNabb died in 2011 at age 83.