Toxins in Plant Disease presents a comprehensive coverage of plant disease toxins, both those for which there are reasonable evidence and those with fewer credentials. This book is primarily concerned with the mechanism wherein substances that interfere with metabolism or that alter the normal structure of protoplasm are produced and released (category 1); this includes the traditional toxins, which are usually of low molecular weight. It also describes category 2 mechanism, wherein substances that interfere with normal control of growth and development are produced and released; these microorganisms are classified as growth-affecting compounds. Moreover, this text addresses some high-molecular-weight compounds that contribute to vascular dysfunction. It further talks about the production, isolation, assay, genetics of production, mechanism of action, structure-activity relationship, metabolism, and applications of these toxins. This publication will provide a rational basis for future investigations and contribute to the eventual understanding of the role that toxins play in disease causation.

Toxins as chemical determinants of plant disease. Structural aspects of toxins. Molecular modes of action. Role of toxins in pathogenesis. Future prospects in toxin research.

Toxins produced by plant pathogens are known to play an important role in plant pathogenesis and are actively involved in part of the disease expression. This text deals with both host-specific and non-host specific toxins in order to describe host-pathogen interactions leading to disease development and their biotechnological exploitation using genetic engineering tools for disease and weed management.

Proceedings of the NATO Advanced Research Workshop on Phytotoxins and Plant Pathogenesis held at Capri, Italy, May 30 - June 3, 1988

There has been a significant surge of interest in the study of the physiology and biochemistry of plant host-parasite interactions in recent years, as evidenced by the number of research papers currently being published on the subject. The in creased interest is probably based on the evidence that effective management of many plant diseases is, for the most part, contingent upon a clear understanding of the nature of host-parasite interactions. This intensified research effort calls for a greater number of books, such as this one, designed to compile, synthesize, and evaluate widely scattered pieces of information on this subject. The study of host-parasite interactions concerns the struggle between plants and pathogens, which has been incessant throughout their coevolution. Such in teractions are often highly complex. Pathogens have developed sophisticated of fensive systems to parasitize plants, while plants have evolved diversified defen sive strategies to ward off potential pathogens. In certain cases, the outcome of a specific host-parasite interaction seems to depend upon the presence or efficacy of the plant's defense system. A plant may become diseased when a parasite manages to invade it, unhindered by preexisting defense systems and/or without eliciting the plant's induced resistance response(s). Absence of disease may re flect the inability of the invading pathogen to overcome the plant's defense sys tem(s).

For investigators engaged in the study of toxins generally, and host-specific toxins in particular, it is a rare treat to attend a meeting in which toxins involved in plant pathogenesis are emphasized. A gathering of this type provides opportunity to consider the discovery of new toxins, their chemical structures, genes encoding enzymes that control their biosyntheses, their sites of action and physiological effects on plants, and their roles (if any) in pathological processes. Having acknowledged the inspiration fostered by a 'toxin meeting', however, it is important to point out that the program of this symposium was generously sprinkled with 'nontoxin' talks. These contributions generated cross-disciplinary discussion and promoted new ways of thinking about relationships among factors required for plant disease development. The point can be illustrated by considering just one example. We have in the past often regarded diseases mediated by host-specific toxins and diseases involving 'gene-for-gene' relationships as representing two different classes of fungal/plant interaction. This is largely because the key molecular recognition event in so-called 'toxin' diseases leads to compatibility, whereas the corresponding event in 'gene-for-gene' diseases leads to incompatibility. Yet the race specific elicitors produced by the 'gene-for-gene' fungi Cladosporium fulvum (De Wit, Adv. Bot. Res. 21:147- 185, 1995) and Rhynchosporium secalis (Rohe et a1. , EMBO J.

Environmental pollution resulting from widespread pesticide application has become a serious worldwide problem. Plant Pathogenesis and Disease Control is an important new reference that addresses this problem by exploring the biochemical and molecular mechanisms of plant pathogenesis and emphasizing the use of "pest control agents" rather than "pesticides" for plant disease control. Topics examined include pathogenicity, the resistance of plants against pathogens, the offensive and defensive struggle between hosts and parasites, methods for using natural defense mechanisms to develop environmentally sound disease control agents, and the use of modern biotechnology for plant disease control. The book will be an essential reference for phytopathologists, plant biochemists, pesticide chemists, mycologists, plant cell technologists, and agricultural researchers.