White oak genome reveals genetic markers for climate adaptation and pest resistance

White oak (Crix alba) is economically, ecologically and culturally important. However, the species currently faces a significant challenge: a low rate of seedling recruitment, the process by which seeds successfully germinate and grow into new trees.

“Environmental stresses such as drought and disease, as well as plant competition from native and non-native plants, make it increasingly difficult for young white oaks to establish themselves,” says Meg Staten, associate professor of bioinformatics and computational genomics in the Department of Entomology and Plant Pathology.

Recent advances by Staton and colleagues have opened up new avenues of investigation. For the first time, they have sequenced the complete genome of the white oak, providing insight into its genetic structure and evolution. The breakthrough will increase understanding of variation within species, helping researchers identify and exploit traits such as pest resistance and climate adaptation that can improve seedling survival.

“Decoding the genome is a monumental advance, the next step is identifying which genetic markers are important for sustainability in challenging environments,” Staten explained. “By identifying these traits, we can support our forest ecosystems by developing new species that are more resilient.”

In Tennessee and much of eastern North America, many organisms depend on white oaks, including mammals, birds, insects, and fungi. In addition to playing a key role in biodiversity, soil health and carbon sequestration, white oak is also a highly valued hardwood used in products such as whiskey barrels at the famous Jack Daniel’s Distillery in Lynchburg, Tennessee.

Staten led the research with Drew Larson at Indiana University in collaboration with the University of Kentucky, the US Forest Service, the University of Tennessee, and others. However, their recent progress is just one example of how Utia is advancing forest sustainability.

Another Margaret Finley Shackford Orchard Complex was established in 2001 by the Margaret Finley Shackford Charitable Trust, the Hobart Ames Foundation, the Ames Agricultural and Education Center in Grand Junction, Tennessee, and the UT Tree Improvement Program. Dedicated to the development of seed orchards for twenty-one species of trees, primarily oak, the complex spans over a hundred acres in the Ames Center. Across a range of lowland and upland areas, researchers are experimenting with healthy forestry that enhances both ecological stability and timber production, including testing plants from a mix of species within existing ecosystems.

“We highly feature oak trees in small forest openings and leave them to fight an explosion of herbivore and tree competition,” says Allan Houston, a research professor in the School of Natural Resources.

“Traditional silviculture predicted absolute failure, but some species, such as cherrybark oak, are very competitive. Many of the trees planted thrive to supplement mature stands, which contain no oaks. Currently, we have thousands of trees in these experiments, where the ultimate goal is not to sow seeds in other areas.”

Houston, along with Scott Schlerbaum, professor and director of the UT Tree Improvement Program, coordinated the projects at the Shackford Orchard Complex. Collected seeds are ready for the Tennessee Division of Forestry’s East Tennessee State Nursery in Delano, Tennessee, except for small amounts for research. Although valuable data have been collected for about two dozen species, three have shown exceptional success: white oak, water oak, and the highly competitive cherrybark oak.

These hardwoods are valued not only for wood products but also for their important roles in local ecosystems. Genetic research on white oaks first began at the Ames Center in 1973, with a white oak seed orchard established in 1998 and a second generation test in 2001. Orchards of other species, such as the Chickasaw plum, started as recently as 2017, with genotypes still being added to increase genetic diversity in the orchard. However, a seed orchard developed for cherrybark oak already exists, and is expected to be collected for nursery production in the coming years.

“Sustainable forestry depends on how we manage our resources in a shrinking land base available for forests and a growing human population,” says Schlerbaum. “Utia’s achievements in DNA sequencing, seed orchard development, and health forestry experiments will enrich forest ecosystems and ensure their vitality for generations to come.”