Rice knockouts

There is a pressing need for selective gene targeting techniques that can manipulate the rice genome. In an Advanced Online Publication in Nature Biotechnology, Terada et al. describe an efficient procedure for targeted gene disruption by homologous recombination in rice (Nature Biotechnology 9 September 2002, DOI:10.1038/nbt737). They decided to target the Waxy gene, which encodes an amylose synthesis enzyme, because it affects rice grain quality and quantity, and because associated phenotypes can be easily measured. They inactivated the Waxy gene by insertion of a hygromycin-resistance cassette into intron 1 and used strong positive/negative selection to determine that around 1% of transformants contained a disrupted Waxyallele resulting from homologous recombination.