Separate research teams have reported two significant discoveries in the use of genetic engineering to enhance crop plants, advances that could eventually have far-reaching significance in feeding a burgeoning world population. In the first study, published in the Proceedings of the National Academy of Sciences, researchers from Spain and Germany created vitamin-fortified corn enhanced with three key nutrients. Although genetic modification has been used to enhance the vitamin content of several crops including rice, potatoes, and tomatoes, this is the first time scientists have been able to increase multiple vitamins in a single plant.

The genetically modified African corn has 169 times the normal amount of beta carotene, a precursor of vitamin A; six times the amount of vitamin C; and two times the amount of folate. The high level of beta carotene was possible because scientists are more familiar with the genes that control that nutrient.

 

The research was led by Paul Christou of the University of Lleida in Spain. He and his team targeted this combination of vitamins because deficiencies in them cause many diseases in the developing world. They used a South African white corn variety and inserted five genes from other organisms by attaching them to microscopic gold particles and shooting them into immature corn embryos in a laboratory dish. When the cells divided, they contained the new genes. The genes have stayed intact over four generations so far, according to the study. The new fortified corn has bright yellow kernels and is just a proof of concept, according to the researchers.

 

In the second study, published online by Nature, researchers at the University of Minnesota and Massachusetts General Hospital have used a genome engineering tool they developed to make a model crop plant herbicide-resistant without significant changes to its DNA. The new approach has the potential to help scientists modify plants for specific purposes while minimizing concerns about genetically modified organisms.

 

“It’s still a GMO but the modification was subtle,” says Daniel Voytas, lead author and director of the U of M Center for Genome Engineering. “We made a slight change in the sequence of the plant’s own DNA rather than adding foreign DNA.”

 

Current methods for introducing a desired trait involve inserting a gene with the desired trait from another organism into the organism that is being modified. In the study, researchers created a customized enzyme called a zinc finger nuclease to change single genes in tobacco plant cells. The altered cells were then cultured to produce mature plants that survived exposure to herbicides. The study was co-authored by J. Keith Joung, a pathologist at Massachusetts General Hospital and an associate professor at Harvard University.

 

“This is the first real advance in technology to genetically modify plants since foreign DNA was introduced into plant chromosomes in the early 1980s,” Voytas says. “It could become a revolutionary tool for manipulating plant, animal and human genomes.”

 

Zinc finger nucleases are engineered enzymes that bind to specific DNA sequences and introduce modifications at or near the binding site. The standard way to genetically modify an organism is to introduce foreign genes into a genome without knowing where they will be incorporated. The random nature of the standard method has given rise to concerns about potential health and environmental hazards of genetically modified organisms.

 

According to Voytas, the zinc finger nucleases technology created by his lab can be used to improve the nutrition of crop plants, make plants more amenable to conversion into biofuels, and help plants adapt to climate change. His next step will be to apply the technology to Arabidopsis thaliana, a standard research plant, and rice, the world's most important food crop. He is also using it to modify algae for biofuel production.