In their prime, American chestnut trees stood 100 feet tall and 6 feet wide. Now, they’re typically no bigger than shrubs, thanks to a fungal disease that spread down the East Coast decades ago, virtually wiping out the hardwood tree.
But researchers in UGA’s Warnell School of Forestry and Natural Resources, with support from ArborGen LLC, a leader in tree improvement and commercial production of trees, have developed a method for inserting anti-fungal genes into the tree’s DNA. They hope the new genes will fight off the fungal disease and help restore the American chestnut to its former glory.
The results of Scott Merkle’s 20-year effort are detailed in a new paper published in the journal Plant Cell Reports, where he and associates Gisele Andrade and Joe Nairn describe the system they developed to insert new genes into the tree’s DNA and to propagate trees that carry the genes.
“The gene transfer system described in the new paper already has been used to produce some trees with genes that may conferresistance to the fungal disease,” said Merkle, “and ultimately could be used to help restore the tree to our eastern forests.”
Merkle and his team of research associates and graduate students have been studying ways to get the chestnut trees to fight off the fungus. The disease works by attacking the chestnut after the bark has been injured, fanning out and killing the inner bark layer, eventually girdling the tree so that food and water cannot move up or down the stem.
After years of research, Merkle and Andrade devised a way to grow chestnut trees from single cells and found an effective way to separate the genetically engineered cells from the cells that did not have the inserted genes. Now, they’ve used their system to insert an anti-fungal gene, obtained from collaborator William Powell at SUNY College of Environmental Science and Forestry, into chestnut trees that are being grown in a Warnell greenhouse in preparation for testing the ability of that inserted gene to fight off the fungus.
The way they’ll do that, Merkle said, is by infecting the tree with the fungus and measuring how well it fights it off. It’ll be at least two years before they can take that next step in the research, however, since the trees have to grow to a certain size before they can be screened.
“It’s been a real challenge working with it,” he said. “But the potential is there.”