First attempts to isolate plant genes were for those genes that are abun- dantly expressed in a particular plant organ at a specific stage of devel- opment. However, many important gene products are produced in a very minute quantity and in specialized cell types. Such genes can now be isolated using a variety of approaches, some of which are described in this volume. The rapid progress during the last decade in regeneration of a number of crop plants and the availability of molecular tools to introduce foreign genes in plants is allowing the engineering of specific traits of agri- cultural...