Marker-Assisted Rice
Breeding - 95



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Project Leader and Principal UC Investigators

Pamela C. Ronald, Assistant Professor, Department of Plant Pathology, UC Davis

David J. Mackill Research Geneticist, USDA-ARS, Department of Agronomy and Range Science, UC Davis

The overall objective of this project is to develop a method to rapidly screen California rice varieties for agronomically important genes. The tools of choice in these molecular investigations are DNA-based markers that tell researchers the precise location of sought-after genes.

Researchers successfully developed a DNA marker to identify the wide compatibility gene in japonica rice. The presence of this gene makes it possible to intercross rice varieties to transfer useful traits without the barriers commonly caused by sterility of first generation hybrids.

Using this technique the researchers were able to identify progeny of a javanica-japonica cross with the wide compatibility gene. Researchers are optimistic that DNA marker profiles will help track other important rice genes, such as stem rot resistance and submergence tolerance.

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Project scientists also cloned RAPD (random amplified polymorphic DNA) markers being used by USDA geneticists to 'fingerprint' California germplasm. Once these clones are characterized further, the germplasm screening method could be carried out at virtually any location with mini- mal equipment or molecular biology skills. Such techniques are already in use at the International Rice Research Institute in the Philippines and at other rice research facilities.

Perhaps one of the biggest developments coming out of this laboratory was the successful genetic engineering of disease resistance into rice. Professor Ronald's research was on bacterial blight, a pathogen that affects many crops throughout the world. Because of California's relatively dry climate, however, bacterial blight is not a problem for California rice growers.

This research was not funded by the Rice Research Board. Nonetheless, this work may yield important clues on the mechanisms of disease resistance in rice. The hope is that future engineering will lead to resistance of other intractable disease problems, such as stem rot and aggregate sheath spot.

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