Hernan Garcia-Ruiz did not understand why the farmers could no longer grow the tomatoes and peppers and beans that had once fed their small town north of Mexico City. He was a child then, watching the farmers reluctantly abandon their favored crops for corn and wheat.
“Nobody had a clue about why the plants were dying,” Garcia-Ruiz said. “Eventually I learned that the plants got infected with viruses. I felt the pain of losing crops to viruses.”
Now an assistant professor of plant pathology, Garcia-Ruiz will work toward helping others avoid the same fate with the assistance of a $1.3 million grant from the National Institutes of Health. The five-year grant will help Garcia-Ruiz research how plants identify, target and silence the viral ribonucleic acid, or RNA, that worms its way into cells and allows a virus to replicate.
Garcia-Ruiz and other researchers have already identified certain genes that contribute to this RNA silencing, which can act as a defense mechanism that helps plants develop immunity against viruses. They also know that double-stranded viral RNA can trigger cells’ production of small interfering RNA, or siRNA – bits of ribonucleic acid that essentially slice viral RNA into harmless ribbons.
“Those small pieces move all over the plant, essentially as an alarm system that prepares the entire plant to fight viral infections, establishing a state of immunity,” said Garcia-Ruiz, a member of the Nebraska Center for Virology. “Once a single cell is able to recognize the virus, the defense system gets activated in the entire plant.”
What researchers don’t know – what Garcia-Ruiz wants to find out – are exactly what stages or features of viral replication activate the alarm system. He also hopes to ascertain how the siRNA distinguishes between the cellular RNA essential for healthy functioning and the viral RNA that can ultimately destroy the plant.
Doing so, he said, could accelerate efforts to engineer immunity in a wide range of crops and other plants.
“The commercial applications of this are multiple,” Garcia-Ruiz said. “Every single crop gets infected by at least one virus. For many of those crops, there are no sources of natural resistance. But once we know exactly how this immunity works, we can essentially design plants to activate their immune systems against any virus in any crop.”
Garcia-Ruiz will receive his funding from the National Institute of General Medical Sciences under grant no. R01-GM-120108.