SCIENTISTS are making headway in using genetic engineering techniques to develop commercial varieties of rice strains that are resistant to diseases. Initial trials by researchers in China and Japan of rice strains modified to fight the red stripe virus, which in southeast Asia has been known to destroy entire harvests, have proved promising.

Tests are also due shortly in Texas of strains designed to combat the destructive rice water weevil, and British scientists are ready to test strains resistant to the rice tungro virus.

Yan Yitang and his colleagues from the Institute of Microbiology of the Chinese Academy of Sciences, implanted rice-plant cells with a gene that manufactures the protein coat of the red stripe virus. Tests show that protein coats taken from viruses appear to offer protection against them, for reasons not yet known.

The Chinese researchers report 10 of 16 transgenic varieties remained healthy when exposed to the red stripe virus and the remaining six showed only mild symptoms of the infection.

"We are very pleased with the results, but need to take it further," says Yan. "These genetically engineered plants will open up a new way." Yan's team is the only one to have transformed the Indica variety of rice. All other trials have been on the Japonica variety, which is found widely in Latin America and the West.