Blight Resistance in Genetically Engineered Rice

Cloned Rice Gene May Help Control Devastating Blight
Release Date:
Doris Brody, NIGMS

In a few years, rice farmers around the world may see significantly higher yields, thanks to genetic engineering made possible by NIGMS grantee Pamela Ronald, Ph.D., of the University of California, Davis. To the estimated half of the world's population dependent on rice for food, this is potentially very good news. The work that may raise rice yields involves the discovery and cloning of a gene, called Xa21, that confers resistance to leaf blight, a disease that is responsible for major rice crop losses in Asia and Africa--possibly as much as half the crop in a bad year.

Dr. Ronald was studying the fundamental process of chemical signaling between organisms, specifically, how some plant genes evolve to encode proteins that sense the presence of certain other proteins in organisms that cause diseases. Plants in which these genes have evolved become resistant to diseases caused by a variety of viral, bacterial, and fungal pathogens. If the host plant's cells sense a pathogen, a number of genes are then activated that cause those plant cells that are in the vicinity of the invasion to die. This, in turn, limits the growth of the disease-causing organism. Rice proved to be an ideal plant in which to search for the genes responsible for the plant's defense because the genetics of rice is better understood than that of other grains like wheat and corn. However, the researchers predict that the techniques should eventually be applicable to these crops, as well.

In addition to isolating the gene for resistance from a wild type of rice and cloning it, Dr. Ronald and her colleagues successfully transferred the resistance gene to commercially important, but non-blight-resistant, rice plants. When the cloned gene was transferred to non-resistant plants, they became resistant. Thus, work originally initiated to explore an interesting biological problem now promises to have an important impact on world agriculture.


Song WY, Wang GL, Chen LL, Kim HS, Pi LY, Holsten T, Wang B, Zhai WX, Zhu H, Fauquet C, Ronald PC. A Receptor Kinase-Like Protein Encoded by the Rice Disease Resistance Gene, Xa21. Science 1995;270:1804-6.

Wang GL, Song WY, Ruan DL, Sideris S, Ronald PC. The Cloned Gene, Xa21 Confers Resistance to Multiple Xanthomonas oryzae pv. oryzae Isolates in Transgenic Plants. Molecular Plant-Microbe Interactions 1996;9:850-5.

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