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.

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.

Authored by an integrated committee of plant and animal scientists, this review of newer molecular genetic techniques and traditional research methods is presented as a compilation of high-reward opportunities for agricultural research. Directed to the Agricultural Research Service and the agricultural research community at large, the volume discusses biosciences research in genetic engineering, animal science, plant science, and plant diseases and insect pests. An optimal climate for productive research is discussed.

This book is a reference book based on the contribution made by eminent scientists (toxicologists) from the leading laboratories of the world. This book includes discussions of toxins produced by microbes, particularly fungi and bacteria, their chemical characterization, mechanism of action at the cellular and molecular level and also exploitation of TOX genes for the management of insect pests, weeds and plant pathogens.

William C. Taylor Department of Genetics University of California Berkeley, California 94720 It is evident by now that there is a great deal of interest in exploiting the new technologies to genetically engineer new forms of plants. A purpose of this meeting is to assess the possibilities. The papers that follow are concerned with the analysis of single genes or small gene families. We will read about genes found within the nucleus, plastids, and bacteria which are responsible for agri culturally important traits. Given that these genes can be isolated by recombinant DNA techniques, there are two possible strategies for plant engineering. One involves isolating a gene from a cultivated plant, changing it in a specific way and then inserting it back into the same plant where it produces an altered gene product. An example might be changing the amino acid composition of a seed pro tein so as to make the seed a more efficient food source. A second strategy is to isolate a gene from one species and transfer it to another species where it produces a desirable feature. An example might be the transfer of a gene which encodes a more efficient pho tosynthetic enzyme from a wild relative into a cultivated species. There are three technical hurdles which must be overcome for either strategy to work. The gene of interest must be physically isolated.

The Indian Society of Mycology and Plant Pathology, which is consistently striving to serve the fraternity of plant pathology with its all round efforts, has recently undertaken an arduous but zealous project to start the publication of series of Annual Reviews in the discipline. The basic philosophy to start the publication of annual reviews has been to make available the latest developments in the different areas of the discipline to the students, scientists and libraries.