Professor Ian Small has discovered a new mechanism that controls the production of proteins in plant organelles, the primary generators of energy used by all living organisms. He defined an abundant class of nuclear-encoded proteins that bind individual RNA sequences in chloroplasts and mitochondria, regulating whether or not that RNA is translated. This protein-RNA sequence recognition depends on a novel molecular code that Ian and his colleagues discovered. They showed that this code underlies male sterility and the restoration of fertility in plant breeding. The new code shows great practical promise in allowing us to modify specific RNA sequences, and hence specific gene products, in all living species.