Viruses Under the Microscope

A virus can replicate quickly within a living cell. Once that process starts, there’s really nothing you can do to prevent its replication within the host plant.

Dubbed the invisible foe by plant pathologists Rose C. Gergerich and Valerian V. Dolja,¹ viruses can pack a small but mighty punch. Viruses impact virtually all crops to some extent. One of the aspects that makes viruses difficult to identify and manage is their size. Viruses are the smallest of all known organisms, typically ranging from 5 to 300 nanometers in size. Specialized lab equipment is required to detect their presence and determine their identity.

“Because you don’t necessarily know what the virus is by looking at it through an electron microscope, you have to use other technologies, such as genome sequencing and polymerase chain reaction (PCR) or antibody detection methods, which can take months in some cases,” says Steven Whitham, Ph.D., professor of plant pathology and microbiology at Iowa State University.

Whitham works with colleagues who frequently visit Iowa soybean fields to find plants that are exhibiting abnormal, potentially yield-reducing symptoms. He determines if viruses are present and classifies them using advanced diagnostic technologies such as next-generation sequencing.

“As a plant pathologist, I always have to think about the pathogen, the hosts, the environment and how they interact with one another,” Whitham says. “It’s important to know which viruses are present and understand how these interactions continually change. A virus can replicate quickly within a living cell. Once that process starts, there’s really nothing you can do to prevent its replication within the host plant.”

¹Gergerich, R.C., and V. V. Dolja. 2006. Introduction to Plant Viruses, the Invisible Foe. The Plant Health Instructor. DOI: 10.1094/PHI-I-2006-0414-01