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UCR Research Project Explores How Plant Virus Spreads

UCR Research Project Explores How Plant Virus Spreads

(January 5, 2000)

A University of California, Riverside plant scientist has been awarded a $225,000 federal grant to examine how a plant virus interacts with its host plant to cause disease. A.L.N. Rao, associate professor of plant pathology, received a three-year research grant from the U.S. Department of Agriculture to study at the molecular level how plant viruses "assemble" during the infection process. Knowledge gained in the study could point to new methods of controlling plant diseases in economically important crops.

Specifically, Rao will examine an RNA (ribonucleic acid) virus called brome mosaic virus (BMV), which infects barley and wheat. An outbreak of brome mosaic virus is currently occurring in the midwestern United States, but the virus does not cause significant crop losses. However, the virus is genetically nearly identical to cucumber mosaic virus, which affects several economically important California crops such as tomatoes, carrots, celery, bell peppers and cucumbers.

Plant viruses use various mechanisms to replicate and spread from cell to cell. Earlier studies by Rao have found that the brome mosaic virus exhibits a unique interaction between its RNA and its coat protein - an essential step in the infection process.

"We are studying how these viruses get 'packaged' because packaging of viral RNA by coat protein to make virus particles is an important event in the infection process," said Rao, who has studied genetic and biochemical properties of BMV since 1993 and is the co-author of numerous articles on molecular aspects of the virus in international journals.

Rao's investigations have revealed that altering the coat protein changed the pathology of the virus. Certain mutant coat proteins bind well to the viral RNA and form stable particles that spread infection throughout a plant. Other mutant coat proteins, however, do not package viral RNA well and the viruses are unable to cause a full-scale infection.

"By understanding RNA-coat protein interactions, it will be possible to devise novel methods of virus disease control in economically important crops," Rao said.

This new research project, aimed at better understanding the molecular basis of this model virus, will also involve collaboration with scientists at the Scripps Institute in San Diego. State-of-the-art laboratory technology there will allow researchers t o determine the structural features of the coat protein, which might be related to packaging of viral particles and subsequent infection of a plant.

"My research is likely to understand how viruses assemble during infection. If we can prevent the assembly, then we can control virus infections in plants," he said.

Intriguingly, the coat protein of brome mosaic virus has some similarities to that of HIV, the virus that causes AIDS. Rao plans future research to explore the functional similarities between the two viruses.

The University of California, Riverside ( is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion.

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