Killer gene

Biologists in Australia and Japanhave genetically engineered tobaccoplants so that they destroy their ownseeds. They say the same techniqueshould work in citrus crops. AnnaKoltunow of the division of horticulture of the CSIRO, Australia'snational research agency inAdelaide, and Fumio Takaiwa ofJapan's National Institute of Agrobiological Resources in Tsukuba,linked a gene that kills cells with a'promoter' DNA sequence thatswitches on a gene active duringseed formation. The researchers calltheir gene SDLS-2. The cell-killingcomponent is found in a wide rangeof plants, and kills unwanted cellsduring plant development. Theresearchers are now inserting SDLS-2 into citrus plants, and are positiveabout the chances of success.