USDA grant advancing deadly plant disease, insect research

January 23rd, 2013
A competitive grant is helping a Kansas State University doctoral student turn the insect responsible for spreading one of the worst plant diseases into a tool that stifles the disease's transmission.

Ismael E. Badillo-Vargas, a plant pathology doctoral student, Puerto Rico, recently was awarded a predoctoral fellowship grant of more than $71,000 from the U.S. Department of Agriculture's National Institute of Food and Agriculture. The competitive scholarship is awarded to agriculture students who have two more years to complete their doctoral degree programs. Recipients receive two years of funding for research expenditures, tuition, a graduate research salary and conference travel.

For Badillo-Vargas, the fellowship advances his research on the tomato spotted wilt virus and its relationship to thrips—tiny, winged insects that carry and spread the plant disease.

Tomato spotted wilt virus is one of the 10 most devastating plant viruses, according to the USDA. The virus, which kills a variety of food-producing plants, causes about $100 million in U.S. crop losses and roughly $1 billion in global crop losses every year.

The virus is transmitted to plants by the western flower thrips. The virus, however, does not harm the thrips that carry it and replicate the virus. Badillo-Vargas wants to understand why.

He is looking at how the tomato spotted wilt virus affects thrips at the molecular level. Badillo-Vargas is identifying which of the insect's proteins interact with the virus. In doing so, he and other researchers can target these proteins with genetic techniques that could turn off the insect's immunity to the virus.

"The idea is that this may keep the insect from being able to spread the virus anymore," Badillo-Vargas said. "It could stop the insect from being able to carry the tomato spotted wilt virus or even kill the insect with the virus because its defense system would be gone. Ultimately it would let us control the spread of the virus and also the insect itself, which is an agricultural pest and disease vector."

Badillo-Vargas is developing a RNA interference, or RNAi—a short sequence of genetic information that could knock down the insect's protective genes. The RNAi could be delivered through a spray that only affects thrips or possibly even delivered to thrips by the plants themselves.

Badillo-Vargas is using a partial transcriptome of the thrip's genes that was produced by Dorith Rotenberg, research assistant professor of plant pathology. The transcriptome is a scientific tool that acts as a reference catalog for certain genes in the thrips. Rotenberg is working to sequence the thrip's genome, which will be a complete genetic blueprint of the insect and all of its genes.

"With the partial transcriptome I'm starting to look at certain genes that I believe can be silenced with RNAi because they have a potential interaction between the virus and the insect," Badillo-Vargas said. "Some of these molecules were able to be silenced in other insects when RNAi tools were used on them. In some cases it even killed the insect."

The research will build on a study by Badillo-Vargas that was published in the August 2012 edition of the Journal of Virology. It compared the differential proteins expressed by healthy thrips with those from thrips infected with the tomato spotted wilt virus. It showed that thrips have an early response to the virus infection and when the virus is the most active.

"I was thrilled to learn that Ismael had received this fellowship," said Anna Whitfield, associate professor of plant pathology and Badillo-Vargas' major adviser. "It's very competitive and many people apply, but very few are selected. It's a wonderful fellowship that will benefit Ismael professionally and advance research on tomato spotted wilt virus and thrips."

Provided by Kansas State University

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