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.

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.

This book discusses the recent advancements in the role of various biomolecules in regulating root growth and development. Rhizobiology is a dynamic sub discipline of plant science which collates investigations from various aspects like physiology, biochemistry, genetic analysis and plant–microbe interactions. The physiology and molecular mechanisms of root development have undergone significant advancements in the last couple of decades. Apart from the already known conventional phytohormones (IAA, GA, cytokinin, ethylene and ABA), certain novel biomolecules have been considered as potential growth regulators or hormones regulating plant growth and development. Root phenotyping and plasticity analysis with respect to the specific functional mutants of each biomolecule shall provide substantial information on the molecular pathways of root signaling. Special emphasis provides insights on the tolerance and modulatory mechanisms of root physiology in response to light burst, ROS generation, agravitrophic response, abiotic stress and biotic interactions. Root Apex Cognition: From Neuronal Molecules to Root-Fungal Networks and Suberin in Monocotyledonous Crop Plants: Structure and Function in Response to Abiotic Stresses” are available open access under a Creative Commons Attribution 4.0 International License via link.springer.com. Chapters “Root Apex Cognition: From Neuronal Molecules to Root-Fungal Networks and Suberin in Monocotyledonous Crop Plants: Structure and Function in Response to Abiotic Stresses” are available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.

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 third edition of a standard resource, this book offers a state-of-the-art, multi-disciplinary presentation of plant roots. It examines structure and development, assemblage of root systems, metabolism and growth, stressful environments, and interactions at the rhizosphere. Reflecting the explosion of advances and emerging technologies in the field, the book presents developments in the study of root origin, composition, formation, and behavior for the production of novel pharmaceutical and medicinal compounds, agrochemicals, dyes, flavors, and pesticides. It details breakthroughs in genetics, molecular biology, growth substance physiology, biotechnology, and biomechanics.

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.

Root Development is an extremely exciting new title in Blackwell Publishing's Annual Plant Reviews Series (Series Editor Profesor Jeremy Roberts). The book consists of contributions from author groups based at many of the World's formeost laboratories working in the root development area. The book's editor Tom Beeckman, himself very well known and respected for his work in this area, has drawn together an exceptional set of core cutting edge reviews of the subject, providing a state of the art reference tool for all those researching in this area.

The decade since the publication of the third edition of this volume has been an era of great progress in biology in general and the plant sciences in particular. This is especially true with the advancements brought on by the sequencing of whole genomes of model organisms and the development of "omics" techniques. This fourth edition of Plant Roots: The Hidden Half reflects these developments that have transformed not only the field of biology, but also the many facets of root science. Highlights of this new edition include: The basics of root research and their evolution and role in the global context of soil development and atmosphere composition New understandings about roots gained in the post-genomic era, for example, how the development of roots became possible, and the genetic basis required for this to occur The mechanisms that determine root structure, with chapters on cellular patterning, lateral root and vascular development, the molecular basis of adventitious roots, and other topics Plant hormone action and signaling pathways that control root development, including new chapters on strigolactones and brassinosteroids Soil resource acquisition from agricultural and ecological perspectives Root response to stress, with chapters that address the impact of the genomic revolution on this topic Root-rhizosphere interactions, from beneficial microorganisms to detrimental nematodes Modern research techniques for the field and the lab Each chapter not only presents a clear summation of the topic under discussion, but also includes a vision of what is to be expected in the years to come. The wide coverage of themes in this volume continues the tradition that makes this work recognized as a fundamental source of information for root scientists at all levels.