Cytokinins

Cytokinins are hormones involved in all aspects of plant growth and development and are essential for in vitro manipulation of plant cells and tissues. Much information has been gathered regarding the chemistry and biology of cytokinins, while recent studies have focused on the genetics and cytokinin-related genes. However, other than proceedings of symposia, no single volume on cytokinins has been written. This book is the first of its kind, homing in on the key subject areas of cytokinin-chemistry, biosynthesis, metabolism, activity, function, genetics, and analyses. These areas are comprehensively reviewed in individual chapters by experts currently active in the field. In addition, a personal history on the discovery of cytokinin is presented by Professor Folke Skoog. This volume summarizes previous findings and identifies future research directions.

Cytokinins are hormones involved in all aspects of plant growth and development and are essential for in vitro manipulation of plant cells and tissues. Much information has been gathered regarding the chemistry and biology of cytokinins, while recent studies have focused on the genetics and cytokinin-related genes. However, other than proceedings of symposia, no single volume on cytokinins has been written. This book is the first of its kind, homing in on the key subject areas of cytokinin-chemistry, biosynthesis, metabolism, activity, function, genetics, and analyses. These areas are comprehensively reviewed in individual chapters by experts currently active in the field. In addition, a personal history on the discovery of cytokinin is presented by Professor Folke Skoog. This volume summarizes previous findings and identifies future research directions.

Cytokinins: Biosynthesis and Uses discusses ornamental pot plant productivity, which is negatively affected by the pot root restriction during both the nursery and post-transplant stages. Root restriction is a physical stress imposed on the root system when plants are grown in small containers, which leads to a pronounced decrease in root and shoot growth at both the transplant and pot stages. Next, the authors summarize most information available on the main environmental and hormonal factors that affect New Guinea Impatiens plant growth under commercial conditions and shows the high potentiality of exogenous cytokinin application in both the vegetative propagation industry and pot culture of ornamental plants. The closing chapter addresses how understanding plant responses to hormonal manipulation and the physiological mechanisms involved in transplantation will allow for reaching higher commercial yields in different vegetables.

In a number of recent biology meetings, plant growth factors have been a favorite topic. One may ask if a new colloquium devoted to the metab olism and the activities of cytokinins, considered at the molecular level, was really necessary and will add anything important to the previous contributions. As a matter of fact, the primary purpose of the organizers, of the French National Center of Scientific Research, and of the National In stitute of Agronomic Research which sponsored the colloquium was less the edition of a proceedings book than the desire to bring together a number of scientists who had made contributions towards solving prob· lems in cytokinin research and thereby to provide an opportunity for fruitful discussions without restrictions in the timetable. Indeed this primary target was attained. Moreover, important new fmdings and con clusions were presented by the participants that merited publication in the form ofthis book. It is beyond the scope of this foreword to adver tize or even to classify these new fmdings. We shall only mention a few of them. The reader will appreciate the contributions of those authors who worked hard to elucidate the biosynthetic pathways of natural cytokin ins.

Plant hormones have pivotal roles in the regulation of plant growth, development, and reproduction. Their signaling pathways are interconnected in a complex network, which provides plants with an enormous regulatory potential to rapidly adapt to their environment and to utilize their limited resources for growth and survival in a cost-efficient manner. Auxin is a hormone molecule whose activity levels are most important for its regulatory roles during plant cell, organ, and tissue development. Therefore, the precise regulation of auxin levels is an essential mechanism to fine-tune the activity of this powerful hormone during plant growth and development. Likewise, cytokinins exhibit a wide range of physiological functions, including regulation of shoot and root apical meristems, stimulation of branching, vascular development, chloroplast differentiation, stabilization of the structure and function of the photosynthetic machinery, delay of senescence, stomata opening, and elevation of the sink strength and nutritional signaling. Moreover, gibberellins also regulate many aspects of plant growth and development including seed germination, stem elongation, leaf expansion, and flower and fruit development. The broad implication of gibberellins in plant development is strictly associated with tight regulation of their metabolism by multiple environmental and endogenous factors, ranging from light and temperature to other hormones including feedback control. Understanding the significant roles of these phytohormones in plant biology, the current subject has attracted the attention of scientists from across the globe. This comprehensive volume “Auxins, Cytokinins and Gibberellins Signaling in Plants” highlights the various prospects involved in the current scenario. The book comprises the chapters from diverse areas dealing with biotechnology, molecular biology, proteomics, genomics, metabolomics, etc.

Plant Hormones: Biosynthesis and Mechanisms of Action is based on research funded by the Chinese government’s National Natural Science Foundation of China (NSFC). This book brings a fresh understanding of hormone biology, particularly molecular mechanisms driving plant hormone actions. With growing understanding of hormone biology comes new outlooks on how mankind values and utilizes the built-in potential of plants for improvement of crops in an environmentally friendly and sustainable manner. This book is a comprehensive description of all major plant hormones: how they are synthesized and catabolized; how they are perceived by plant cells; how they trigger signal transduction; how they regulate gene expression; how they regulate plant growth, development and defense responses; and how we measure plant hormones. This is an exciting time for researchers interested in plant hormones. Plants rely on a diverse set of small molecule hormones to regulate every aspect of their biological processes including development, growth, and adaptation. Since the discovery of the first plant hormone auxin, hormones have always been the frontiers of plant biology. Although the physiological functions of most plant hormones have been studied for decades, the last 15 to 20 years have seen a dramatic progress in our understanding of the molecular mechanisms of hormone actions. The publication of the whole genome sequences of the model systems of Arabidopsis and rice, together with the advent of multidisciplinary approaches has opened the door to successful experimentation on plant hormone actions. Offers a comprehensive description of all major plant hormones including the recently discovered strigolactones and several peptide hormones Contains a chapter describing how plant hormones regulate stem cells Offers a fresh understanding of hormone biology, particularly molecular mechanisms driving plant hormone actions Discusses the built-in potential of plants for improvement of crops in an environmentally friendly and sustainable manner