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DNA Fingerprinting of Rice Varieties

DNA analysis, now a frequent courtroom evidence tool, is being fine-tuned by an Agricultural Research Service scientist as a faster way to develop and "fingerprint" new rice and wheat varieties to feed a hungry world.

"The world population is increasing at the rate of 96 to 100 million people each year—or nearly the size of another Mexico City every 12 weeks," says J. Perry Gustafson. He is a plant geneticist at Columbia, Missouri.

"We urgently need to improve cereal varieties by getting more genetic diversity into them," he says. "That's why finding and manipulating new specimens of food crops like wheat and rice is so important. Without being able to identify, increase, and use this diversity, the world could eventually run out of food."

Gustafson, working with University of Missouri graduate student Zongmin Zhou, from the People's Republic of China, recognized that humans share a 15-base-pair sequence of DNA with wheat, rice, and mice. Zhou used the knowledge to develop DNA fingerprint probes capable of distinguishing among rice and wheat varieties.

The researchers also used the common sequence to isolate others that produce a DNA fingerprint capable of both identifying and cataloging genetic differences within rice and wheat. They were the first in the world to use a single DNA sequence to distinguish between more than 80 rice varieties from the United States, the Philippines, and the China.

For plant breeders, DNA fingerprinting can be a quick way to select parents with the widest range of genetic variability.

Currently, breeders must use a "cocktail" of up to 40 RFLP (restriction fragment length polymorphism) probes in order to make the same selection for breeding. A single-fingerprint probe such as this one has the potential to cut several years off development of new rice and wheat varieties. -- By Linda Cooke.

Perry Gustafson is in the USDA-ARS Plant Genetics Research Unit, University of Missouri, 204 Curtis Hall, Columbia, MO 65211; phone (573) 882-7318.