Working to Create a Blight-Tolerant Ozark Chinquapin

 

Patrícia Morais Fernandes, a postdoctoral researcher with ESF’s Tree Restoration Center, is attempting to develop a blight tolerant Ozark chinquapin (Castanea ozarkensis). The tree is a long-lost cousin of the American chestnut (Castanea dentata), and both species are fighting functional extinction caused by blight.

Beginning in 1989, ESF professors Bill Powell and Charles Maynard worked to develop a blight-tolerant American chestnut using genetic engineering. Their work and legacy live on in ESF’s Tree Restoration Center following their passing. Today, the ESF transgenic chestnut tree (Darling 54) awaits approval by U.S. regulatory agencies, with the eventual goal of introduction into natural forest ecosystems.

Fernandes is applying the American chestnut work to the Ozark chinquapin. “The next logical step is to apply all this knowledge that was developed for the American chestnut to closely related species that are also endangered by the same pathogen,” says Fernandes. “Adapting three decades of work is saving us a lot of time.”

The Ozark chinquapin is native to the Ozark region of Missouri, Arkansas, and Oklahoma. Before the blight hit, a healthy chinquapin stood up to 65 feet tall. Like the American chestnut, it provided rot-resistant wood and nutritious nuts, while its pollen and leaves nurtured myriad insects. Nowadays a few individuals survive as bushes, which are unable to develop to maturity and hence are unable to reproduce.  

Fernandes has been working on this project since October 2021. A native of Portugal, she did her PhD at the Nova University of Lisbon, studying the interactions between European and Japanese chestnuts and ink disease. She won a Fulbright scholarship to work for five months with Powell on the American chestnut. “That was the first time I worked with genetic transformation. After the five months were up, I went back to Portugal, where I got an email from Dr. Powell offering a postdoc position after I finished my PhD thesis. I was very excited because I loved working here. This team is amazing,” says Fernandes.   

That team is taking two approaches to creating a blight-tolerant Ozark chinquapin: direct genetic transformation, which consists of inserting a blight-resistance gene into the tree’s genome, and backcross breeding, pollinating an Ozark chinquapin with pollen from the transgenic blight-tolerant American chestnut.  Says Fernandes, “The backcross breeding approach gave us transgenic trees that are half American chestnut and half Ozark chinquapin. The idea is to use the pollen produced by those hybrids to pollinate Ozark chinquapins, then repeatedly backcrossing until we get a tree with the resistance gene that’s fifteen-sixteenths Ozark chinquapin. At that point, we’ll plant it and see if they develop like a normal chinquapin and lost the American chestnut’s characteristics.” Four years into the project, the team is studying several transgenic Ozark chinquapins developed through genetic transformation. They’ve also harvested the first nuts, which may soon serve as the parents of the final backcross needed to produce a predominantly Ozark chinquapin transgenic tree. 

Fernandes’ work on the Ozark chinquapin is funded almost exclusively through philanthropic donations, and she has a continued need for funding to keep researching the understudied tree. “Funding means we’re one step closer to restoring the species. Short term, I’m hoping to develop a blight-tolerant tree and then test restoration strategies.”  

 

“I also want to do more fundamental science, understanding the interaction between the Ozark chinquapin and blight. We don’t know the genetics or the crosstalk. I’d really like to get funding for grad students, because that’s another thing that funding means to me: passing along our knowledge to younger generations.”