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 offer the unique challenge of studying
the interaction of three separate genetic systems in a single organism.
The molecular approach has provided, in recent years, a wealth of
important information about how plants function, and how they interact
with bacteria, fungi and viruses. Furthermore, plant development
involves the regulation of gene expression in response to intern al and
external signals, and plant molecular biology has provided a fundamental
insight into how this development is regulated. This is not only of
considerable scientific interest, but also has important implications
for the production of plants and plant products in agriculture,
horticulture and the food industries.