Charles E. Hess Department of Environmental Horticulture University of California Davis, CA 95616 Research in the biology of adventitious root formation has a special place in science. It provides an excellent forum in which to pursue fundamental research on the regulation of plant growth and development. At the same time the results of the research have been quickly applied by commercial plant propagators, agronomists, foresters and horticulturists (see the chapter by Kovar and Kuchenbuch, by Ritchie, and by Davies and coworkers in this volume). In an era when there is great interest in speeding technology transfer, the experiences gained in research in adventitious root formation may provide useful examples for other areas of science. Interaction between the fundamental and the applied have been and continue to be facilitated by the establishment, in 1951, of the Plant Propagators' Society, which has evolved into the International Plant Propagators' Society, with active programs in six regions around the world. It is a unique organization which brings together researchers in universities, botanical gardens and arboreta, and commercial plant propagators. In this synergistic environment new knowledge is rapidly transferred and new ideas for fundamental research evolve from the presentations and discussions by experienced plant propagators. In the past 50 years, based on research related to the biology of adventitious root formation, advances in plant propagation have been made on two major fronts.

Proceedings of the First International Symposium held in Dallas, Texas, April 18-22, 1993

This book contains the majority of the presentations of the Second International Symposium on the Biology of Root Formation and Development that was hcld in Jerusa lem, Israel, June 23---28, 1996. Following the First Symposium on the Biology of Adventi tious Root Formation, held in Dallas. USA, 1993, we perceived the need to include all kinds of roots, not only the shoot-borne ones. The endogenous signals that control root formation. and the subsequent growth and development processes, are very much alike, re gardless of the sites and sources of origin of the roots. Therefore, we included in the Sec ond Symposium contributions on both shoot-borne (i.e., adventitious) roots and root-borne (i.e., lateral) roots. Plant roots have remained an exciting and an intriguing field of sciencc. During thc years that followed the first symposium, an exceptional proliferation of interest in root biology has developed, associated with the intensive research activity in this field and the contemporary developments in the understanding of root function and development. New methods have been applied, and old ideas and interprctations werc rccxamined. Alto gether, it became necessary to update our viewpoints and to expand them.

Since the first edition of our book "Tissue Culture in Fores try" in 1982 we have witnessed remarkable advances in cell and tissue culture technologies with woody perennials. In addition to forest biologists in government, industry, and universities, we now have molecular biologists, genetic engineers, and biochemists using cell and tissue cultures of woody species routinely. There fore, the time has come for an update of the earlier edition. In our present effort to cover new developments we have expanded to three volumes: 1. General principles and Biotechnology 2. Specific Principles and Methods: Growth and Development 3. Case Histories: Gymnosperms, Angiosperms and Palms The scientific barriers to progress in tree improvement are not so much lack of foreign gene expression in plants but our current inabili ty to regenerate plants in true-to-type fashion on a mas sive and economic scale. To achieve this in the form of an appro pr iate biotechnology, cell and tissue culture will increasing ly require a better understanding of basic principles in chemistry and physics that determine structural and functional relationships among molecules and macromolecules (proteins, RNA, DNA) within cells and tissues. These principles and their relationship with the culture medium and its physical environment, principles of clonal propagation, and genetic variation and ultrastructure are discussed in volume one.

This volume illustrates the complex root system, including the various essential roles of roots as well as their interaction with diverse microorganisms localized in or near the root system. Following initial chapters describing the anatomy and architecture as well as the growth and development of root systems, subsequent chapters focus on the various types of root symbiosis with bacteria and fungi in the rhizosphere. A third section covers the physiological strategies of roots, such as nitrate assimilation, aquaporins, the role of roots in plant defense responses and in response to droughts and salinity changes. The book’s final chapters discuss the prospects of applied engineering of roots, i.e., inventing new root structures or functions through genetic modification, but also with conventional breeding and manipulation of root symbionts. The budding field of root engineering is expected to promote a second green revolution.

Introduces readers to the chemical biology of plant biostimulants This book brings together different aspects of biostimulants, providing an overview of the variety of materials exploited as biostimulants, their biological activity, and agricultural applications. As different groups of biostimulants display different bioactivity and specificity, advances in biostimulant research is illustrated by different examples of biostimulants, such as humic substance, seaweed extracts, and substances with hormone-like activities. The book also reports on methods used to screen for new biostimulant compounds by exploring natural sources. Combining the expertise of internationally-renowned scientists and entrepreneurs in the area of biostimulants and biofertilisers, The Chemical Biology of Plant Biostimulants offers in-depth chapters that look at: agricultural functions and action mechanisms of plant biostimulants (PBs); plant biostimulants from seaweed; seaweed carbohydrates; and the possible role for electron shuttling capacity in elicitation of PB activity of humic substances on plant growth enhancement. The subject of auxins is covered next, followed closely by a chapter on plant biostimulants in vermicomposts. Other topics include: exploring natural resources for biostimulants; the impact of biostimulants on whole plant and cellular levels; the impact of PBs on molecular level; and the use of use of plant metabolites to mitigate stress effects in crops. Provides an insightful introduction to the subject of biostimulants Discusses biostimulant modes of actions Covers microbial biostimulatory activities and biostimulant application strategies Offers unique and varied perspectives on the subject by a team of international contributors Features summaries of publications on biostimulants and biostimulant activity The Chemical Biology of Plant Biostimulants will appeal to a wide range of readers, including scientists and agricultural practitioners looking for more knowledge about the development and application of biostimulants.

This detailed volume provides diverse elegant methods, complemented with existing protocols, which are optimized for the current needs in plant root biology as well as for use in plant species other than Arabidopsis thaliana. The collection covers methods ranging from genetic screens, phenotypic analysis, and cell biology methods to systems biology tools and genome-wide approaches. The collection contains a range of complexity from fundamental methods for quantification of different root developmental processes to complex methods that require sophisticated equipment. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, Root Development: Methods and Protocols serves as a valuable tool for plant biologists specialized in root development, from beginners to experienced researchers in the field.