Does perception provide us with direct and unmediated access to the world around us? The so-called 'argument from illusion ' has traditionally been supposed to show otherwise: from the subject's point of view, perceptual illusions are often indistinguishable from veridical perceptions; hence, perceptual experience, as such, cannot provide us with knowledge of the world, but only with knowledge of how things appear to us. Disjunctive accounts of perceptual experience, first proposed by John McDowell and Paul Snowdon in the early 1980s and at the centre of current debates in the philosophy of perception, have been proposed to block this argument. According to the traditional view, a case of perception and a subjectively indistinguishable illusion or hallucination can exemplify what is fundamentally the same kind of mental state even though they differ in how they relate to the non-mental environment. In contrast, according to the disjunctive account, the concept of perceptual experience should be seen as essentially disjunctive, encompassing (at least) two distinct kinds of mental states, namely genuinely world-involving perceptions and mere appearances. This book presents seven recent essays on disjunctivism first published in two special issues of Philosophical Explorations: An International Journal for the Philosophy of Mind and Action.

This book provides a comprehensive review of all aspects of the molecular and cell biology of abscisic acid (ABA) metabolism, transport and signal transduction, covering our current understanding of ABA as well as research trends. The agricultural significance of ABA metabolism, transport and signal transduction is also discussed. The phytohormone ABA regulates many aspects of plant development and plays a central role in plant adaptation to environmental stresses. Over the past few decades, considerable advances have been made in the study of ABA metabolism, transport and signal transduction, greatly deepening our understanding of the underlying mechanisms of ABA function at the molecular, cell and whole-plant level and helping us improve crops' environmental tolerance. This book provides a valuable resource for researchers and advanced students interested in plant biology and agriculture.

This book results from a symposium on the theme of 'The Physiology and Biochemistry of Plant Productivity' which was held at the University of Calgary from July 14-18, 1980, and was jointly sponsored by the Canadian Society of Plant Physiologists and the International Association of Plant Physiologists. The subject matter of the book deals with various aspects of nitrogen and carbon metabolism, their interrelationships and interdependence. The topics covered in the chapters highlight various interesting and important lines of research that are in progress. There is no attempt to provide a comprehensive coverage of the basic physiological knowledge upon which this research depend- important references are to be found at the end of each chapter, however, and the reader will be able to pursue these as necessary. An introductory chapter by Dr. R.G.S. Bidwell (winner of the C.S.P.P. Gold Medal in 1979) considers some implications of plant physiological research and the aims and responsibilities of plant physiologists. In the next two chapters Drs. J. Rigaud and L.E. Schrader (with R.J. Thomas) elaborate on current research on nitrate metabolism and nitrogen fixation, and how an understanding of these phenomena might be usefully applied towards the manipulation of plants to improve productivity. Dr. J.S.

Tropical climates, which occur between 23 Degrees30'N and S latitude (Jacob 1988), encompass a wide variety of plant communities (Hartshorn 1983, 1988), many of which are diverse in their woody floras. Within this geographic region, temperature and the amount and seasonality of rainfall define habitat types (UNESCO 1978). The F AO has estimated that there 1 are about 19 million km of potentially forested area in the global tropics, of which 58% were estimated to still be in closed forest in the mid-1970s (Sommers 1976; UNESCO 1978). Of this potentially forested region, 42% is categorized as dry forest lifezone, 33% is tropical moist forest, and 25% is wet or rain forest (Lugo 1988). The species diversity of these tropical habitats is very high. Raven (1976, in Mooney 1988) estimated that 65% of the 250,000 or more plant species of the earth are found in tropical regions. Of this floristic assemblage, a large fraction are woody species. In the well-collected tropical moist forest of Barro Colorado Island, Panama, 39. 7% (481 of 1212 species) of the native phanerogams are woody, arborescent species (Croat 1978). Another 21. 9% are woody vines and lianas. Southeast Asian Dipterocarp forests may contain 120-200 species of trees per hectare (Whitmore 1984), and recent surveys in upper Amazonia re corded from 89 to 283 woody species ~ 10 cm dbh per hectare (Gentry 1988). Tropical communities thus represent a global woody flora of significant scope.

Epigenetics commonly acts at the chromatin level modulating its structure and consequently its function in gene expression and as such plays a critical role in plant response to internal and external cues. This book highlights recent advances in our understanding of epigenetic mechanisms as a major determinant through which internal and external signals, such as those occurring during hybridization, flowering time, reproduction and response to stress, communicate with plant cells to bring about activation of multiple nuclear processes and consequently plant growth and development. The outcome of these processes may persist for generations long after the initial cues have expired and may contribute to plant evolution.

Every year between three and four hundred papers are published on the topic of insulin action. This extraordinary publication rate prevents any author from includ ing an exhaustive bibliography in any review or book. Perhaps due to this there is no single text that attempts to cover the effects and the mechanism of action of insulin. This book is such an attempt. I intend to present a review of the physiological effects of insulin, the pathology of defects in the action of insulin, and the current views on the mechanism of action of this hormone. I make no apology for the fact that the bibliography will not be extensive and that the amount of experimental detail and data discussed will be kept to a relevant minimum. This book is not intended for the expert in the field, but for the second- or third-year undergraduate and graduate student of medicine, biochemistry, physiology or related disciplines, and will be valuable as a reference source for research workers. The book is presented as a guide, a summary of the ideas and facts; it will present a reader with a foretaste of a fascinating and ever-changing field. I have attempted to be up-to-date with published research work. Any significant contributions to the field not included in the first draft have been added as footnotes. I assume a basic knowledge of the metabolic pathways of carbohydrates, fats and proteins."

Plant innate immunity is a potential surveillance system of plants and is the first line of defense against invading pathogens. The immune system is a sleeping system in unstressed healthy plants and is activated on perception of the pathogen-associated molecular patterns (PAMP; the pathogen s signature) of invading pathogens. The PAMP alarm/danger signals are perceived by plant pattern-recognition receptors (PRRs). The plant immune system uses several second messengers to encode information generated by the PAMPs and deliver the information downstream of PRRs to proteins which decode/interpret signals and initiate defense gene expression. This book describes the most fascinating PAMP-PRR signaling complex and signal transduction systems. It also discusses the highly complex networks of signaling pathways involved in transmission of the signals to induce distinctly different defense-related genes to mount offence against pathogens."

Plants cannot move away from their environments. As a result, all plants that have survived to date have evolved sophisticated signaling mechanisms that allow them to perceive, respond, and adapt to constantly changing environmental conditions. Among the many cellular processes that respond to environmental changes, elevation of calcium levels is by far the most universal messenger that matches primary signals to cellular responses. Yet it remains unclear how calcium, a simple cation, translates so many different signals into distinct responses - how is the "specificity" of signal-response coupling encoded within the calcium changes? This book will attempt to answer this question by describing the cellular and molecular mechanisms underlying the coding and decoding of calcium signals in plant cells.

The nutritive endosperm of angiosperms is mankind 's most important source of food, livestock feed and industrial raw material. This book is the first comprehensive overview of the developmental and molecular biology of endosperm. The text covers cereal endosperm development from fertilization to maturity, including molecular and cell biology of the syncytial phase. It also goes into the cellularization process and cell fate specification of the embryo surrounding region cells, the basal transfer cells, the starchy endosperm and aleurone cells.

The germ plasm of numerous plant species, especially those of forest trees, some agricultural crops, and medicinal plants, is endangered and threatened with extinction. This depletion of germplasm pools and the shrinkage of naturally occurring genetic resources have caused international concern. Conventionally, the germplasm of plants is conserved through seeds, tubers, roots, corms, rhizomes, bulbs, cuttings, etc. However, the germ plasm of a number of trees and plantation crops (such as coconut, cocao, coffee, oil palm, rubber, mango, horse chestnut, etc. ) cannot be preserved since their seed are short-lived (recalcitrant). Likewise, germplasm of vegetatively propagated crops (such as potato and cassava) cannot be stored on a long term basis and has to be grown and multiplied periodically in nurseries and fields. The plants are thus exposed to unpredictable weather conditions and diseases, with the result that instances are known where entire genetic stocks are lost. Therefore, unconventional methods are being developed for the storage and international exchange of germplasm. For this purpose in vitro cultures have been employed, but they can only enable short-to medium term preservation; moreover, cell cultures upon repeated subculture undergo genetic erosion. In view of the recent developments in the in vitro induction of genetic variability through somaclonal variation, somatic hybridization, recombinant DNA technology, etc., new methods need to be employed for the storage of desirable cultures. In this regard freeze preservation of cells in liquid nitrogen (-196 0q, like that of semen, enables long-term storage, theoretically, for an indefinite period of time."

This book provides detailed and comprehensive information on oxidative damage caused by stresses in plants with especial reference to the metabolism of reactive oxygen species (ROS). In plants, as in all aerobic organisms, ROS are common by-products formed by the inevitable leakage of electrons onto O2 from the electron transport activities located in chloroplasts, mitochondria, peroxisomes and in plasma membranes or as a consequence of various metabolic pathways confined in different cellular loci. Environmental stresses such as heat, cold, drought, salinity, heavy-metal toxicity, ozone and ultraviolet radiation as well as pathogens/contagion attack lead to enhanced generation of ROS in plants due to disruption of cellular homeostasis. ROS play a dual role in plants; at low concentrations they act as signaling molecules that facilitate several responses in plant cells, including those promoted by biotic and abiotic agents. In divergence, at high levels they cause damage to cellular constituents triggering oxidative stress. In either case, small antioxidant molecules and enzymes modulate the action of these ambivalent species.

In plant cells, the plasma membrane is a highly elaborated structure that functions as the point of exchange with adjoining cells, cell walls and the external environment. Transactions at the plasma membrane include uptake of water and essential mineral nutrients, gas exchange, movement of metabolites, transport and perception of signaling molecules, and initial responses to external biota. Selective transporters control the rates and direction of small molecule movement across the membrane barrier and manipulate the turgor that maintains plant form and drives plant cell expansion. The plasma membrane provides an environment in which molecular and macromolecular interactions are enhanced by the clustering of proteins in oligimeric complexes for more efficient retention of biosynthetic intermediates, and by the anchoring of protein complexes to promote regulatory interactions. The coupling of signal perception at the membrane surface with intracellular second messengers also involves transduction across the plasma membrane. Finally, the generation and ordering of the external cell walls involves processes mediated at the plant cell surface by the plasma membrane. This volume is divided into three sections. The first section describes the basic mechanisms that regulate all plasma membrane functions. The second describes plasma membrane transport activity. The final section of the book describes signaling interactions at the plasma membrane. These topics are given a unique treatment in this volume, as the discussions are restricted to the plasma membrane itself as much as possible. A more complete knowledge of the plasma membrane's structure and function is essential to current efforts to increase the sustainability of agricultural production of food, fiber, and fuel crops.

Sixty years ago at the Waite Agricultural Research Institute, G. Samuel, a plant pathologist, and C. S. Piper, a chemist, published their conclusion that the cause of roadside take-all, a disease of oats, was manganese deficiency. This report, together with the concurrent and independent studies of W. M. Carne in Western Australia were the first records of manganese deficiency in Australia and came only six years after McHargue's paper which is generally accepted as the final proof of the essentiality of this element. There must have been a few doubts for some people at the time, however, as the CAB publication, 'The Minor Elements of the Soil' (1940) expressed the view that further evidence to this effect was provided by Samuel and Piper. Their historic contributions are recognised by the International Symposium on Manganese in Soils and Plants as it meets on the site of their early labours to celebrate the 60th anniversary. This year Australians also acknowledge 200 years of European settlement in this country and so the Symposium is both a Bicentennial and a diamond jubilee event which recognises the impact of trace elements on agricultural development in Australia. In a broader sense, a symposium such as this celebrates, as it reviews, the efforts of all who over the ages have contributed to our knowledge of manganese in soils and plants.

Chloroplast development is a key feature of leaf developmental program. Recent advances in plant biology reveal that chloroplasts also determine the development, the structure and the physiology of the entire plant. The books, published thus far, have emphasized the biogenesis of the organelle, but not the events associated with the transformation of the mature chloroplast to the gerontoplast during senescence. This book, with 28 chapters, is unique because it describes how the chloroplast matures and how it is subsequently transformed to become the gerontoplast during senescence, a process required for nutrient recycling in plants. This book includes a state-of-the-art survey of the current knowledge on the regulation and the mechanisms of chloroplast development.Some of the chapters critically discuss the signaling process, the expression potential of plastid DNA, the interaction of cellular organelles, and the molecular mechanisms associated with the assembly and the disassembly of organellar complexes and finally the modulation of chloroplast development by environmental signals."

The formation of roots is in some respects one of the least fundamentally understood of all plant functions. Propagation by cuttings is the aspect that will occur first to most gardeners and horticulturists, and it is certainly the most useful application. But any observant traveller in the tropics can notice that some trees have the habit of forming roots in the air. Climbers like Cissus bear long fine strings of roots hanging down. Pandanus trees tend to have stout aerial roots issuing from the bases of the long branches, while the tangle of roots around the trunk of many of the Ficus species is characteristic. In Ficus bengalensis, in particular, stout cylindrical roots firmly embedded in the ground from a height of 3 to 5 meters give support to the long horizontal branches, enabling them to spread still further. In the big old specimen at Adyar near Madras, the spread of these branches all around the tree, each with a strong root growing out every few meters, makes a shaded area under which meetings of almost 5000 people are sometimes held. The history of how the formation of roots on stem cuttings was found to be under hormonal control is worth repeating here.

The plasma membrane is at once the window through which the cell senses the environment and the portal through which the environment influences the structure and activities of the cell. Its importance in cellular physiology can thus hardly be overestimated, since constant flow of materials between cell and environment is essential to the well-being of any biological system. The nature of the materials mov ing into the cell is also critical, since some substances are required for maintenance and growth, while others, because of their toxicity, must either be rigorously excluded or permitted to enter only after chemical alteration. Such alteration frequently permits the compounds to be sequestered in special cellular compartments having different types of membranes. This type of homogeneity, plus the fact that the wear and tear of transmembrane molecular traffic compels the system to be constantly monitored and repaired, means that the membrane system of any organism must be both structurally complex and dy namic. Membranes have been traditionally difficult to study because of their fragility and small diameter. In the last several decades, however, remarkable advances have been made because of techniques permit ting the bulk isolation of membranes from homogenized cells. From such isolated membranes have come detailed physical and chemical analyses that have given us a detailed working model of membrane. We now can make intelligent guesses about the structural and func tional interactions of membrane lipids, phospholipids, proteins, sterols and water.

A collection of papers that comprehensively describe the major areas of research on lipid metabolism of plants. State-of-the-art knowledge about research on fatty acid and glycerolipid biosynthesis, isoprenoid metabolism, membrane structure and organization, lipid oxidation and degradation, lipids as intracellular and extracellular messengers, lipids and environment, oil seeds and gene technology is reviewed. The different topics covered show that modern tools of plant cellular and molecular biology, as well as molecular genetics, have been recently used to characterize several key enzymes of plant lipid metabolism (in particular, desaturases, thioesterases, fatty acid synthetase) and to isolate corresponding cDNAs and genomic clones, allowing the use of genetic engineering methods to modify the composition of membranes or storage lipids. These findings open fascinating perspectives, both for establishing the roles of lipids in membrane function and intracellular signalling and for adapting the composition of seed oil to the industrial needs. This book will be a good reference source for research scientists, advanced students and industrialists wishing to follow the considerable progress made in recent years on plant lipid metabolism and to envision the new opportunities offered by genetic engineering for the development of novel oil seeds.

The NATO Advanced Research Workshop (ARW) on "Regulation of Enzymatic Systems Detoxifying Xenobiotics in Plants" intended to provide a forum to scientists from academia, industry, and govemment for discussing and critically assessing recent advances in the field of xenobiotic metabolism in plants and for identifying new directions for future research. Plants function in a chemical environment made up of nutrients and xenobiotics. Xenobiotics (foreign chemicals) are natural or synthetic compounds that can not be utilized by plants for energy-yielding metabolism. Plants may be exposed to xenobiotics either deliberately, due to their use as pesticides or accidentally, from industrial, agricultural, and other uses. Plants, like most other organisms, evolved a remarkable battery or metabolic reactions to defend themselves against the potentially toxic effects of xenobiotics. The main enzymatic reactions utilized by plants for xenobiotic detoxification include oxidation, reduction, hydrolysis and conjugation with glutathione, sugars (e.g., glucose), and amino acids. Eventually, xenobiotic conjugates are converted to insoluble bound residues or to secondary conjugates, which are deposited in the vacuole of plant cells.

The beginnings of human civili zation can be traced back to the time , ne- ly 12 ,000 years ago , when th e early humans gradually ch anged from a life of hunting and gathering food , to producing food. This beginning of pri- tive agriculture ensured a dependable supply of food , and fostered the living together of people in groups and the development of s o c i e ty. During th is time, plant s e e ds were recognized a s a valuable s o ur c e of food and nutrition , and began to be used for growing plants for food. Ever s i n c e , plant seeds have played an important role in the development of the human civilization . Even today, s e e ds of a few crop s p e c i e s , s uc h as the cereals and legume s, are the primary s o u r c e of most human food , and the predominant commodity in international agriculture. Owing to their great importance as food for human s and in international trade , seeds have been a favorite object of s t u d y by developmental biologists and physiologi sts , nutritionist s and chem i sts . A wealth of useful information i s available on th e biology of seed s .

Historically, scientists and laymen have regarded salinity as a hazar dous, detrimental phenomenon. This negative view was a principal reason for the lack of agricultural development of most arid and semi arid zones of the world where the major sources of water for biological production are saline. The late Hugo Boyko was probably the first scientist in recent times to challenge this commonly held, pessimistic view of salinity. His research in Israel indicated that many plants can be irrigated with saline water, even at seawater strength, if they are in sandy soil - a technique that could open much barren land to agriculture. This new, even radical, approach to salinity was clearly enunciated in the book he edited and most appropriately entitled 'Salinity and Aridity: New Approaches to Old Problems' (1966). A decade later, three members of the United States National Science Foundation (NSF), Lewis Mayfield, James Aller and Oskar Zaborsky, formulated the 'Biosaline Concept'; namely, that poor soils, high solar insolation and saline water, which prevail in arid lands, should be viewed as useful resources rather than as disadvantages, and that these resources can be used for non-traditional production of food, fuels and chemicals. The First International Workshop on Biosaline Research was con vened at Kiawah Island, South Carolina, in 1977 by A. San Pietro."

This book was developed from the proceedings of the 2nd North American Tan nin Conference held in Houghton, Michigan, June, 1991. The objective of this con ference was to bring together people with a common interest in plant polyphenols and to promote interdisciplinary interactions that will lead to a bet ter understand ing of the importance of these substances. Another objective of this conference was to extend the 'tannin family' by making special efforts to encourage participation by scientists outside the United States, obtain more coverage of the hydrolyzable tannins, and further broaden the scope of coverage from the initial concentration on forestry and forest products. Com parison of the contents of this book with 'Chemistry and Significance of Condensed Tannins' that resulted from the proceedings of the 1st North American Tannin Conference shows the degree that these objectives were met. In developing the second conference, care was taken to assure that this book extends rather than duplicates the coverage of the first conference. Therefore, the two books should be taken together to obtain an up to date coverage of the broad area of chemistry and significance of plant polyphenols. Our thanks go to the authors who so kindly contributed chapters and so pa tiently responded to our requests. We thank the Conference Assistance Staff of Michigan Technological University for their help in planning and conducting the conference."

Metal contamination is an increasing ecological and eco-toxicological risk. Understanding the processes involved in metal mobilization, sorption and mineralization in soils are key features for soil bioremediation.

Following an introduction to the physical, chemical and biological components of contaminated soils, various chapters address the interactions of soil, microorganisms, plants and the water phase necessary to transfer metals into biological systems. These include topics such as potential hazards at mining sites; rare earth elements in biotic and abiotic acidic systems; manganese redox reactions; biomineralisation, uranium in seepage water; metal-resistant streptomycetes; mycorrhiza in re-forestation; metal (hyper)accummulation in plants; microbial metal uptake; and their potential for bioremediation.

This book will be of interest to soil biologists, geologists and chemists, researchers and graduate students, as well as consulting companies and small enterprises involved in bioremediation.

Rinie Hofstra has been a member of the Department of Plant Physiology, University of Groningen, the Netherlands, for 24 years. The nearer we came to 31 March 1985, her 65th birthday, the more we all realized how we would miss her - not only scientifically, but also socially. She left her mark on both research and teaching, always with an open mind and willing to change. After her PhD Thesis on 'Nitrogen Metabolism in Tomato Plants' she first continued working in that field, but soon started a joint project with the Department of Plant Ecology on hemiparasites. She then became involved in carbon metabolism, which resulted in her giving a Biotrop Course on C /C metabolism in 3 4 Indonesia. Her own research group, originally working on 'Nitrogen Metabolism', soon embraced 'Energy and Nitrogen Metabolism', as the research on respiration became more and more important. In running her group she showed all sides of her person. She used to stimulate and encourage everyone around her and to integrate the various lines of research. At the same time she always had an open mind for the opinion of all members of her group. And together they regularly criticized and evaluated the various projects and decided how to continue.

This book summarizes our current knowledge on belowground defence strategies in plants by world-class scientists actively working in the area. The volume includes chapters covering belowground defence to main soil pathogens such as Fusarium, Rhizoctonia, Verticillium, Phytophthora, Pythium and Plasmodiophora, as well as to migratory and sedentary plant parasitic nematodes. In addition, the role of root exudates in belowground plant defence will be highlighted, as well as the crucial roles of pathogen effectors in overcoming root defences. Finally, accumulating evidence on how plants can differentiate beneficial soil microbes from the pathogenic ones will be covered as well. Better understanding of belowground defences can lead to the development of environmentally friendly plant protection strategies effective against soil-borne pathogens which cause substantial damage on many crop plants all over the world. The book will be a useful reference for plant pathologists, agronomists, plant molecular biologists as well as students working on these and related areas.

Environmental stresses represent the most limiting factors for agricultural productivity. Apart from biotic stress caused by plant pathogens, there are a number of abiotic stresses such as extremes in temperature, drought, salinity, heavy metals and radiation which all have detrimental effects on plant growth and yield. However, certain plant species and ecotypes have developed various mechanisms to adapt to such stress conditions. Recent advances in the understanding of these abiotic stress responses provided the impetus for compiling up-to-date reviews discussing all relevant topics in abiotic stress signaling of plants in a single volume. Topical reviews were prepared by selected experts and contain an introduction, discussion of the state of the art and important future tasks of the particular fields.