USDA, Pioneer Hi-Bred to Automate Screening for Crops' Viral Resistance

A new instrument that helps breeders screen for resistance to important viral diseases of corn and soybean is being refined and automated in a cooperative research effort by the Agricultural Research Service and Pioneer Hi-Bred International, Inc., of Johnston, Iowa.

Former ARS scientist Ray Louie developed the technique, called Vascular Puncture Inoculation (VPI). He's a retired ARS plant pathologist who continues to work as a research collaborator at the ARS Corn and Soybean Research Unit in Wooster, Ohio. He and ARS technician John Abt have been working with the technique since 1991.

The ARS unit at Wooster, led by Roy Gingery, together with Ohio State University colleagues at the Ohio Agricultural Research and Development Center campus where the unit is located, specialize in detecting and preventing viral attacks on corn and soybeans.

The team receives samples of infected corn leaves from around the world and soybean leaves from throughout the region for viral identification. Most samples are too small to do much more than a few tests. With VPI, the team can produce enough infected plants to more fully characterize the virus, and all without even knowing which insect transmits the virus in nature.

This "artificial insect" technique uses an instrument to infect plant seeds with a virus, much as an insect does when it bites into a leaf. The instrument's tiny vibrating pins "bite" water-softened seeds to introduce a liquid viral extract previously prepared by grinding infected leaves. Louie is working to automate the instrument so that it can quickly infect entire trays of seeds.

A microprocessor-controlled advanced prototype uses pins attached to a stereo speaker-like component to produce vibrations of controlled frequency and intensity

With VPI, they have been able to transfer all major corn viruses into kernels of corn and have also transferred viruses into soybean seeds, wheat kernels, and rice grains. Then they grow infected plants from the seeds.

ARS is the U.S. Department of Agriculture's chief scientific research agency.