The American chestnut, Castenea dentata, once one of the most common trees in the USA, was all but wiped out by 1950 from an introduced fungal blight. A new project wants to use GMO chestnut trees to bring it back.
American chestnuts were devastated by the accidental importation of an Asian bark fungus on specimens of the Asiatic chestnut, Castenea mollissima, back in 1904. Since then the disease has wiped out chestnut stands from most of southern and eastern USA, with only a few pockets of remnant trees in areas of greater climate extremes.
Attempts to interbreed the naturally resistant Asian chestnut with its American cousin have not produced worthwhile results so the American Chestnut Foundation has funded GMO research to insert the right kind of blight-resistant gene.
The Asiatic bark fungus, Cryphonectria parasitica, causes tissue damage through a build up of oxalic acid that the American chestnut is unable to break down. Researchers at SUNY College of Environmental Science and Forestry found that by inserting a gene from a plant that can break down oxalic acid, like wheat, it can give the chestnut the necessary tools to fight off the infection.
The gene was inserted using the DNA of an Agrobacterium that infects plants. When chestnut seedlings were inoculated with the bacterium, it expressed the modified DNA. From an initial trial group of transgenic ‘Darling4’ seedlings in 2010, the researchers have found increased blight resistance and that the tree is also able to pass on this resistance to the next generation.
But is America ready for a mass planting of genetically modified chestnuts?
Analysis of the chestnuts produced by the GMO trees show that they are chemically identical to those from non-GMO stock. However stringent food and safety guidelines in the USA will require the new chestnut to win approval from the USDA, the FDA and the EPA before there’s any field planting.
But how will the America public react? Will it welcome the restoration of such an iconic tree? Or reject it as a ‘Frankenstein’? Although rigorous scientific research is yet to find any bad effects from consuming GMO food, there’s been lots of negative feeling about GMO crops over the past decade. While much of this is more about abhorrence at the idea of multinational GMO companies like Monsanto controlling food crops, there’s also a strong rejection of ‘unnatural’ plants that carry genes from outside their natural hybrid range.
The American Chestnut Foundation may find it difficult to win over hearts and minds and it is also well-advanced with a more ‘natural’ alternative, a backcross hybrid between Castenea dentata and Castenea mollissima which is genetically 15/16ths American chestnut. Certainly planting GMO chestnuts in national parks and wilderness areas will be fiercely debated. But what of individuals and their home gardens?