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.

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.

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

Microbial toxins are secondary metabolites that accumulate in the organism and, to a large extent, are metabolically inactive towards the organism that produces them. The discovery of penicillin, a secondary metabolite of Penicillium notatum West (= P. chrysogenum Thom), in 1929 marked a milestone in the development of antibiotics (microbial toxins). In the intensive studies that followed this discovery, scientists chemically characterized several new molecules (toxins) from secondary metabolites of microbes, some having a definite function in causing pathogenesis in plants. Toxins are also known to playa significant role in inciting animal (human) and insect diseases and as plant growth regulators. Many common toxins have also been isolated from different microbes exhibiting a wide spectrum of biological activity. Toxins are broadly divisible into several characteristic groupings - polyketides, oxygen heterocyclic compounds, pyrons, terpenoidS, amino acids - diketopiperazines, polypeptides etc. Recent research has indicated that these toxins play an important role in plant pathogenesis, disease epidemics, plant breeding, biological control of plant pathogens and insect pests, induced resistance, plant-pathogen interactions etc. Toxins produced by weed pathogens are exploited as lead molecules in developing environmentally friendly herbicides.

Established almost 30 years ago, Methods in Microbiology is the most prestigious series devoted to techniques and methodology in the field. Now totally revamped, revitalized, with a new format and expanded scope, Methods in Microbiology will continue to provide you with tried and tested, cutting-edge protocols to directly benefit your research. - Focuses on the methods most useful for the microbiologist interested in the way in which bacteria cause disease - Includes section devoted to 'Approaches to characterising pathogenic mechanisms' by Stanley Falkow - Covers safety aspects, detection, identification and speciation - Includes techniques for the study of host interactions and reactions in animals and plants - Describes biochemical and molecular genetic approaches - Essential methods for gene expression and analysis - Covers strategies and problems for disease control