Tomorrow afternoon, the fruits of several years of research will finally come to rest in SUNY College of Environmental Science and Forestry (ESF) soil. During the Annual Meeting of the New York State Chapter of the American Chestnut Foundation, several transgenic chestnut trees will be planted in holes around the entrance to the ESF Moon Library. These chestnut trees have been genetically modified to be resistant to Cryphonectria parasitica, a fungus commonly called chestnut blight. This devastating disease has caused a mass extinction of the once plentiful chestnut tree from its historic range in the eastern United States. The first genetically altered chestnut embryo cultures were produced on the spring of 2004 by William A Powell, an ESF faculty member. Powell continued research, producing potted plants in 2005 and beginning trials in spring of 2006.
Sam Tourtellot, a graduate student working in an ESF lab that receives funding from Powell's program, explained how the transgenic process works. “Scientists locate or create genes that produce a certain protein that produce compounds to inhibit the spread of the disease within plant tissues. Several other genes are used, including a synthetic protein that attacks the fungus directly, as an active defense mechanism that targets many different bacteria and fungi. These genes are implanted in the chestnut cells and then grown out over time.” The chestnut trees being planted are the Darling 4 variant, which contains oxalate oxidase, the protein to inhibit spreading the fungal infection.
So far, transgenic chestnuts have had moderate success in resisting the disease. Though they are not immune to the fungus, the transgenic chestnuts slow the spread of chestnut blight significantly compared to control groups.
The chestnut blight was accidentally introduced to North America around 1900, either through imported chestnut lumber or through imported chestnut trees. Powell traces the disease's path across the States: “It is thought that the original start point was New York City, and the disease quickly spread through trade routes out of that center of commerce. Within about 50 years the American chestnut was reduced from its predominant role in the forest as a keystone species to an understory shrub struggling to survive. The reason American chestnuts still survive today is due to their ability to resprout from their root collar. Unfortunately, the chestnut blight usually kills the tree back to the ground before it matures.”
The American Chestnut Foundation (ACF) is an organization working on reintroducing the American chestnut to the eastern woodlands. Most of the foundation's work involves crossbreeding the American species with the Chinese species, which is immune to chestnut blight. The New York chapter of the ACF is the only chapter involved in transgenic research, making the effort at ESF unique. It has also been creating dividends. On April 18th, a group of 10 transgenic chestnuts were planted at the New York Botanical Garden in the Bronx, at the place where it is thought that the disease was introduced. Hopefully this marks the beginning of the American chestnut growing back in places all across America.