Viral-Induced Gene Silencing
Mick Held, Ph.D., a postdoctoral researcher in Dr. Carpita's lab, virologist Steve Scofield, Ph.D., a U.S. Department of Agriculture research scientist and adjunct assistant professor of agronomy at Purdue, and Dr. Carpita made the discovery in barley after introducing Barley Stripe Mosaic virus as a way to “silence” specific genes and study their functions. The researchers noticed that the virus had more effect than anticipated.
“The virus hijacked a whole suite of genes, and when we compared the targeted plant to our control plants we found that the small RNAs were responsible and already in the controls even without adding the virus,” explains Dr. Held.
Dr. Carpita says the finding allowed researchers to see that the siRNAs, among other things, regulate and shut down primary cell wall development to begin secondary wall growth. “These secondary stages result in characteristics such as tough rinds of corn stalks, vascular elements to conduct water, and fibers for strength,” he notes.
The researchers believe that delaying or preventing the shutdown of both primary and secondary cellulose production might enhance total plant biomass.
“Most biofuel researchers believe that cellulose utilization offers the best path to sustainable ethanol production,” says Dr. Scofield. “Our work uncovered a previously unknown mechanism that suggests a way to increase the amount of cellulose produced in plants.”