In the preface to the first edition ofthis book, we expressed a conviction that there was a need for a short book that highlighted important advances in the new discipline of plant molecular biology. The rapid development of this topic has been brought about by the recognition of the unique properties of plants in the study of growth and development together with the application of recombinant DNA techniques to tackle these problems. Plant cells contain DNA in nuclei, plastids and mitochondria, and so ofTer the unique challenge of studying the interaction of three separate genetic systems in...