Recent advances in gene technology, plant transformation, and the growing knowledge of DNA sequences of plants as well as of their most important parasites and symbionts offer many interesting prospects for the breeding of new crop varieties. This was not only recognized by the major seed companies, but also by the governments of developing countries and by worldwide foundations supporting their agriculture. The know-how gained by the seed companies on crops important for the agricultural industry in developed countries could easily be provided for free to the international and national organizations dedicated to development of crops important in the third world. Results obtained worldwide become easily available to everybody through the scientific literature. Likewise, agricultural research in, e.g., the USA or Europe profits from the natural plant gene pool available in the third world. All this definitely provides for the possibility of fast change, new prosperity and security of food supply in the whole world, if properly applied. The fast development also asks for ethical and sociopolitical considerations, whereby not doing the right can be as much a mistake as doing the wrong.

Recent advances in gene technology, plant transformation, and the growing knowledge of DNA sequences of plants as well as of their most important parasites and symbionts offer many interesting prospects for the breeding of new crop varieties. This was not only recognized by the major seed companies, but also by the governments of developing countries and by worldwide foundations supporting their agriculture. The know-how gained by the seed companies on crops important for the agricultural industry in developed countries could easily be provided for free to the international and national organizations dedicated to development of crops important in the third world. Results obtained worldwide become easily available to everybody through the scientific literature. Likewise, agricultural research in, e.g., the USA or Europe profits from the natural plant gene pool available in the third world. All this definitely provides for the possibility of fast change, new prosperity and security of food supply in the whole world, if properly applied. The fast development also asks for ethical and sociopolitical considerations, whereby not doing the right can be as much a mistake as doing the wrong.

Interdependence between species is a law of nature. The degree of this interdependence is vividly evident in the plant-microbial world. Indeed, there is no axenic plant in nature and one finds various forms of interac tions between these two kingdoms ranging from completely innocuous to obligate parasitic. Most of these interactions are poorly understood at the molecular and physiological levels. Only those few cases for which a molecular picture is emerging are discussed in this volume. With the advent of recombinant DNA technology and the realization that some of these interactions are very beneficial to the host plant, a spate of activity to understand and manipulate these processes is occurring. Microbes interact with plants for nutrition. In spite of the large number of plant-microbe interactions, those microbes that cause harm to the plants (i. e., cause disease) are very few. It is thus obvious that plants have evolved various defense mechanisms to deal with the microbial world. The mecha nisms for protection are highly diverse and poorly understood. Some pathogens have developed very sophisticated mechanisms to parasitize plants, an excellent example for this being crown gall caused by a soil bac terium, Agrobacterium tumefaciens. A remarkable ingenuity is exhibited by this bacterium to manipulate its host to provide nitrogenous compounds which only this bacterium can catabolize. This is carried out by a direct gene transfer mechanism from bacteria to plants."