Photosynthesis occurs in chloroplasts which are complex structures in the green parts of plants. The action of sunlight upon chlorophyll, the primary component of choroplasts, is vital to life since it gives rise to the production of organic compounds and oxygen - so life is ultimately dependent on the properties of chloroplasts. In this book an international group of research workers review the recent findings about the development of chloroplasts: in turn the chapters lucidly examine their structure, composition, genetics and biochemistry.

This book collects the Proceedings of a workshop sponsored by the European Molecular Biology Organization (EMBO) entitled "Pro teins Involved in DNA Replication" which was held September 19 to 23,1983 at Vitznau, near Lucerne, in Switzerland. The aim of this workshop was to review and discuss the status of our knowledge on the intricate array of enzymes and proteins that allow the replication of the DNA. Since the first discovery of a DNA polymerase in Escherichia coli by Arthur Kornberg twenty eight years ago, a great number of enzymes and other proteins were des cribed that are essential for this process: different DNA poly merases, DNA primases, DNA dependent ATPases, helicases, DNA liga ses, DNA topoisomerases, exo- and endonucleases, DNA binding pro teins and others. They are required for the initiation of a round of synthesis at each replication origin, for the progress of the growing fork, for the disentanglement of the replication product, or for assuring the fidelity of the replication process. The number, variety and ways in which these proteins inter act with DNA and with each other to the achievement of replication and to the maintenance of the physiological structure of the chromo somes is the subject of the contributions collected in this volume. The presentations and discussions during this workshop reinforced the view that DNA replication in vivo can only be achieved through the cooperation of a high number of enzymes, proteins and other cofactors.

The solanaceous family is one of the most interesting and diverse plant groups among the dicotyledons. Plants of various genera are grown for their edible parts, for drugs, or for ornamental purposes. The six genera grown primarily as ornamental plants are: Browallia, Brunsfelsia, Datura, Nicotiana, Petunia, and Salpiglossis. Of these, Petunia is the most economically important in terms of worldwide use as an ornamental plant. In addition to its horticultural value and prominence, the genus Petunia plays a key role as experimental plant material in a broad range of horticultural and biological research endeavors. Because of the broad range of commercial and research interest in Petunia, the collaborating authors believed it was appropiate to prepare a monograph dealing in a comprehensive manner with all economic and biological facets of the genus Petunia. The authors sincerely hope that this monograph will be of resource value and stimulating to students, researchers, and workers in industry interested in having a compendium of the knowledge available on the genus Petunia. KENNETH C. SINK Contents Introduction. By K. C. Sink 1 1.1 Survey of Petunia as a Research Species 1 2 1.2 Survey of Petunia as an Economic Plant Species 2 Taxonomy. By K. C. Sink ....... 3 2.1 Geographical Distribution ...... 3 2.2 Status of Petunia Within the Solanaceae 3 2.3 Early Taxonomie Studies . . . . . . . 4 2.4 Species Described by Fries, Steere, Smith, and Downes 5 ...... 7 2.5 Origin of the Cultivated P. hybrida Vilm.

With contributions by numerous experts