Scientists seek to breed by stressing plants through epigenetics
By John O'Connell
ABERDEEN, Idaho -- An Idaho USDA agricultural researcher sees potential to breed desirable traits in crops by exposing them to stressful environments, based on a modern field of science that challenges traditional notions of genetics.
Victor Raboy, a research geneticist with the Agricultural Research Service in Aberdeen, has three ongoing experiments delving into how barley varieties can be affected by epigenetics -- the idea that the expression of heritable genetic traits can change without any alternations in an organism's genetic code.
"There's no question this also plays a role in agricultural traits. It just isn't well understood yet," Raboy said.
Raboy explained chemicals can silence or activate genes -- though the DNA alphabet is unchanged -- causing trait alterations offspring may inherit, and providing organisms another tool to adapt to changing environments. Those chemicals work more like a volume dial than a light switch, enabling researchers to manipulate trait expression by varying degrees.
"If you picture a field of corn plants in the wild, the original idea was some plant has a lucky mutation which confers more reproductive success. That happy mutation becomes widespread in the population. In epigenetics, the change doesn't happen in a single individual but is happening in the whole population."
Brett Tyler, director of Oregon State University's Center for Genome Research and Biocomputing, described epigenetics as chemical tags that "bookmark" DNA, indicating which genes plants should use. He said the tags can be inherited, but they can also change when a plant is under stress.
"This is how they enable plants to adapt, but it also makes it a bit uncertain whether varieties that were created using epigenetic variation would breed true," Tyler said.
One of Raboy's experiments, in its third year, involves planting 200 barley plants in a greenhouse with limited water, and replanting the best 10 plants, replicating the process through five generations. He hopes through epigenetics the plants will adjust themselves to be more drought tolerant.
Another experiment involves growing barley plants with low and moderate nitrogen and phosphorus doses to develop progeny requiring less fertilizer. He's in the process of analyzing data from his nutrient experiment and is optimistic he'll see an epigenetic shift, based on past successes of similar research.
His third ongoing epigenetics trial seeks to elevate and reduce phosphorus levels in barley seed by replanting seeds with high and low phosphorus content.
Ohio State University molecular geneticist Jay Hollick has used epigenetics to manipulate the color of a purple corn variety first documented decades ago at a Nebraska state fair.
Though epigenetics occurs in nature and shouldn't raise the hackles of opponents of genetically modified crops, Hollick said his research has also shown epigenetic approaches could prevent transgenic changes from spontaneously turning off in biotech crops.
Regarding epigenetics in crop breeding, Hollick predicts it will take several years for epigenetics to become common in crop breeding.
"It's going to take probably a decade more, but certainly it will become more mainstream," he said.
OSU barley breeder Pat Hayes said epigenetics has been "huge in human medicine," but he'll wait until applications for plant breeding are better understood before using the science in his lab.
"I try to stay attuned to the field because it's just explosive," Hayes said.