Current phase-out schedules of the production and emission of CFC's indicate that chlorine loading in the stratosphere is not yet at its maximum. The recovery of stratospheric ozone is estimated to take time and ele vated levels of UV-B radiation are expected to occur throughout most of the next century. Despite numerous physiological studies of UV-B effects on plants, often grown in climate chambers, knowledge of UV-B effects on organisms and processes in natural aquatic or terrestrial ecosystems is poor. Currently it appears that UV-B radiation is not just an environmental stress' factor to plants. In various ways, which are incompletely understood, UV-B affects a wide range of physiological and ecological processes. Remarkably, recent field studies indicate that enhanced UV-B does not markedly affect photosynthesis, growth and primary production, but rather interferes with plant morphogenesis and plant and ecosystem functions relating to the secondary metabolism. This special issue and book UV-B and Biosphere is an attempt to cover this range and to report the progress made in the research of ecological effects of enhanced solar UV-B radiation. The papers in this book formed the basis of an international workshop entitled' UV-B and Biosphere' , December 15-18, 1995, in Wageningen, The Netherlands. A first reaction of Hans de Boois on the number of papers and sessions scheduled from Friday to Sunday morning was: far too many.

Human population is escalating at an enormous pace and is estimated to reach 9.7 billion by 2050. As a result, there will be an increase in demand for agricultural production by 60-110% between the years 2005 and 2050 at the global level; the number will be even more drastic in the developing world. Pathogens, animals, and weeds are altogether responsible for between 20 to 40 % of global agricultural productivity decrease. As such, managing disease development in plants continues to be a major strategy to ensure adequate food supply for the world. Accordingly, both the public and private sectors are moving to harness the tools and paradigms that promise resistance against pests and diseases. While the next generation of disease resistance research is progressing, maximum disease resistance traits are expected to be polygenic in nature and controlled by selective genes positioned at putative quantitative trait loci (QTLs). It has also been realized that sources of resistance are generally found in wild relatives or cultivars of lesser agronomic significance. However, introgression of disease resistance traits into commercial crop varieties typically involves many generations of backcrossing to transmit a promising genotype. Molecular marker-assisted breeding (MAB) has been found to facilitate the pre-selection of traits even prior to their expression. To date, researchers have utilized disease resistance genes (R-genes) in different crops including cereals, pulses, and oilseeds and other economically important plants, to improve productivity. Interestingly, comparison of different R genes that empower plants to resist an array of pathogens has led to the realization that the proteins encoded by these genes have numerous features in common. The above observation therefore suggests that plants may have co-evolved signal transduction pathways to adopt resistance against a wide range of divergent pathogens. A better understanding of the molecular mechanisms necessary for pathogen identification and a thorough dissection of the cellular responses to biotic stresses will certainly open new vistas for sustainable crop disease management. This book summarizes the recent advances in molecular and genetic techniques that have been successfully applied to impart disease resistance for plants and crops. It integrates the contributions from plant scientists targeting disease resistance mechanisms using molecular, genetic, and genomic approaches. This collection therefore serves as a reference source for scientists, academicians and post graduate students interested in or are actively engaged in dissecting disease resistance in plants using advanced genetic tools.

The adv antages of those systems are counterbalanced by some important dis- vantages. For one, in heterotrophic and mixotrophic systems high concentrations of organic ingredients are required in the nutrient medium (particularly sugar at 2% or more), associated with a high risk of microbial contamination. How, and to which extent this can be avoided will be dealt with in Chapter 3. Other disadvantages are the difficulties and limitations of extrapolating results based on tissue or cell c- tures, to interpreting phenomena occurring in an intact plant during its development. It has always to be kept in mind that tissue cultures are only model systems, with all positive and negative characteristics inherent of such experimental setups. To be realistic, a direct duplication of in situ conditions in tissue culture systems is still not possible even today in the 21st century, and probably never will be. The organization of the genetic system and of basic cell structures is, however, essentially the same, and therefore tissue cultures of higher plants should be better suited as model s- tems than, e.g., cultures of algae, often employed as model systems in physiological or biochemical investigations. The domain cell and tissue culture is rather broad, and necessarily unspecif ic. In terms of practical aspects, basically five areas can be distinguished (see Figs. 1.1, 1.2 ), which here shall be briefly surveyed before being discussed later at length.

This volume is the most comprehensive and detailed account of seed proteins so far published and the first dedicated volume for a number of years. It covers the major storage protein groups (prolamins, 2S albumins, 7Sglobulins, and 11S globulins), focusing on those present in crops. It also covers other widely distributed groups of proteins including lectins, inhibitors, antifungal proteins, thionins and oil body protein (oleosins). The breadth of coverage of the proteins is wide, including their structures and properties, evolutionary relationships, classical and molecular genetics and mechanisms of synthesis, trafficking and deposition within the cells. It should therefore become a standard source book for active research scientists as well as for higher level teaching.

The aim of this project is to produce a the world's most comprehensive reference in plant sciences. The Plant Sciences will be published both in print and online; the online text will be regularly updated to enable the reference to remain a useful authoritative resource for decades to come. The aim is to provide a sustainable superstructure on which can be built further volumes as plant science evolves. The first edition will contain ten volumes, with approximately 20-30 chapters per volume. The target audience for the initial ten volumes will be upper-division undergraduates, as well as graduate students and practitioners looking for an entry into a particular topic. The Encyclopedia will provide both background and essential information in plant biology. Topics will include plant genetics, genomics, biochemistry, natural products, proteins, cell biology, development, reproduction, physiology, ecology, evolution, systematics, biodiversity, and applications, including crop improvement and non-food applications.

This work is a comprehensive collection of articles that cover aspects of cell wall research in the genomic era. Some 2500 genes are involved in some way in wall biogenesis and turnover, from generation of substrates, to polysaccharide and lignin synthesis, assembly, and rearrangement in the wall. Although a great number of genes and gene families remain to be characterized, this issue provides a census of the genes that have been discovered so far. The articles comprising this issue not only illustrate the enormous progress made in identifying the wealth of wall-related genes but they also show the future directions and how far we have to go. As cell walls are an enormously important source of raw material, we anticipate that cell-wall-related genes are of significant economic importance. Examples include the modification of pectin-cross-linking or cell-cell adhesion to increase shelf life of fruits and vegetables, the enhancement of dietary fiber contents of cereals, the improvement of yield and quality of fibers, and the relative allocation of carbon to wall biomass for use as biofuels. The book is intended for academic and professional scientists working in the area of plant biology as well as material chemists and engineers, and food scientists who define new ways to use cell walls.

This Fourth Edition of Principles of Seed Science and Technology, like the fIrst three editions, is written for the advanced undergraduate student or lay person who desires an introduction to the science and technology of seeds. The fIrst nine chapters present the seed as a biological system and cover its origin, development, composition, function (and sometimes nonfunction), performance and ultimate deterioration. The last nine chapters present the fundamentals of how seeds are produced, conditioned, evaluated and distributed in our modern agricultural society. Two new chapters have been added in this fourth edition, one on seed ecology and the second on seed drying. Finally, revisions have been made throughout to reflect changes that have occurred in the seed industry since publication of the Third Edition. Because of the fundamental importance of seeds to both agriculture and to all of society, we have taken great care to present the science and technology of seeds with the respect and feeling this study deserves. We hope that this feeling will be communicated to our readers. Furthermore, we have attempted to present information in a straight-forward, easy-ta-read manner that will be easily understood by students and lay persons alike. Special care has been taken to address both current state-of-the-art as well as future trends in seed technology.