Summarizing research progress achieved in 32 areas of cell biology covered in this series, this volume places special emphasis on the following topics: recognition in parasitic and symbiotic systems - the molecular biology and genetics of susceptibility and resistance of plants and animals to pathogens, parasites and symbionts - the cell to cell recognition and differentiation - the most challenging problems in developmental biology of plants and animals - the plasticity in cell to cell communication which plays a major role in cell differentiation and function.The final report of the NATO Special Programme on Cell in Cell Signals in Plants and Animals, running from 1984 to 1990 unter the auspices of the NATO Science Committee.Summarizing research progress achieved in 32 areas of cell biology covered in this series, this volume places special emphasis on the following topics: recognition in parasitic and symbiotic systems - the molecular biology and genetics of susceptibility and resistance of plants and animals to pathogens, parasites and symbionts - the cell to cell recognition and differentiation - the most challenging problems in developmental biology of plants and animals - the plasticity in cell to cell communication which plays a major role in cell differentiation and function.Recognition in Parasitic and Symbiontic Systems.- Phytotoxins and Plant Pathogenesis.- Genetics.- Toxins in relation to plant resistance; evolution of pathogens.- Structure and mode of action.- Applications.- Conclusions.- Recent Advances in Plant-Microbe Interactions.- Interactions between plants and microbes: Background information.- Signals in the interaction of Rhizobium and leguminous plants.- Chemotaxis.- Attachment.- Activation of nodulation genes.- Inhibition of nod gene activation.- nod gene products.- Infection thread formation.- Release of bacteria from the infection thread.- Bacteroid development.- Effective nitrogen fixation.- Induction of nodulinslcn