Scientists from Harvard University have teamed up with seed company Monsanto to apply a new technique that may help solve one of the direst problems in agriculture: the emergence of pests that are resistant to genetically-engineered crops.
Thanks to Harvard professor David Liu's phage-assisted continuous evolution (PACE) technology, Harvard and Monsanto scientists evolved new forms of a protein known as "Bt toxin," which can assist in controlling Bt toxin-resistance in insects. Bt stands for Bacillus thuringiensis.
With typical processes, it can take a year to engineer the insect-killing protein in a laboratory, but using the PACE technology, it can take only a month, said Thomas Malvar, lead of the insect-control discovery at Monsanto.
Liu, who is the corresponding author of the study, said their goal in the collaboration with Monsanto was quite ambitious.
The team wanted to find answers to the following questions: can a Bt toxin be retargeted to a different insect gut protein by evolving the protein itself? Will doing so allow them to kill the Bt toxin-resistant pests?
"Our hope was to use PACE to help stay ahead of insect resistance," said Liu.
And they did. With this breakthrough, Liu and his team advanced new Bt toxins that contained dozens of amino acid alterations over 500 generations in just 22 days of PACE.
Theoretically, using PACE means being able to tweak the protein into remaining deadly. This can be done faster than the pace at which insects become resistant to genetically-modified (GMO) crops.
GMO crops such as soybeans and corn have become less effective in the recent years as weeds and pests develop resistance to insecticides and herbicides.
The team's work could potentially boost the efficacy of Monsanto seeds, which also contain Bt, but Liu said their work only scratched the surface.
As the collection of proteins, evolved with the help of PACE, become more diverse, Liu said he hopes scientists will continue to use PACE to take on problems that are difficult to solve through traditional methods. In fact, if it took PACE 22 days to pull off 500 generations, traditional stepwise methods might take a decade.
PACE could also be used in a variety of fields that would benefit from the quick evolution of proteins. For instance, in health care, PACE could speed up the discovery of new therapeutic proteins, researchers said.
In the meantime though, the new technique would likely apply first commercially in corn and cotton, they added.
The study is published in the journal Nature on April 27.
Photo : James Almond | Flickr
