World population is increasing at an alarming rate and this has resulted in increasing tremendously the demand for tree products such as wood for construction materials, fuel and paper, fruits, oils and medicines etc. This has put immense pressure on the world’s supplies of trees and raw material to industry and will continue to do so as long as human population continues to grow. Also, the quality of human diet, especially nutritional components, is adversely affected due to limited genetic improvement of most of fruit trees. Thus there is an immediate need to increase productivity of trees. Improvement has been made through conventional breeding methods, however, conventional breeding is very slow due to long life cycle of trees. A basic strategy in tree improvement is to capture genetic gain through clonal propagation. Clonal propagation via organogenesis is being used for the production of selected elite individual trees. However, the methods are labour intensive, costly, and produce low volumes. Genetic gain can now be captured through somatic embryogenesis. Formation of embryos from somatic cells by a process resembling zygotic embryogenesis is one of the most important features of plants. In 1958, Reinert in Germany and Steward in USA independently reported somatic embryogenesis in carrot cultures. Since then, tremendous progress in somatic embryogenesis of woody and non-woody plants has taken place. It offers a potentially large-scale propagation system for superior clones.

The quality of human life has been maintained and enhanced for generations by the use of trees and their products. In recent years, ever rising human population growth has put tremendous pressure on trees and tree products; growing awareness of the potential of previously unexploited tree resources and environmental pollution have both accelerated development of new technologies for tree propagation, breeding and improvement. Biotechnology of trees may be the answer to solve the problems which cannot be solved by conventional breeding methods. The combination of biotechnology and conventional methods such as plant propagation and breeding may be a novel approach to improving and multiplying in large number the trees and woody plants. So far, plant tissue culture technology has largely been exploited in the propagation of ornamental plants, especially foliage house plants, by com mercial companies. Generally, tissue culture of woody plants has been recal citrant. However, limited success has been achieved in tissue culture of angiosperm and gymnosperm woody plants. A number of recent reports on somatic embryogenesis in woody plants such as Norway spruce (Picea abies), Loblolly pine (Pinus taeda), Sandalwood (Santalurn album), Citrus, Mango (Mangifera indica), etc. , offer a ray of hope of: a) inexpensive clonal propa gation for large-scale production of plants or "emblings" or "somatic embryo plants", b) protoplast work, c) cryopreservation, d) genetic transformation, and e) artificial or manufactured seed production.

World population is increasing at an alarming rate and this has resulted in increasing tremendously the demand for tree products such as wood for construction materials, fuel and paper, fruits, oils and medicines etc. This has put immense pressure on the world’s supplies of trees and raw material to industry and will continue to do so as long as human population continues to grow. Also, the quality of human diet, especially nutritional components, is adversely affected due to limited genetic improvement of most of fruit trees. Thus there is an immediate need to increase productivity of trees. Improvement has been made through conventional breeding methods, however, conventional breeding is very slow due to long life cycle of trees. A basic strategy in tree improvement is to capture genetic gain through clonal propagation. Clonal propagation via organogenesis is being used for the production of selected elite individual trees. However, the methods are labour intensive, costly, and produce low volumes. Genetic gain can now be captured through somatic embryogenesis. Formation of embryos from somatic cells by a process resembling zygotic embryogenesis is one of the most important features of plants. In 1958, Reinert in Germany and Steward in USA independently reported somatic embryogenesis in carrot cultures. Since then, tremendous progress in somatic embryogenesis of woody and non-woody plants has taken place. It offers a potentially large-scale propagation system for superior clones.

The rapid progress made on somatic embryogenesis and its prospects for potential applications in improving woody plants prompted us to edit this book initially in three volumes, and now to add two more volumes. The editors were all convinced that such a treatise was needed and would be extremely useful to researchers and students. This Volume 4 has been divided into three sections and contains 23 chapters. Section A contains eleven chapters covering studies of embryo development and cell biology of white spruce, proliferative somatic embryogenesis in woody species, somatic embryo germination and desiccation tolerance in conifers, performance of conifer somatic seedlings, apoptosis during early somatic embryogenesis, water relation parameters in conifer embryos, image analysis of somatic embryos, somatic embryogenesis in woody legumes, cold storage and cryopreservation, and commercialization of plant somatic embryogenesis. Section B contains six chapters dealing with angiosperm woody plants, such as somatic embryogenesis in myrtaceous plants, Laurus nobilis, Simarouba glauca, Magnolia spp., Juglans cinera, and somatic embryogenesis and evaluation of variability in somatic seedlings of Quercus serrata by RAPD markers. The chapters contained in Section C are focused on somatic embryogenesis in gymnosperms, including Pinus patula, Encephalartos, Picea wilsonii, Pinus banksiana, hybrid firs, and Taxus. All the chapters have been peer-reviewed and revised accordingly to improve their quality.

High-efficiency micropropagation, with relatively low labour costs, has been demonstrated in this unique book detailing liquid media systems for plant tissue culture. World authorities (e.g. von Arnold, Curtis, Takayama, Ziv) contribute seminal papers together with papers from researchers across Europe that are members of the EU COST Action 843 "Advanced micropropagation systems". First-hand practical applications are detailed for crops – including ornamentals and trees – using a wide range of techniques, from thin-film temporary immersion systems to more traditional aerated bioreactors with many types of explant – shoots to somatic embryos. The accounts are realistic, balanced and provide a contemporary account of this important aspect of mass propagation. This book is essential reading for all those in commercial micropropagation labs, as well as researchers worldwide who are keen to improve propagation techniques and lower economic costs of production. Undergraduate and postgraduate students in the applied plant sciences and horticulture will find the book an enlightened treatise.

It is a pleasure to contribute the foreword to Introduction to Cell and Tissue Culture: The ory and Techniques by Mather and Roberts. Despite the occasional appearance of thought ful works devoted to elementary or advanced cell culture methodology, a place remains for a comprehensive and definitive volume that can be used to advantage by both the novice and the expert in the field. In this book, Mather and Roberts present the relevant method ology within a conceptual framework of cell biology, genetics, nutrition, endocrinology, and physiology that renders technical cell culture information in a comprehensive, logical for mat. This allows topics to be presented with an emphasis on troubleshooting problems from a basis of understanding the underlying theory. The material is presented in a way that is adaptable to student use in formal courses; it also should be functional when used on a daily basis by professional cell culturists in a- demia and industry. The volume includes references to relevant Internet sites and other use ful sources of information. In addition to the fundamentals, attention is also given to mod ern applications and approaches to cell culture derivation, medium formulation, culture scale-up, and biotechnology, presented by scientists who are pioneers in these areas. With this volume, it should be possible to establish and maintain a cell culture laboratory devot ed to any of the many disciplines to which cell culture methodology is applicable.