Plants use resources, i.e. carbon, nutrients, water and energy, either for growth or to defend themselves from biotic and abiotic stresses. This volume provides a timely understanding of resource allocation and its regulation in plants, linking the molecular with biochemical and physiological-level processes. Ecological scenarios covered include competitors, pathogens, herbivores, mycorrhizae, soil microorganisms, carbon dioxide/ozone regimes, nitrogen and light availabilities. The validity of the "Growth-Differentiation Balance Hypothesis" is examined and novel theoretical concepts and approaches to modelling plant resource allocation are discussed. The results presented can be applied in plant breeding and engineering, as well as in resource-efficient stand management in agriculture and forestry.

Allelopathy is a fascinating and perplexing topic that concerns the chemical interactions of plants. It has profound implications in agriculture and forestry where species are grown artificially in mixture, with no evolutionary history of co-existence. The topic of allelopathy is widely credited as commencing in 1937, when the term 'allelopathy' was coined by Molisch. However, the concept of allelopathy has been recorded since Greek and Roman times, became extremely controversial in the first half of the 19th century, and remains so today. This book concerns a virtually unknown treatise by Justus Ludewig von Uslar, published in 1844, which emerges as the first book entirely devoted to the concept of allelopathy. The book provides the historical background to allelopathic knowledge, from antiquity to c. 1840. It also provides for the first time a biography of Justus Ludewig von Uslar, who is best known as the first Consul-General for Hannover in Mexico, and Director of the Mexican Company, a British venture mining company. In many ways von Uslar epitomises the tradition of the gentleman scientist of the 19th century. The book then offers a full translation into English of von Uslar's rare treatise, which foreshadows many ideas current in allelopathic research.

There is an urgent need to expand our knowledge of both the nature of the toxigenic fungi that are widespread on economically-important plants and the effect of their toxic secondary metabolites on human health. Informa tion about the production of mycotoxins by plant pathogens, particularly by species of Fusarium, Aspergillus and Penicillium, their occurrence in infected plants, as well as their role in the plant-pathogen interaction, for example as virulence/pathogenicity factors, is a pre-requisite for preventing plant disease and hence for reducing the Ievels of mycotoxin contamination. Fusarium infections in cereals and other crops are a particular problern world-wide and recent epidemics on wheat in Europe, the USA and Canada have again focused attention on this problem. Fur thermore, species ofAspergillus and Penicillium and their related mycotoxins, particularly Ochratoxin A, represent another consistent problern on cereals and grapes, especially in Europe where 40% of the global grape crop is grown. The aim of this publication is to gather together specialist updated reviews based on papers originally presented during a Workshop of EU Cost Action 835 entitled 'Agriculturally Important Taxigenie Fungi', held in Rome, 7-8 October 1999 at the Plant Pathology Research Institute. We hope the diversity of the contents will stimulate discussion, encourage the sharing of information and result in cross-fertilization of ideas needed for the solution of the present problems. This special issue will be of particular value to interdisciplinary scientists and especially mycologists, mycotoxicologists, plant pathologists and those concerned about the quality of food and food products.

Plant Pathogenic Bacteria includes symposia and research papers presented at the 10th International Conference on Plant Pathogenic Bacteria. The book provides the complete text of 22 symposia papers that summarize the state-of-the-art of the many facets of phytobacteriology including disease control, taxonomy, genetics of pathogenicity, virulence factors, as well as detection and diagnosis. These topics are also included among research papers, presented orally or as posters at the conference, and here presented in research paper format, conveniently separated in different sections by subject matter. This book will be an essential resource for scientists and students with an interest in plant pathogenic bacteria for it provides much new data and summarizes current thinking in almost all areas of the science. Nowhere else can one find so much information on plant pathogenic bacteria in a single resource.

This is a comprehensive up-to-date treatise including information on virus-, viroid-, and phytoplasma-induced potato diseases. The chapters of this book were written by internationally well-known experts and include novel techniques of detection, virus isolation, transmission, and epidemiology of the pathogens.

The explosive increase in the world's human population, with conse quent need to feed an ever-increasing number of hungry mouths, and the largely resultant disturbances and pollution of the environment in which man must live and produce the things he needs, are forcing him to search for means of solving the first problem without intensifying the latter. Food production requires adequate assurance against the ravages of insects. In the last three decades short-sighted, unilateral and almost exclusive employment of synthesized chemicals for insect pest control has posed an enormous and as yet unfathomed contribution to the degradation of our environment, while our insect pest problems seem greater than ever. Properly viewed, pest control is basically a question of applied ecology, yet its practice has long been conducted with little regard to real necessity for control, and in some cases, with little regard to various detrimental side-effects or long-term advantage with respect, even, to the specific crop itself. This book deals fundamentally with these questions. The development of pesticide resistance in many of the target species, against which the pesticides are directed, has occasioned an ever-increasing load of applications and complexes of different kinds of highly toxic materials. This has been made even more "necessary" as the destruction of natural enemies has resulted, as a side effect, in the rise to pest status of many species that were formerly innocuous. The application of broad-spec trum pesticides thus has many serious and self-defeating features."

G proteins are the key regulators for a wide range of cellular processes in animals and plants. In comparison to animals and yeast, plants have a single Rho-GTPase subfamily called Rho-like GTPases (ROPs). The ROP family of monomeric GTPases has emerged as a versatile and key regulator in plant signal transduction processes. During the past few years' studies on plant RHO-type (ROP) GTPase have generated new insights into their role in diverse processes ranging from cytoskeletal organization, polar growth, development to stress and hormonal responses. Studies have shown that plants have evolved specific regulators and effector molecules. ROP GTPases possess the ability to interact with these multiple regulator and effector molecules that ultimately determines their signaling specificity. Recently, genome wide studies in plants have shown that the Arabidopsis genome encodes 93, and rice has nearly 85 small GTPase homologs. And we have been able to identify four new homologs in the rice genome. Here, we focus on the complete phylogenetic, domain, structural and expression analysis during stress and various developmental processes of small GTPases in plants. The comparison of gene expression patterns of the individual members of the GTPase family may help to reveal potential plant specific signaling mechanisms and their relevance. Also, we are summarizing the role of currently known ROP GTPases and their interacting proteins with brief description, simultaneously, comparing their expression pattern based on microarray data. Overall, we will be discussing the functional genomic perspective of plant Rho like GTPases and their role in regulating several physiological processes such as stress, hormonal, pollen tube, root hair-growth and other developmental responses.

The seventeenth symposium of the British Mycological Society was held jointly with the British Society for Plant Pathology and the Society of Irish Plant Pathologists. The subject of the symposium was Phytophthora, the organism responsible for many plant diseases, most notably potato blight. This 1991 book presents the results of the meeting in a wide-ranging volume incorporating chapters discussing the history of potato blight, host-pathogen reactions, systematics and intraspecific variation, molecular and genetic studies and the development of effective control methods. Arguably the most studied of all plant pathogens, Phytophthora remains a problem in modern agriculture.

It appears that a comprehensive and up-to-date book on the impact of virus diseases on the major crops in developing countries is now much needed, especially as there have been rapid advances in the biological and molecular characterization and detection of the pathogens and possible approaches for their control. On the other hand, the economic losses caused by many of these diseases are tremendous and much of the accumulated knowledge to diminish the crop losses has not filtered through, or cannot be applied. This book is focused on the important crops. Each chapter on a specific crop will include inter alia, geographical distribution, the viruses - symptoms, damage, detection - a brief description of the viruses concerned, and present and future ways for their control. Experts from India, Nigeria, UK, USA, France, Germany, Peru, Japan, Australia, Netherlands, Venezuela, Kazakhstan and Israel (many of them from the International Research Institutions) have contributed chapters to this book.

The book provides a fascinating overview about current and sophisticated developments in applied entomology that are powered by molecular biology and that can be summarized under a novel term: insect biotechnology. By analogy with the application of powerful molecular biological tools in medicine (red biotechnology), plant protection (green biotechnology) and industrial processing (white biotechnology), insect biotechnology (yellow biotechnology) provides novel tools and strategies for human welfare and nutrition. Insect Biotechnology has emerged as a prospering discipline with considerable economic potential, and encompasses the use of insect model organisms and insect-derived molecules in medical research as well as in modern plant protection measures.

Precise regulation of gene expression in both time and space is vital to plant growth, development and adaptation to biotic and abiotic stress conditions. This is achieved by multiple mechanisms, with perhaps the most important control being exerted at the level of transcription. However, with the recent discovery of microRNAs another ubiquitous mode of gene regulation that occurs at the post-transcriptional level has been identified. MicroRNAs can silence gene expression by targeting complementary or partially complementary mRNAs for degradation or translational inhibition. Recent studies have revealed that microRNAs play fundamental roles in plant growth and development, as well as in adaptation to biotic and abiotic stresses. This book highlights the roles of individual miRNAs that control and regulate diverse aspects of plant processes.

Many fungi and bacteria that associate with plants are potentially harmful and can cause disease, while others enter into mutually beneficial sym bioses. Co-evolution of plants with pathogenic and symbiotic microbes has lead to refined mechanisms of reciprocal recognition, defense and counter defense. Genes in both partners determine and regulate these mechanisms. A detailed understanding of these genes provides basic biological insights as well as a starting point for developing novel methods of crop protection against pathogens. This volume deals with defense-related genes of plants and their regulation as well as with the genes of microbes involved in their interaction with plants. Our discussion begins at the level of populations and addresses the complex interaction of plant and microbial genes in multigenic disease resistance and its significance for crop protection as compared to mono genic resistance (Chap. 1). Although monogenic disease resistance may have its problems in the practice of crop protection, it is appealing to the experimentalist: in the so-called gene-for-gene systems, single genes in the plant and in the pathogen specify the compatibility or incompatibility of an interaction providing an ideal experimental system for studying events at the molecular level (Chaps. 2 and 4). Good progress has been made in identifying viral, bacterial, and fungal genes important in virulence and host range (Chaps. 3-6). An important aspect of plant-microbe interactions is the exchange of chemical signals. Microbes can respond to chemical signals of plant origin."

The molecular mechanisms which determine whether the cells of a multicellular organism will live or commit suicide have become a popular field of research in biology during the last decade. Cell death research in the plant field has also been expanding rapidly in the past 5 years. This special volume of Plant Molecular Biology seeks to bring together examples of a diverse array of experimental approaches in a single volume. From the differentiation of tracheary elements in vascular plants to the more specialized cell death model of the aleurone in cereals, this volume will bring the reader up-to-date with the characterization of different plant model systems that are currently being studied. This endeavor should complement general overviews of plant cell death mechanisms that have been published elsewhere by providing more detailed information on various aspects of this field to interested graduate students and more senior biologists alike.

From February 24 -28, 1992 an international symposium on Durability of Disease Resistance was held at the International Agricultural Centre in Wageningen, the Netherlands. The symposium, organized by the Department of Plant Breeding of Wageningen Agricultural University and the Centre for Plant Breeding and Repro duction Research, CPRO-DLO, was part of the DGIS funded programme Durable Resistance in Developing Countries. Without any form of prevention or protection nearly all crops will be seriously or even severely damaged by a range of pathogens. In modern agriculture man has been able to control many if not most pathogens using i) pesticides, ii) phyto sanitary methods such as control of seed and plant material in order to start a crop disease free, iii) agronomic measures such as crop rotation, iv) disease resis tance or combinations of these measures. Over the years the use of pesticides has increased enormously and so did the pro blems associated with pesticide use, such as environmental pollution and building of resistance and tolerance to these pesticides in the pathogens. The use of resis tance too increased strongly over the years and here too problems arose.

To cope with the increasing problems created by agrochemicals such as plant fertilizers, pesticides and other plant protection agents, biological alternatives have been developed over the past years. These include biopesticides, such as bacteria for the control of plant diseases, and biofertilizer to improve crop productivity and quality. Especially plant growth promoting rhizobacteria (PGPR) are as effective as pure chemicals in terms of plant growth enhancement and disease control, in addition to their ability to manage abiotic and other stresses in plants. The various facets of these groups of bacteria are treated in this Microbiology Monograph, with emphasis on their emergence in agriculture. Further topics are Bacillus species that excrete peptides and lipopeptides with antifungal, antibacterial and surfactant activity, plant-bacteria-environment interactions, mineral-nutrient exchange, nitrogen assimilation, biofilm formation and cold-tolerant microorganisms.

Biological control offers a promising alternative to chemical control which can have adverse environmental implications. This volume contains 16 articles describing the most modern topics in biocontrol of plant pathogens, including risk analysis for the release of microbial antagonists, genetic engineering and application of tissue culture.

For 31 years, the North American Symbiotic Nitrogen Fixation Conference (for merly Rhizobium Conference) has been a forum for scientists and graduate students to discuss their research advances, extending from basic aspects to agricultural appli cations, and dealing with topics ranging from bacterial genetics and metabolism to plant genetics and physiology. Nitrogen fixation, being a major life-supporting process on this planet, has attracted the interest of researchers for more than one century. Nitrogen fixation is responsible for the conversion of "inert" dinitrogen (N ) gas from the atmos z phere into usable ammonia, replacing the fixed nitrogen constantly being lost to the atmosphere by the denitrification process. Worldwide agricultural productivity is deter mined by the availability of fixed nitrogen in all its forms, which the continually increas ing human population depends upon for survival. An international momentum is developing in the use of biofertilizers to improve legume and non-legume crop yields and in the study of genomics in this area. New studies are being undertaken in several laboratories to study novel nitrogen-fixing systems, including non-legume crops. The North American Conferences on Symbiotic Nitrogen Fixation have periodically chronicled the advances in our knowledge of this area. For the first time, this conference was held in Mexico. Thus, all three North Amer ican countries have been hosts for this event. This year conference brought nearly 200 scientists from 18 different countries presenting lectures and over 80 posters.

In 1992 a Concerted Action Programme (CAP) was initiated by Peter Sijmons with the purpose of intensifying collaborations between 16 European laboratories working on plant-parasitic nematodes. The four-year programme entitled Resistance mechanisms against plant-parasitic nematodes' focused on molecular aspects of the interaction between sedentary nematodes and plants on the model system Arabidopsis and on novel resistance strategies. Funding was provided mainly for exchange visits between collaborating laboratories and for the organization of annual meetings. During the last annual meeting which was held in May 1996 in Toledo, Spain, Carmen Fenoll initiated the production of this volume. The book presents a series of up-to-date reviews, each written by one of the participating laboratories, which include the scientific progress achieved in the frame of this CAP but are by no means limited in scope to this work.

When I received an invitation to attend the International Symposium on Lethal Yellowing being organised by the Centro de Investigacion Cientifica de Yucatan (CICy), I was excited and a little nostalgic. During the 1970s, a series of similar symposia had been held under the auspices of the loosely-constituted "International Council on Lethal Yellowing" (ICL Y). These were the years when the MLO cause for L Y was first proposed, a vector was found, the disease was racing across mainland Florida, USA and it was suspected of having jumped to Cozumel. Analogous diseases were also reported to be spreading in Africa and elsewhere. The ICL Y meetings, held approximately every two years, proved to be an immensely valuable forum for all involved in the research and control of L Y. They attracted a very wide cross-section of scientists and practitioners working on L Y, on related diseases, and on palms in general. Many participants of those ICL Y meetings also attended this CICY Symposium. Unfortunately, during the 1980s, as countries learned to live with L Y, most of the national and international funding for L Y research dried up, and so did ICL Y. The present symposium is the only international meeting to have been devoted to L Y since the last meeting of rCLY in 1979. Its convening in Merida is timely.

The protection of agricultural crops, forest, and man and his domestic animals from annoyance and damage by various kinds of pests remains a chronic problem. As we endeavor to improve pro duction processes and to develop more effective and acceptable tactics for achieving this protection, we must give high priority to all potentially useful techniques for the control and management of insects. Pest control is recognized as an acceptable and necessary part of modern agriculture. Methods employed vary greatly and tend to reflect compromises involving 3 determining factors: technological capability, economic feasibility, and social acceptability. How ever, these factors are also subject to change with time since each involves value judgments that are based on available information, cost, benefit considerations, the seriousness of the pest problem, and the political climate. Whatever method is chosen, energy resources continue to dwindle under the impact of increasing popu lation, and it is inevitable that greater reliance must be placed upon renewable resources in pest management. One alternative is the use of a pest management method that uses the energy of the pest's own biomass to fuel a self-perpetuating control system. The use of biological control agents for the control of pests has long been an integral part of the pest management strategy in crop production and forestry and in the protection of man and animals. The importance and unique advantages of the method are well recognized; numerous treatises deal with accomplishments and methodologies."

Plants live in a constantly changing environment from which they cannot physically escape. Plants therefore need signalling and response mechanisms to adapt to new local conditions. The ef?cacy of such mechanisms underlies the plant performance during stress and therefore also impacts greatly on agricultural productivity. M- ulation of ion channel activity not only provides a means for rapid signal generation 2+ but also allows adjustment of cellular physiology. For example, Ca permeable ion 2+ channels can transduce environmental stimuli into Ca -encoded messages which can modify the gene expression. Furthermore, ion channel activity is essential to control cellular ion homeostasis that impacts on plant responses to drought, salinity, pathogens, nutrient de?ciency, heavy metals, xenobiotics and other stresses. This volume focuses on the crucial roles of different types of ion channel in plant stress responses. Functions of ion channels are discussed in the context of mechanisms to relay external and endogenous signals during stress and as mechanisms to regulate cellular ion homeostasis and enzymatic activities in the context of biotic and abiotic stress. The chapters presented cover cation and anion channels located in various cellular compartments and tissues.

Only 14 years have passed since the first publication appeared which implicated mycoplasmas as agents of plant disease. The diseases them selves have been known for much longer; indeed clover phyllody, a typical example, was described in the seventeenth century, well before any animal mycoplasma diseases had been documented. The early history of plant mycoplasmas is described in Chapter 2 and one obvious conclusion to be drawn from the frustrating experiences of the earlier workers is that the experimental methods at their disposal were simply inadequate for the task. Progress in science depends critically upon the development of new methods. Although important advances have been made in plant and insect mycoplasmology, notably in the discovery of spiroplasmas, many intractable problems remain. Most plant myco plasmas cannot yet be cultured in vitro, and their natural plant habitat, the phloem, is one of the most difficult plant tissues for the experi menter to handle, placing severe restrictions on the type of experiments which can be performed in vivo. It is clear that radically new methods may be required to solve these problems. A survey of the progress which has been made shows that application of techniques from a wide range of disciplines has been necessary. A successful individual or group of workers must possess the skills of a plant pathologist, a plantsman, a plant physiologist, a light-and electron microscopist, a bacteriologist, a biochemist, an immunologist, an ento mologist, a virologist and a molecular geneticist."

Abstract This chapter defines food security as the condition reached when a nation's population has access to sufficient, safe, and nutritious food to meet its dietary needs and food preferences. It stresses China's importance to global food security because of its population size. The chapter introduces the contents of the volume and then treats briefly food security in ancient and dynastic (211 bc-1912) China. It examines environmental stressors, such as population growth, natural disasters, and insect pests as well as imperial responses (for example, irrigation, flood control, storage and transportation systems). The chapter also briefly int- duces the Republican era (1912-1949) and compares environmental stressors and government responses then to those of the imperial period. Keywords Food system * Food security * Food production regions * Environmental stressors (Population growth * Natural disasters * Insect pests and Plant diseases * Deforestation * Climate change) * Irrigation systems * Flood control * Grand Canal 1. 1 The Problem of Food Security and Environmental Change Food is the material basis to human survival, and in each nation-state, providing a system for the development, production, and distribution of food and its security is a primary national objective. Many forces have influenced the food security of peoples since ancient times, with particular challenges from natural disasters (floods, famines, drought, and pestilence) and growing populations globally.

The past decade is probably unparalleled as a period of dynamic changes in the crop protection sciences-entomology, plant pathology, and weed science. These changes have been stimulated by the broad-based concern for a quality environment, by the hazard of intensified pest damage to our food and fiber production systems, by the inadequacies and spiraling costs of conventional crop protection programs, by the toxicological hazards of unwise pesticide usage, and by the negative interactions of independent and often narrowly based crop protection practices. During this period, the return to ecological approaches in crop protection was widely accepted, first within entomology and ultimately within the other crop protection and related disciplines. Integrated pest management is fast becoming accepted as the rubric describing a crop pro tection system that integrates methodologies across all crop protection dis ciplines in a fashion that is compatible with the crop production system. Much has been written and spoken about "integrated control" and "pest management," but to date no treatise has been devoted to the concept of "in tegrated pest management" in the broadened context as described above. Most of the manuscripts in this volume were developed from papers presented in a symposium at the annual meeting of the American Association for the Ad vancement of Science held in San Francisco in February, 1974. In arranging that symposium, the editors involved plant pathologists, entomologists, and weed scientists."