Research on the interaction between plants and microbes has attracted considerable attention in recent years. The use of modem genetic techniques has now made possible a detailed analysis both of plant and of microbial genes involved in phytopathogenic and beneficial interactions. At the biochemical level, signal molecules and their receptors, either of plant or of microbial origins, have been detected which act in signal transduction pathways or as co-regulators of gene expression. We begin to understand the molecular basis of classical concepts such as gene-for-gene relationships, hypersensitive response, induced resistance, to name just a few. We realize, and will soon exploit, the tremendous potential of the results of this research for practical application, in particular to protect crop plants against diseases and to increase crop yield and quality. This exclung field of research, which is also of truly interdisciplinary nature, is expanding rapidly. A Symposium series has been devoted to it which began in 1982. Recently, the 5th International Symposium on the Molecular Genetics of Plant-Microbe Interactions was held in Interlaken, Switzerland. It brought together 640 scientists from almost 30 different countries who reported their latest research progress in 47 lectures, 10 short oral presentations, and on over 400 high-quality posters. This book presents a collection of papers that comprehensively reflect the major areas under study, explain novel experimental approaches currently in use, highlight significant advances made over the last one or two years but also emphasize the obstacles still ahead of us.

Table of Contents:
Molecular strategies in the interaction between Agrobacterium and its hosts.- Signal transduction via VirA and VirG in Agrobacterium.- The T-DNA on its way from Agrobacterium tumefaciens to the plant.- Functional organization of the regions responsible for nopaline and octopine catabolism in Ti plasmids of Agrobacterium tumefaciens.- Gene-for-gene relationships specifying disease resistance in plant-bacterial interactions.- Avirulence gene D from Pseudomonas syringae pv. tomato and its interaction with resistance gene Rpg4 in soybean.- Genes and signals controlling the Pseudomonas syringae pv. phaseolicola-plant interaction.- The hrp gene cluster of Erwinia amylovora.- Characterization of genes from Xanthomas campestris pv. vesicatoria that determine avirulence and pathogenicity on pepper and tomato.- Pectic enzyme production and bacterial plant pathogenicity.- Molecular analysis of a gene that affects extracellular polysaccharide production and virulence in Pseudomonas solanacearum.- Interactions between Arabidopsis thaliana and phytopathogenic Pseudomonas pathovars: A model for the genetics of disease resistance.- Interaction between Arabidopsis thaliana and Xanthomonas campestris.- Exopolysaccharides in the interaction of the fire-blight pathogen Erwinia amylovora with its host cells.- Iron as a modulator of pathogenicity of Erwinia chrysanthemi 3937 on Saintpaulia ionantha.- Genetic and physiological aspects of the pathogenic interaction of Clavibacter michiganense subsp. michiganense with the host plant.- DNA probes as tools for the study of host-pathogen evolution: The example of Pseudomonas solanacearum.- Overview on genetics of nodule induction: Factors controlling nodule induction by Rhizobium meliloti.- NodRm-1, a sulphated lipo-oligosaccharide signal of Rhizobium meliloti elicits hair deformation, cortical cell division and nodule organogenesis on alfalfa roots.- Rhizobium meliloti nodulation gene regulation and molecular signals.- Genetic and biochemical studies on the nodulation genes of Rhizobiumleguminosarum bv. viciae.- The biochemical function of the Rhizobium leguminosarum proteins involved in the production of host specific signal molecules.- Studies on the function of Rhizobium meliloti nodulation genes.- Genetics of host specific nodulation by Bradyrhizobium japonicum.- Signal exchange mediates host-specific nodulation of tropical legumes by the broad host-range Rhizobium species NGR234.- The use of the genus Trifolium for the study of plant-microbe interactions.- Roles of lectin in the Rhizobium-legume symbiosis.- Analyses of the roles of R.meliloti exopolysaccharides in nodulation.- The role of the Rhizobium meliloti exopolysaccharides EPS I and EPS II in the infection process of alfalfa nodules.- Regulation of nitrogen fixation genes in Rhizobium meliloti.- Complex regulatory network for nif and fix gene expression in Bradyrhizobium japonicum.- Genomic instability in Rhizobium: Friend or foe?.- Cytokinin production by rhizobia.- Molecular genetics of the hydrogen uptake system of Rhizobium leguminosarum.- ?-Glucuronidase (GUS) operon fusions as a tool for studying plant-microbe interactions.- Specificity of plant-fungus interactions: Molecular aspects of avirulence genes.- Mutual triggering of gene expression in plant-fungus interactions.- Fungal signals involved in the specificity of the interaction between barley and Rhynchosporium secalis.- Molecular determinants of pathogenesis in Ustilago maydis.- The b locus of Ustilago maydis: Molecular analysis of allele specificity.- An in planta induced gene ofPhytophthora infestans codes for ubiquitin.- Strategies for the cloning of genes in tomato for resistance to Fulvia fulva.- Downy mildew of Arabidopsis thaliana caused by Peronospora parasitica:A model system for the investigation of the molecular biology of host-pathogen interactions.- Host-pathogen interactions in the system Arachis hypogaea-Cercospora arachidicola.- Genesis of root nodules and function of nodulins.- Early nodulins in pea and soybean nodule development.- Different modes of regulation involved in nodulin gene expression in soybean.- Regulation of nodule-expressed soybean genes.- Patterns of nodule development and nodulin gene expression in alfalfa and Afghanistan pea.- Endocytosis and the development of symbiosomes in the pea-Rhizobium symbiosis.- Plant genetic control of nodulation in legumes.- Genetic and cellular analysis of resistance to vesicular arbuscular (VA) mycorrhizal fungi in pea mutants.- Agrobacterium rhizogenes T-DNA genes and sensitivity of plant protoplasts to auxins.- Chimaeras and transgenic plant mosaics: A new tool in plant biology.- Identification of signal transduction pathways leading to the expression of Arabidopsis thaliana defense genes.- Local and systemic gene activation following the hypersensitive response of plants to pathogens.- Properties of plant defense gene promoters.- Signals in plant defense gene activation.- A search for resistance gene-specific receptor proteins in lettuce plasma membrane.- Pathogenesis-related proteins exhibit both pathogen-induced and developmental regulation.- Pathogen-induced genes in wheat.- Biological activity of PR-proteins from tobacco; characterization of a proteinase inhibitor.- Molecular recognition in plants: Identification of a specific binding site for oligoglucoside elicitors ofphytoalexin accumulation.- Perception of pathogen-derived elicitor and signal transduction in host defenses.- Phosphoprotein-controlled changes in ion transport are common events in signal transduction for callose and phytoalexin induction.- Induced systemic resistance in cucumber in response to 2,6-dichloro-isonicotinic acid and pathogens.- Genetic aspects of phenazine antibiotic production by fluorescent pseudomonads that suppress take-all disease of wheat.- Secondary metabolites of Pseudomonas fluorescens strain CHA0 involved in the suppression of root diseases.- Tests of specificity of competition among Pseudomonas syringae strains on plants using recombinant ice- strains and use of ice nucleation genes as probes of in situ transcriptional activity.- Regulation of the synthesis of indole-3-acetic acid in Azospirillum.- Author Index.