In a presentation to the Linnean Society of London in November 1831, the Scottish botanist Robert Brown (perhaps better known for his discovery of Brownian motion) mentioned almost as an afterthought that in orchid epidermal cells, a single "circular areola" could be seen, a "nucleus of the cell as perhaps it might be termed." Thus, the term "nucleus" (from Latin nucleus or nuculeus, "little nut" or kernel) was born for the compartment of the eukaryotic cell that contains the maj- ity of genetic information. One hundred and seventy-seven years later, we know that the nucleus is the site where genetic information is stored in the form of DNA, and where it is protected from damage, duplicated, divided, recombined, repaired, and "expressed." For the latter, the genetic information is faithfully transcribed from DNA to RNA, then released from the nucleus into the surrounding cytoplasm. Most likely translated into polypeptide chains, the information re-enters the nucleus in the form of diverse proteins that function in the processes listed above.

Mongolia is an expansive land-locked country, tilted by tectonic forces to the North, that experiences extremes of continental climate. Moisture-carrying wind currents are scarce so that the land has extended highs and lows in its environment. Culturally the people are mostly nomadic, having been sustained for centuries by an economy based on domestic livestock grazing. There is a saying that, As the noses go, so goes Mongolia', referring to the domesticated grazing noses of sheep, goats, camels, yaks or horses, and wild ungulates such as gazelles. The vast fenceless steppes of Mongolia furnish the vegetation for grazing. With such extremes in climate it is clear that the vegetation must be resilient and dynamic to cope with the dictates of its extremely harsh environments. Pollen profiles from lakes, plant macrofossils and other data over the last 15,000 years show the dynamic nature of Mongolian vegetation. Currently Mongolian society is experiencing much human-driven economic development which increases pressure on its vegetation. The Great Khural Laws of 1995 forcefully addressed such environmental concerns with the expanded establishment of National Reserves and Parks. But continued effort and vigilance must be expended to insure that Mongolian society will continue to be sustained by its vegetation. This book highlights work such as conserving and restoring plant diversity in various ecosystems and makes recommendations for sustaining the vegetation basis of the nomadic Mongolian society.

This timely reference provides an in-depth and up-to-date study of the most important groups of plant secondary compounds. No other work features such detailed diagrams of the biosynthetic pathways leading to the most important groups of secondary metabolites, as well as the structures of major types of compounds, their distribution in various taxonomic groupings of plants, and the evolutionary and ecological roles of these compounds. Plant Secondary Metabolism presents a basic understanding of the origin of the compounds, the nature of the precursors involved, and the basic reactions, mechanisms, and stereochemistry. The origin of groups of secondary metabolites is linked to evolutionary principles, and their biological activity is viewed in a context of chemical ecology. Topics are treated comprehensively, enabling the reader to understand not only a particular group of compounds, but also how each group fits into the whole. In addition, the text allows readers to systematically survey various secondary metabolites and gain a quick working knowledge which can be applied to problems in a particular field. Those researchers and students who will be most intrigued by this publication's broad overview on plant secondary metabolites come from a diverse range of disciplines, including agronomy, anthropology, biochemistry, biology, botany, chemistry, ecology, entomology, food science, forestry, geology, horticulture, pharmacognosy, plant biology, plant sciences, toxicology, and zoology.

Plant Cell Morphogenesis: Methods and Protocols provides a collection of experimental techniques used in current research on the cellular aspects of plant morphogenesis. Methods and techniques include contemporary takes on classical light microscopy and histochemistry through automated microscopy applications, use of advanced optical tools, quantitative image analysis, study of cellular dynamics of apical meristems, specialized electron microscopy techniques, and methods used to study specific model plant cell types and protocols for using heterologous expression in yeast to study cell morphogenesis genes. Individual chapters in the highly successful Methods in Molecular Biology series format are written by expert researchers in the field and include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step laboratory protocols, and key tips on troubleshooting and avoiding known pitfalls.

Natural and agro-ecosystems are frequently exposed to natural or synthetic substances, which, while they have no direct nutritional value or significance in metabolism, may negatively affect plant functioning. These, xenobiotics, may originate from both natural (fires, volcano eruptions, soil or rock erosion, biodegradation) and anthropogenic (air and soil pollution, herbicides) sources. And, while affected plants have only a limited number of possibilities for avoiding accumulation of these compounds, they do exhibit several enzymatic reactions for detoxification including oxidation, reduction, hydrolysis and conjugation reactions. In agro-ecosystems in particular these mechanisms have great significance in relation to herbicide detoxification and tolerance. In this volume an international group of experts present an overview of the nature and distribution of organic xenobiotics, including their uptake, effects on plant functioning and detoxification mechanisms. The particular significance of glutathione S-transferases in bio-indication and bio-monitoring, and in the detoxification of volatile organic air pollutants and herbicides is evaluated, and their potential significance in phytoremediation and bioaccumulation will be discussed. This volume will be of interest to a wide audience, from graduate students to senior researchers in a wide range of disciplines including plant ecology, plant biochemistry, agriculture and environmental management. It will also be of practical interest to environmentalists, policy makers and resource managers.

Traditional plant physiological ecology is organism centered and provides a useful framework for understanding the interactions between plants and their environment and for identifying characteristics likely to result in plant success in a particular habitat. This book focuses on extending concepts from plant physiological ecology as a basis for understanding carbon, energy, and biogeochemical cycles at ecosystem, regional, and global levels.
This will be a valuable resource for researchers and graduate students in ecology, plant ecophysiology, ecosystem research, biometerology, earth system science, and remote sensing.
Key Features
* The integration of metabolic activities across spatial scales, from leaf to ecosystem
* Global constraints and regional processes
* Functional units in ecological scaling
* Models and technologies for scaling

The second edition has been completely revised and has incorporated significant changes that have occurred in wood anatomy over the past years. Richly illustrated with light and scanning electron micrographs, Comparative Wood Anatomy clearly introduces dicotyledon wood in terms of cell types and their variations, pertinent literature, taxonomic distribution of characteristics, terminology, methods for preparation and ecological and evolutionary significance of. wood features. From reviews of the previous edition: "In synthesis, this book presents itself as an immensely valuable exposé on comparative wood anatomy and its bearing on systematic, ecological and evolutionary aspects of dicotyledon wood." (Wood Science and Technology) "This book is recommended to all who are interested in a modern, stimulating, competent, and well illustrated work." (Holzforschung)

Many agricultural crops worldwide, especially in semi-arid climates, suffer from iron deficiencies. Among plants sensitive to iron deficiency are apples, avocado, bananas, barley, beans, citrus, cotton, grapes, peanuts, pecans, potatoes, sorghum, soybeans, and numerous ornamental plants. Deficiencies are usually recognized by chlorotic, in new leaves and are typically found among sensitive crops grown in calcareous or yellowed, interveinal areas soils which cover over 30% of the earth's land surface. Iron deficiency may lead, in extreme cases, to complete crop failure. In intensive agriculture on calcareous soils, iron often becomes a major limiting nutrient for optimal crop production, thus, correction of iron deficiency is required. Various chemicals and practices are available. They are, however, costly and do not always result in a complete remedy of the deficiency. Crucial questions relative to the cost-benefit equation such as the recovery rate of plants and the long-term fertilizing effect have not yet been resolved. The complexity of iron nutrition problems requires an understanding of the chemistry of iron oxides in soils, of the chemistry of both natural and synthetic chelates, of rhizosphere microbiology and biochemistry, and of the physiological involvement of the plant in iron uptake and transport.

An understanding of the mechanisms by which plants perceive environmental cues, both physical and chemical, and transduce the signals that influence specific expression of genes, is an area of intensive scientific research. With the completion of the genome sequence of Arabidopsis it is understood now that a larger number of genes encode for proteins involved in signalling cascades and transcription factors. In this volume, different chapters deal with plant receptors, second messengers like calcium ions, phosphoinositides, salicylic acid and nitrous oxide, calcium binding proteins and kinases. In addition to dealing with the response of plants to light, hormones, pathogens, heat, etc. on cellular activity, work currently going on in apoptosis, cell division, and plastid gene expression is also covered in this book.

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.

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Water is a paramount factor in determining the distribution of species on a global basis. The responses and adaptations of a species to water stress are critical for its success in any environmental niche. The deserts of the Middle East provide an excellent example of the harsh conditions to which plants are subjected.This volume elucidates the adaptations of these plants in order to sustain their life and reproduce to continue their survival. Topics covered include climate aridity and topographic influence on plant life in the deserts, the role of plants in the lives of the Bedouins, the concept of adaptation, its purposes and causes, adaptations that promote increased water uptake and reduction of water output, as well as those which help the plants to tolerate and/or resist the drought, escaping drought and adaptation to desiccation, and the mechanisms by which halophytes can tolerate and/or resist salinity.

Plant hormones play a crucial role in controlling the way in which plants growand develop. Whilemetabolism providesthepowerand buildingblocks for plant life, it is the hormones that regulate the speed of growth of the individual parts and integrate these parts to produce the form that we recognize as a plant. In addition, theyplayacontrolling role inthe processes of reproduction. This book is a description ofthese natural chemicals: how they are synthesizedand metabolized; howthey work; whatwe knowoftheir molecular biology; how we measure them; and a description ofsome ofthe roles they play in regulating plant growth and development. Emphasis has also been placed on the new findings on plant hormones deriving from the expanding use ofmolecular biology as a tool to understand these fascinating regulatory molecules. Even at the present time, when the role of genes in regulating all aspects of growth and development is considered of prime importance, it is still clear that the path of development is nonetheless very much under hormonal control, either via changes in hormone levels in response to changes in gene transcription, or with the hormones themselves as regulators ofgene transcription. This is not a conference proceedings, but a selected collection ofnewly written, integrated, illustrated reviews describing our knowledge of plant hormones, and the experimental work that is the foundation of this knowledge.

Molecular biology, particularly molecular genetics, is among the newest and most powerful approach in modern photosynthesis research. Development of molecular biology techniques has provided new methods to solve old problems in many biological disciplines. Molecular biology has its greatest potential for contribution when applied in combination with other disciplines, to focus not just on genes and molecules, but on the complex interaction between them and the biochemical pathways in the whole organism. Photosynthesis is surely the best studied research area in plant biology, making this field the foremost candidate for successfully employing molecular genetic techniques. Already, the success of molecular biology in photosynthesis has been nothing short of spectacular. Work performed over the last few years, much of which is sum marized in this volume, stands in evidence. Techniques such as site-specific mutagenesis have helped us in examining the roles of individual protein domains in the function of multiunit complexes such as the enzyme ribulose-l,5-bisphos phate carboxylase/oxygenase (RUBISCO) and the oxygen evolving photo system (the photosystem II). The techniques of molecular biology have been very important in advancing the state of knowledge of the reaction center from the photosynthetic bacteria whose structure has been elegantly deduced by H. Michel and 1. Deisenhofer from the X-ray studies of its crystals."

Well designed, constructed and maintained reinforced or prestressed concrete structures are generally very durable. In aggressive environments though, corrosion of steel can be a significant problem and structures such as bridges, industrial buildings and those subjected to marine conditions can be particularly at risk. Over the last decade there has been fast growing interest in reinforcing concrete with fibre reinforced plastic materials which cannot rust or deteriorate like steel. This proceedings of the Second International RILEM Symposium on the subject, held in Ghent, August 1995, deals with a wide range of non-metallic materials and opens up possibilities of lighter, more durable structures. The contributions by leading international researchers and design engineers are divided into parts covering material development and properties, bond behaviour of FRP elements, structural behaviour of reinforced and prestressed concrete members, rehabilitation and strengthening, and design methods and applications. This complete overview of knowledge on the subject will provide an essential update for structural engineers, concrete specialists and researchers into materials and structures.

Plants provide a source of survival for all life on this planet. They are able to capture solar energy and convert it into food, feed, wood and medicines. Though sessile in nature, over many millions of years, plants have diversified and evolved from lower to higher life forms, spreading from sea level to mountains, and adapting to different ecozones. They have learnt to cope with challenging environmental conditions and various abiotic and biotic factors. Plants have also developed systems for monitoring the changing environment and efficiently utilizing resources for growth, flowering and reproduction, as well as mechanisms to counter the impact of pests and diseases and to communicate with other biological systems, like microbes and insects. This book discusses the "awareness" of plants and their ability to gather information through the perception of environmental cues, such as light, gravity, water, nutrients, touch and sound, and stresses. It also explores plants' biochemical and molecular "computing" of the information to adjust their physiology and development to the advantage of the species. Further, it examines how plants communicate between their different organs and with other organisms, as well as the concepts of plant cognition, experience and memory, from both scientific and philosophical perspectives. Lastly, it addresses the phenomenon of death in plants. The epilogue presents an artist's view of the beauty of the natural world, especially plant "architecture". The book provides historical perspectives, comparisons with animal systems where needed, and general biochemical and molecular concepts and themes. Each chapter is selfcontained, but also includes cross talk with other chapters to offer an integrated view of plant life and allow readers to appreciate and admire the functioning of plant life from within and without. The book is a tribute by the Editor to his students, colleagues and co-workers and to those in whose labs he has worked.

Plant-Microbe Interactions, Volume 1 Many plant-microbe interactions have agronomic importance because of either beneficial (e.g., nitrogen fixation or biocontrol) or detrimental (e.g., pathogen esis) effects. Although these systems have been the subjects of scientific re search for many years, recently there has been a tremendous increase in our knowledge of them. The increases in this research have followed a similar general increase in plant science research. Classical plant science research disciplines (e.g., agronomy, breeding, plant physiology, systematics, etc.) have been affected by an increased focus on molecular biology. These new technologies, as well as advances in other areas, have the effect of blurring the traditional borders between research disciplines. Another factor influencing the development of this research is the increased attention given to environmental issues. These concerns have been brought about by debate over the release of genetically modified organisms and the general concern over environmental quality. Thus, research areas focused on plant-microbe interactions are presently in a period of great excitement and growth that shows every sign of continuing far into the future. As in most research areas, the rate of advance and breadth of disciplines involved in the study of plant-microbe interactions make it impossible for the average researcher or student to stay abreast of the primary scientific literature."

Phytochemicals from medicinal plants are receiving ever greater attention in the scientific literature, in medicine, and in the world economy in general. For example, the global value of plant-derived pharmaceuticals will reach $500 billion in the year 2000 in the OECD countries. In the developing countries, over-the-counter remedies and "ethical phytomedicines," which are standardized toxicologically and clinically defined crude drugs, are seen as a promising low cost alternatives in primary health care. The field also has benefited greatly in recent years from the interaction of the study of traditional ethnobotanical knowledge and the application of modem phytochemical analysis and biological activity studies to medicinal plants. The papers on this topic assembled in the present volume were presented at the annual meeting of the Phytochemical Society of North America, held in Mexico City, August 15-19, 1994. This meeting location was chosen at the time of entry of Mexico into the North American Free Trade Agreement as another way to celebrate the closer ties between Mexico, the United States, and Canada. The meeting site was the historic Calinda Geneve Hotel in Mexico City, a most appropriate site to host a group of phytochemists, since it was the address of Russel Marker. Marker lived at the hotel, and his famous papers on steroidal saponins from Dioscorea composita, which launched the birth control pill, bear the address of the hotel."

Sequencing projects have revealed the presence of at least several hundred receptor kinases in a typical plant genome. Receptor kinases are therefore the largest family of primary signal transducers in plants, and their abundance suggests an immense signaling network that we have only just begun to uncover. Recent research findings indicate that individual receptor kinases fulfill important roles in growth and development, in the recognition of pathogens and symbionts or, in a few examples, in both growth and defense. This volume will focus on the roles of receptor kinases, their signaling pathways, and the ways in which these important signaling proteins are regulated.

Advances In Plant Nutrition, Volume Three, is the latest edition to Tinker's and Lauchli's series on major research efforts in plant nutrition. It synthesizes both basic and applied information in such areas as soil-plant relations, nutritional physiology, and plant nutrition technology. This combination of both fundamental and applied topics is a thorough and substantial coverage of plant nutrition, and will supplement the first two volumes. Researchers in agriculture, plant physiology, botany, forestry, and soil science will find this an invaluable resource, as will industrial and commercial producers of fertilizers who wish to be up to date on relevant topics. This comprehensive work contains six papers by experts in the field. The first essay discusses the difficult area of measuring intercell material flow via membranes, while the second explains chlorine as both a plant nutrient and osmotic balancing ion. The role of root exudates in nutrient acquistion is the topic of the third paper; plant nutrition in flood soil is the basis for the fourth. The next essay addresses how plants adopt different growth strategies in the often nutrient-poor natural environment. Finally, the background of leaf analysis systems is explored.

Lipids in Photosynthesis provides readers with a comprehensive view of the structure, function and genetics of lipids in plants, algae and bacteria, with special emphasis on the photosynthetic apparatus in thylakoid membranes. This volume includes the historical background of the field, as well as a full review of our current understanding of the structure and molecular organization of lipids and their role in the functions of photosynthetic membranes. The physical properties of membrane lipids in thylakoid membranes and their relationship to photosynthesis are also discussed. Other topics include the biosynthesis of glycerolipids and triglycerides; reconstitution of photosynthetic structures and activities with lipids; lipid-protein interactions in the import of proteins into chloroplasts; the development of thylakoid membranes as it relates to lipids; genetic engineering of the unsaturation of membrane glycerolipids, with a focus on the ability of the photosynthetic machinery to tolerate temperature stress; and the involvement of chloroplast lipids in the reactions of plants upon exposure to stress. This book is intended for a wide audience and should be of interest to advanced undergraduate and graduate students and to researchers active in the field, as well as to those scientists whose fields of specialization include the biochemistry, physiology, molecular biology, biophysics and biotechnology of membranes.

With the predicted increase of the human population and the subsequent need for larger food supplies, root health in crop plants could play a major role in providing sustainable highly productive crops that can cope with global climate changes. While the essentiality of roots and their relation to plant performance is broadly recognized, less is known about their role in plant growth and development. Root Genomics examines how various new genomic technologies are rapidly being applied to the study of roots, including high-throughput sequencing and genotyping, TILLING, transcription factor analysis, comparative genomics, gene discovery and transcriptional profiling, post-transcriptional events regulating microRNAs, proteome profiling and the use of molecular markers such as SSRs, DArTs, and SNPs for QTL analyses and the identification of superior genes/alleles. The book also covers topics such as the molecular breeding of crops in problematic soils and the responses of roots to a variety of stresses.

Nutrient Use Efficiency in Plants: Concepts and Approaches is the ninth volume in the Plant Ecophysiology series. It presents a broad overview of topics related to improvement of nutrient use efficiency of crops. Nutrient use efficiency (NUE) is a measure of how well plants use the available mineral nutrients. It can be defined as yield (biomass) per unit input (fertilizer, nutrient content). NUE is a complex trait: it depends on the ability to take up the nutrients from the soil, but also on transport, storage, mobilization, usage within the plant, and even on the environment. NUE is of particular interest as a major target for crop improvement. Improvement of NUE is an essential pre-requisite for expansion of crop production into marginal lands with low nutrient availability but also a way to reduce use of inorganic fertilizer.

With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences.

Genetic erosions in plant cell cultures, especially in chromosome number and ploidy level, have now been known for over 25 years. Until the mid -1970ssuch changes were consideredundesirable and thereforediscarded because the main emphasis wason clonal propagation and genetic stability of cultures. However, since the publication on somaclonal variation by Larkin and Scowcroft (1981) there has been a renewed interest to utilize these in vitro obtained variations for crop improvement. Studies conduc- ted during the last decade have shown that callus cultures, especially on peridical subculturing over an extended period of time, undergo morpho- logical and genetic changes, i. e. polyploidy, aneuploidy, chromosome breakage, deletions, translocations, gene amplification, inversions, muta- tions, etc. In addition, there are changes at the molecular and biochemical levelsincluding changes in the DNA, enzymes,proteins, etc. Suchchanges are now intentionally induced, and useful variants are selected. For instance in agricultural crops such as potato, tomato, tobacco, maize, rice and sugarcane, plants showing tolerance to a number of diseases, viruses, herbicides and salinity, have been isolated in cell cultures. Likewise induction of male sterility in rice, and wheat showing various levels of fer- tility and gliadin, have been developed in vitro. These academic excercises open new avenues for plant breeders and pathologists. Another area of tremendous commercial importance in the pharmaceuti- cal industry is the selection of cell lines showing high levels of medicinal and industrial compounds. Already high shikonin containing somaclones in Lithospermum are being used commercially.

The genetic work that has been carried out with volume, and especially in Section V 'Germplasm crop plants indicates that many nutritional charac- resources and creation of genotypes for specific teristics are independently inherited and could be environmental including low input systems', is selected for a breeding program. evident. This can be considered as genuine progress This volume presents the proceedings of the in the direction of an effective use of nutrients by 'Third International Symposium on Genetic plants. Aspects of Plant Mineral Nutrition' held in We look forward to more advances in our un- Braunschweig 1988, and demonstrates the wide derstanding of the mechanisms involved in the acceptance that cultivars respond differently to nutrient efficiency of crop plants and in the nutritional and stress factors. An improved re- development and improvement of screening sponse of cultivars to nutrients and stress con- techniques at the Fourth Symposium to be held in ditions is accessible via screening, selection and Australia in 1991. breeding of the available plant genetic resources and will help to reduce the inputs and to protect the N. EI Bassam environment. M.Dambroth The contribution of the plant breeders in this B. c. Loughman XI N. El Bassam et al. (Eds.), Genetic aspects a/plant mineral nutrition, 1-7. PLSO PN 122 (c) 1990 Kluwer Academic Publishers.