Due to their sessile lifestyle, plants need to efficiently adapt to changing environmental conditions during their life cycle. Nutrient acquisition from the soil has to be able to adapt to considerable fluctuations in concentrations to ensure adequate distribution between tissues, cells and organelles. The storage and retrieval of nutrients, metabolites or toxic substances in vacuoles plays an important part in cellular homeostasis in plants. The long-range transport and maintenance of turgor is critically dependent on the availability of water and rate of evaporation, while at the same time photosynthetic products have to be transported to all plant parts. As a result plants contain a large number of ATP-dependent pumps and secondary transporters that, in order to adapt to the changing environment, need to be regulated by a complex network of sensing and signaling mechanisms. Plants share many basic elements of signal transduction with animals, but also contain plant-specific signaling molecules and mechanisms. In this volume, the role of transporters and pumps in the regulation of movement, long-range transport and compartmentalization of water, solutes, nutrients and classical signaling molecules is highlighted, and the function, regulation and membrane-transporter interaction and their roles in plant signaling controlling plant physiology and development are discussed.

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.

Over recent years, progress in micropropagation has not been as rapid as many expected and, even now, relatively few crops are produced commercially. One reason for this is that the biology of material growing in vitro has been insufficiently understood for modifications to standard methods to be made based on sound physiological principles. However, during the past decade, tissue culture companies and others have invested considerable effort to reduce the empirical nature of the production process. The idea of the conference `Physiology, Growth and Development of Plants and Cells in Culture' (Lancaster, 1992) was to introduce specialists in different areas of plant physiology to micropropagators, with the express aims of disseminating as wide a range of information to as large a number of participants as possible, and beginning new discussions on the constraints and potentials affecting the development of in vitro plant production methods. This book is based on presentations from the conference and has been divided into two main sections, dealing with either aspects of the in vitro environment -- light, nutrients, water, gas -- or with applied aspects of the culture process -- morphogenesis, acclimation, rejuvenation, contamination.

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.

The double helix architecture of DNA was elucidated in 1953. Twenty years later, in 1973, the discovery of restriction enzymes helped to create recombinant DNA molecules in vitro. The implications of these powerful and novel methods of molecular biology, and their potential in the genetic manipulation and improvement of microbes, plants and animals, became increasingly evident, and led to the birth of modern biotechnology. The first transgenic plants in which a bacterial gene had been stably integrated were produced in 1983, and by 1993 transgenic plants had been produced in all major crop species, including the cereals and the legumes. These remarkable achievements have resulted in the production of crops that are resistant to potent but environmentally safe herbicides, or to viral pathogens and insect pests. In other instances genes have been introduced that delay fruit ripening, or increase starch content, or cause male sterility. Most of these manipulations are based on the introduction of a single gene - generally of bacterial origin - that regulates an important monogenic trait, into the crop of choice. Many of the engineered crops are now under field trials and are expected to be commercially produced within the next few years. The early successes in plant biotechnology led to the realization that further molecular improvement of plants will require a thorough understanding of the molecular basis of plant development, and the identification and character ization of genes that regulate agronomically important multi genic traits.

Achievements today in plant biotechnology have already surpassed all previous expectations. Plant biotechnology, integrated with classical breeding, is now on the verge of creating the evergreen revolution' to solve the world's envisaged tripled demand for food, agricultural commodities and natural products. New biotechnologies are being continuously adapted to agricultural practices, opening new vistas for plant utilization. Plant biotechnology is changing the plant scene in three major areas: (1) growth and development control (vegetative, generative and propagation), (2) protecting plants against the ever-increasing threats of abiotic and biotic stress, (3) expanding the horizons by producing specialty foods, biochemicals and pharmaceuticals. The potential for improving plant and animal productivity and their proper use in agriculture relies largely on newly-developed DNA biotechnology and molecular markers. These techniques enable the selection of successful genotypes, better isolation and cloning of favorable traits, and the creating of transgenic organisms of importance to agriculture. These areas were extensively discussed at the 9th international congress of the International Association of Plant Tissue Culture and Biotechnology, Plant Biotechnology and In Vitro Biology in the 21st Century', which was held in Jerusalem in June 1998. The present book of proceedings contains the variety of scientific achievements and techniques that were presented: Basic and Applied Aspects of Growth, Development and Differentiation; Genetic Manipulations: Transformation and Gene Expression, Hybridization, Haploidization and Mutagenesis; Genetic Stability and Instability, Selection and Variability; Regulation of Primary and Secondary Metabolism; Model Systems: Cell Cycle, Transport and Signal Transduction; Biotechnology for Plant Protection: Abiotic and Biotic Stress; Biotechnology for Crop Improvement: Yield, Quality and Production of Valuable Substances; Novel Micropropagation Methods; New Markets and Commercial Applications; Intellectual Property Rights.

Optical screening of excessive and potentially harmful solar radiation is an important photoprotective mechanism, though it has received much less attention in comparison with other systems preventing photooxidative damage to photoautotrophic organisms. This photoprotection in the form of screening appears to be especially important for juvenile and senescing plants as well as under environmental stresses-i.e. in situations where the efficiency of enzymatic ROS elimination, DNA repair and other 'classical' photoprotective systems could be impaired. This book represents an attempt to develop an integral view of optical screening-based photoprotection in microalgae and higher plants. Towards this end, the key groups of pigments involved in the screening of ultraviolet and visible components of solar radiation in microalgae and higher plants, and the patterns of their accumulation and distribution within plant cells and tissues, are described. Special attention is paid to the manifestations of screening pigment accumulation in the optical spectra of plants. It is also demonstrated that understanding these effects and their relationships to screening pigments' makeup and spectroscopy in plants provides valuable insights into the state of plants' long-term photoacclimation, as well as ample opportunities for the non-destructive quantification of screening pigments and the assessment of the efficiency of photoprotection providing by these pigments in situ.

Research in animals and plants is frequently 'departmentalized' and funded according to Kingdoms by granting bodies. The use of transgenes to address biological questions in all Kingdoms led us to propose to the Royal Society that fundamental and strategic studies in animals and plants involving trans genes should be presented in one meeting, rather than, as so often happens, in different scientific societies. The two-day Discussion Meeting held inJuly 1992, and reported here provided insights into how trans genes are being exploited to discover new knowledge in animals and plants. The papers were presented by leading investigators in the biological sciences, and the book reflects an experiment in interdisciplinarity which was declared a successful venture by the large crowd of participants and delegates. The transgenic area is one of high scientific interest and sporadic, yet intense biotechnological euphoria. This is dramatically illustrated among the following papers which show how genetic maps of animals and plants produce new knowledge of disease incidence in humans, and how the design of transgenes can result in biodegradable plastic in higher plants, human pharmaceutical proteins in livestock, or bacterial proteins in cotton crops to protect against insect damage.

Plant cell and tissue culture is a relevant area of experimental biology that has been developed for some decades to become an indispensable tool of plant biotechnology. Progress in this area, sometimes tumultuous, has been regularly recorded by the proceedings of the congresses of the International Association for Plant Tissue Culture which have been held every four years in several continents. This book reports plenary lectures, keynote lectures and invited oral presentations given at the last congress held in Florence. It is a useful reference guide both for established scientists and students on both traditional and emerging fields of plant biology. The following topics are covered: In vitro Culture and Plant Regeneration; Plant Propagation; Haploids; Somatic Hybridisation; Reproductive Systems; Genetic Variability; Gene Transfer; Organelles; Biotechnology of Tropical and Subtropical Species; Agronomic Traits; Somatic Embryogenesis; Meristems; Cell Surface; Growth Regulators; Reception and Transduction of Signals; Gene Expression under Extreme Conditions; Primary Metabolism; Secondary Metabolism; Transport; Large Scale Production.

Volumes I and 2 of this Plant Biotechnology series reviewed fundamental aspects of plant molecular biology and discussed production and analysis of the first generation of transgenic plants of potential use in agriculture and horticulture. These included plants resistant to insects, viruses and herbicides, which were produced by adding genes from other organisms. Realisation of the potential of plant breeding has led to a resurgence of interest in methods of altering the structure, composition and function of plant constituents, which represents an even greater challenge and offers scope for improving the quality of a wide range of agricultural products. This, in tum, has resulted in a re-evaluation of priorities and targets by industry. Volume 3 of this series considers the biochemical and gentic basis of the biosynthesis of plant products such as starch, lipids, carotenoids and cell walls, and evaluates the ways in which biosynthesis of these products can be modified for use in the food industries. Authors also cover the biosynthesis of rare secondary products and the function and application of proteins for plant protection and therapeutic use. The emphasis throughout is on the relationship between fundamen tal aspects of biosynthesis and structure-function relationships, and application of this knowledge to the redesigning and altering of plant products by molecular genetics."

Several fundamental advances were announced at the Seventh International Symposium on Molecular Plant--Microbe Interactions held in Edinburgh in 1994. These included the cloning and identification of plant resistance genes involved in recognition of pathogens; the description of genetically engineered plants with novel resistance to pathogens; characterization of the molecular basis of pathogenicity of fungal and bacterial plant pathogens; and the mechanisms of communication used during recognition between symbiotic rhizobia and their host legumes. Participants in the Symposium contributed a series of papers that represent the leading edge of research in this important area of plant and microbial science. These articles are brought together to form this book, which will be essential reading for research workers, advanced students and others interested in keeping abreast of this rapidly developing area.

The inflorescence of the monoecious maize plant is unique among the Gramineae in the sharp separation of the male and female structures. The male tassel at the terminus of the plant most often sheds pollen before the visual appearance of the receptive silks of th the female ear at a lateral bud, normally at the 10 leaf [I]. Earlier studies examined the ontogeny of the growing tissues beginning with the embryo in the kernel through to the obvious protuberances of the growing point as the kernel germinates. The differentiated developing soon-to-become tassel and the lateral bulges that develop into the ears on the lateral buds become apparent very early in the germinating kernel [2, 3, 46]. A certain number of cells are destined for tassel and ear development [8]. As the plant develops, there is a phase transition [\3, 16] from the vegetative lateral buds to the reproductive lateral buds. This change in phase has been ascribed to genotypic control as evidenced in the differences among different genotypes in the initiation of the reproductive [I]. The genetic control of tassel and ear initiation has been gleaned from anatomical observations. Lejeune and Bernier [I2] found that maize plants terminate the initiation of additional axillary meristems at the time of tassel initiation. This would indicate that the top-most ear shoot is initiated on the same day as the initiation of tassel development and this event signals the end of the undifferentiated growing point.

Plant Molecular Biology Manual (Second Edition) is an entirely new manual containing both fundamental and recently described techniques in the area of plant molecular biology. Designed for use in the research laboratory, the Plant Molecular Biology Manual presents detailed techniques in the areas of plant transformation, recombinant DNA and other nucleic acid manipulations, nuclear run-on and in vitro transcription systems, in situ hybridization and immunodetection systems, protein-nucleic acid interaction analyses, subcellular targeting of proteins in the plant cell, and gene tagging using T-DNA and transposons. This second edition contains more than 40 newly written chapters, including descriptions of subjects such as virus-mediated gene transfer, specialized Agrobacterium strains and T-DNA vectors, nuclear run-on and in vitro transcription systems, non-radioactive detection systems, characterization of transcription factors, nuclear protein targeting, and T-DNA and transposon mutagenesis, not previously described in the first edition.

In the field of plant analysis there is a confusing variety of methods and procedures, both for digestions and determinations. In many cases the digestion and the subsequent determination are interrelated. For example, a separate digestion is needed for trace elements in order to obtain determinable concentrations. The authors have chosen a design in which the digestion/extraction procedure is described in one chapter together with all determination procedures that may be carried out on that particular digest/extract. All the necessary information (such as standardizations) appears in appendices. As a consequence, several determination procedures are described two or three times, however, each based on a particular digestion or extraction method. Two types of determination procedure are described: manual and automated. Manual procedures are mainly used in research laboratories, whereas automated procedures are more frequently applied in routine laboratories. Both types of determinations can be used freely, provided that appropriate equipment is available. The determination procedures are only for inorganic components, usually elements. Besides, most procedures are designed to give a total content value of the element under consideration, regardless of the chemical structure in which it occurs in the plant. The Plant Analysis Manual is intended for the practicing (agricultural) chemist.

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.

This is the second volume in the series Nutrients in Ecosystems. Sulphur as an essential plant nutrient has received little attention. This is explained by the facts that sulphur was obviously in sufficient supply from the atmosphere, from soil and as a by-product in mineral fertilizers. Increases in the yield potential and thus in the nutrient requirement of modern crops, however, as well as remarkable changes in SO2 emissions by private households, power stations and industry, associated with legislative measures to reduce air and water pollution, have altered the situation to a large extent. In particular the public concerns about forest decline and pollution-induced climatic changes have initiated extensive research programs on the physiological functions of sulphur in plants, on the occurrence and plant availability of sulphur in agricultural and forest soils and on the chemistry of sulphur compounds in the tropo- and stratosphere. This book cannot be an encylcopedia of sulphur in all the media mentioned nor in all ecozones of the globe. However, it aims to give an overview of our present knowledge with a special focus on the sulphur situation in agrosystems of industrialised Western Europe. The ecological trends for sulphur observed in this region during recent decades are likely to be mirrored wherever industrialisation and urbanisation take place and where an increasing standard of living demands clean air, good drinking water and nutritious food. Agricultural production systems, therefore, require well-founded information on the actual sulphur nutrition and potential sulphur-fertilizer requirement of crops and soils respectively. It is hoped that this book will provide this information and will encourage further research where open questions still exist.

Considerable advances have been made in our understanding of the eukaryotic cell cycle at the molecular level over the past two decades or so, particularly in yeast and in animal systems. However, only in the past three or four years has progress been made in plants at the molecular level. The present volume brings together molecular biologists, cell biologists and physiologists to discuss this recent progress and how it relates to our understanding of the regulation of plant growth and development. The opening paper summarises the progress which has been made with fission yeast. Subsequent papers explore what is known about cell cycle control at the molecular level in plants, and about cell cycle regulation in specific physiological systems, ending with summary papers on cell division in roots and shoots. The book comprises up-to-date findings on a fundamental aspect of plant growth and development, and as such will be of particular interest to advanced undergraduates, postgraduates and research scientists in the fields of molecular biology, cell biology and physiology.

JACQUES S. BECKMANN & THOMAS C. OSBORN Extraordinary progress has been made in the analyses of the genetic structures of higher eukaryotic genomes. Only ten years elapsed between the initial proposals to use molecular DNA markers for the generation of a complete linkage map of the human genome [5, 17] and the first description of a 10 centimorgan map of one of its chromosomes [22], soon to be followed by others. The availability of molecular DNA markers, henceforth called genomic markers [for a review of their properties see 1, 2, 20], represents a milestone in genetics by providing the capacity for complete genetic coverage of all genomes. It is important to remember that the nature of the DNA polymorphism or of the specific method used to uncover it can be quite different for different marker loci. The genetic variation detected can be a result of a simple point mutation, a DNA insertion/deletion event, or a change in repeat copy number at some hypervariable DNA [11] or micro satellite [21] motif. Currently, the methods of detection can involve use of restriction endonucleases, nucleic acid hybridization, or DNA sequence amplification. Each of these sources of var iation and methods of detection can have utility for different applications. Furthermore, new approaches for the detection of DNA polymorphism are constantly emerging. The primary concern here is that the monitored poly morphism defines a genetic marker 'useful' for the desired application.

The symposium on "Zinc in Soils and Plants" is the third in a series which began with "Copper in Soils and Plants" in Perth in 1981 and continued with "Manganese in Soils and Plants" in Adelaide in 1988. The symP9sium brings together a series of valuable accounts of many aspects of the reactions of zinc in soils, the uptake, transport and utilization of zinc in plants, the diagnosis and correction of zinc deficiency in plants and the role of zinc in animal and human nutrition. I am grateful for the financial support provided by Grains Research and Development Corporation, Rural Industries Research and Development Corporation, Wool Research and Development Corporation, Ansett Australia, and Qantas Australian. I am most appreciative of the willingness of many scientists to act as referees: G S P Ritchie, R J Gilkes, N C Uren, K Tiller, BLeach, H Greenway, N E Longnecker, J F Loneragan, Z Rengel, C A Atkins, J W Gartrell, P J Randall, D G Edwards, R J Hannam, R J Moir, J E Dreosti, N Suttle, C L White, H Marschner, N Wilhelm, M McBride. All provided valuable comments on the manuscripts. Finally, I thank Mrs M Davison who provided excellent secretarial assistance. A.D. Robson September 1993 Chapter 1.

The subject of fruit ripening is one of vital interest and importance to the massive international fruit growing and fruit trade industries. This book is the definitive handbook on the subject, bringing together a vast wealth of important information from an experienced team of international contributors.

Higher eukaryotes are characterized by the allocation of distinct functions to numerous types of differentiated cells. Whereas in animals the well-defined, protected cells of the germ line separate early, germ cells in plants differentiate from somatic cells only after many cycles of mitotic division. Therefore somatic mutations in plants can be transmitted via the germ cells to the progeny. There is thus a clear need for somatic tissues to maintain their genetic integrity in the face of environmental challenges, and two types of interactions have been shown to play important roles in the conservation as well as flexibility of plant genomes: homologous recombination of repeated sequences and silencing of multiplied genes. Sensitive methods have been developed that allow greater insights into the dynamics of the genome. This book summarizes current knowledge and working hypotheses about the frequencies and mechanisms of mitochondrial, plastid, nuclear and viral recombination and the inactivation of repeated genes in plants. Despite rapid developments in the field, it is often not possible to provide final answers. Thus, it is an additional task of this book to define the open questions and future challenges. The book is addressed to scientists working on plant biology and recombination, to newcomers in the field and to advanced biology students.

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.

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.

Plant Production on the Threshold of a New Century describes and compares problems and frontier developments in the different sectors of plant production, integrating developments in basic plant sciences, crop science and socioeconomic science, leading to sustainable plant production. Hence the book formulates goals and constraints in policy, economy, production, environment and land use; indicates how these goals and constraints may be translated into farming styles and cropping systems; and describes how the fundamental plant sciences can contribute to the implementation of such farming styles and cropping systems.

Proceedings of the International Workshop on Gelidium held in Santander, Spain, September 3-8, 1991