During the last decade it has become clear that bacteria-plant interactions play an important role in agricultural science. In particular, symbiotic nitro gen fixation, plant tumorigenesis, and plant pathogenic bacteria have been extenSively investigated. Therefore, several of my colleagues suggested the importance of organizing a specialized symposium on the "Molecular genetics of the bacteria-plant interaction". This symposium was held in Germany, at the University of Bielefeld, in the autumn of 1982. The International Program Advisory Board, together with the National Organizing Committee, initially decided to concentrate on the following three topics: 1. Rhizobium-plant interaction 2. Agrobacterium-plant interaction 3. Plant pathogenic bacteria In retrospect, these topics proved to be most popular: Nearly all important groups working in this field contributed to the Bielefeld Symposium. The papers presented are now published as the Proceedings. It will be obvious that this book represents the most comprehensive collection of papers describing the molecular genetics of the bacteria-plant interaction. Scientists, as well as students, can use this book to learn about the basic principles and the current ideas that have recently been developed in this growing research area. The Symposium was financed by the Bundesministerium ftir Forschung und Technologie (Federal Ministry of Science and Technology). I express on behalf of the Organizing committee its sincere appreciation to this sponsor, without whom the Symposium would not have been possible. In addition, the help of several industrial companies is acknowledged.

Inhalt
A. General Introduction.- The Historical Background of the Bacteria-Plant Interaction.- The Rhizobium-Plant Interaction.- La Piste des Opines.- B. The Rhizobium-Plant Interaction.- I. The Rhizobium meliloti-Medicago sativa System.- Studies on Rhizobium meliloti Plasmids and on Their Role in the Control of Nodule Formation and Nitrogen Fixation: The pSym Megaplasmids and the Other Large Plasmids.- Studies on Rhizobium meliloti Plasmids and on Their Role in the Control of Nodule Formation and Nitrogen Fixation: A Strategy for Region-Specific Transposon Mutagenesis of pSym Megaplasmid.- Analysis of Symbiotic Nitrogen Fixation Genes Carried by the Rhizobium meliloti Mega-Plasmid.- Characterization of Rhizobium meliloti Genetic Loci Essential for Symbiotic Nitrogen Fixation.- Mapping and Regulation of the Structural Genes nifK, nifD, and nifH of Rhizobium meliloti.- Early Nodulation Genes of Rhizobium meliloti.- Symbiotic Nitrogen Fixation Genes of Rhizobium meliloti.- Vector Plasmids for in-Vivo and in-Vitro Manipulations of Gram-Negative Bacteria.- II. The Rhizobium leguminosarum-Pisum sativum System.- Genetic Analysis of pRL1 JI, a Symbiotic Plasmid of Rhizobium leguminosarum.- Natural Variation in Rhizobium Plasmids.- Analysis of Nodule-Specific Plant and Bacteroid Proteins in Pea Plants Inoculated by Transposon Mutagenized Rhizobium leguminosarum.- III. The Rhizobium japonicum-Glycine max System.- Rhizobia Use Free-Living N2 Fixation to Promote Growth by a Mechanism of Crossfeeding.- The Nitrogenase Genes of Rhizobium japonicum.- The Structure and Organization of the Soybean Leghemoglobin Genes.- The Role of Plant Genes in Soybean-Rhizobium Interactions.- IV. The Interaction of Different Rhizobium Species with Plants.- General Organization of Nitrogen Fixation Genes inRhizobium phaseoli.- Identification of Nitrogen Fixation and Nodulation Genes on a Large Plasmid from a Broad Host Range Rhizobium sp..- Identification, Broad Host Range Mobilization and Mutagenesis of a Rhizobium trifolii Sym::R68.45 Cointegrate Plasmid.- Genetic Analysis of the Symbiotic Regions in Rhizobium trifolii and Rhizobium parasponia.- Molecular Anatomy of the Symbiotic Region in Rhizobium trifolii and Rhizobium parasponia.- Stem Nodulation in Aeschynomene: A Model System for Bacterium-Plant Interactions.- C. The Agrobacterium-Plant Interaction.- I. The Tumor-Inducing Plasmids of Agrobacterium.- Onc- and vir-Genes Located on the Ti-Plasmid of Agrobacterium tumefaciens.- Plasmid Genes Essential for the Interactions of Agrobacteria and Rhizobia with Plant Cells.- Genetic Analysis of Host Range Expression by Agrobacterium.- The Biology of Genetic Transformation of Higher Plants by Agrobacterium rhizogenes.- Expression of the T-Region of Octopine Plasmid pTi Ach5 into Protein in Bacterial Systems.- II. The Role of T-DNA in Transformed Plant Cells.- Liposomes as a Carrier of Ti Plasmid into Protoplasts.- Plant Protoplast Transformation by Agrobacterium tumefaciens and its Ti Plasmid DNA.- The Study of Integration of Tumor-Inducing DNA from the Nopaline Ti Plasmid of Agrobacterium tumefaciens.- Transcription of the Ti-Plasmid in Crown Gall Tumors.- TR Genes Involved in Agropine Production.- Transcription of T-DNA in Octopine and Nopaline Crown Gall Tumours.- Genetic Analysis of T-DNA and Regeneration of Transformed Plants.- D. Plant Pathogenic Bacteria and Related Aspects.- The Genetics of the Cherry Pathogen, Pseudomonas syringae pathovar morsprunorum.- Towards the Genetical Analysis of Pathogenicity of Xanthomonas campestris.- Molecular Analysis of Virulence Genesin Pseudomonas solanacearum.- Cloning of Genes Involved in Bacterial Ice Nucleation and Fluorescent Pigment/Siderophore Production.- The Genetics of Indoleacetic Acid Production and Virulence in Pseudomonas savastanoi.- Azospirillum Genetics.- Genome Rearrangement of the Rhizobiaceae.