Production of novel polymers in transgenic plants

The production of novel or modified polymers in transgenic plants can be divided into the manipulation of plant metabolism to modify in planta endogenous polymers and the introduction of metabolic pathways from other plant species or even bacteria into crop species to produce novel polymers. Polymers of interest are starch, fructans and polyhydroxyalkanoates (PHA). During the last few years several genes involved in starch biosynthesis have been isolated. Following the antisense or the overexpression approach transgenic plants were created which produced starches displaying altered physical and chemical properties. The isolation of genes necessary for the synthesis of fructans from agronomically unfavourable plant species will allow the production of this polymer in a set of transgenic crops on a reduced cost level. The production of small amounts of PHB in transgenic plants was demonstrated some years ago. For commercial production of PHB it is necessary to further increase the capacity of transgenic plants to synthesise and store PHB and study the possibilities to manipulate metabolic pathways of the plant for the production of other PHA precursors. (C) 1998 Elsevier Science Limited. All rights reserved