Genetic variability is an important parameter for plant breeders in any con ventional crop improvement programme. Very often the desired variation is un available in the right combination, or simply does not exist at all. However, plant breeders have successfully recombined the desired genes from cultivated crop gerrnplasm and related wild species by sexual hybridization, and have been able to develop new cultivars with desirable agronomie traits, such as high yield, disease, pest, and drought resistance. So far, conventional breeding methods have managed to feed the world's ever-growing population. Continued population growth, no further scope of expanding arable land, soil degradation, environ mental pollution and global warrning are causes of concern to plant biologists and planners. Plant breeders are under continuous pressure to improve and develop new cultivars for sustainable food production. However, it takes several years to develop a new cultivar. Therefore, they have to look for new technologies, which could be combined with conventional methods to create more genetic variability, and reduce the time in developing new cultivars, with early-maturity, and improved yield. The first report on induced mutation of a gene by HJ. Muller in 1927 was a major mi1estone in enhancing variation, and also indicated the potential applica tions of mutagenesis in plant improvement. Radiation sources, such as X-rays, gamma rays and fast neutrons, and chemical mutagens (e. g., ethyl methane sulphonate) have been widely used to induce mutations."

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 a tremendous pressure on trees and tree products; growing awareness of the potential of previously unexploited tree resources; and environmental pollution have both accelerated the development of new technologies for tree propagation, breeding and improvement. Biotechnology of trees may be the answer to solve the problems which can not be solved by conventional breeding methods. The combination of biotechnology and conventional methods such as plant propagation and breeding could become a novel approach to improving and multiplying a large number of the trees and woody plants. So far, plant tissue culture technology has largely been exploited by commercial companies in propagation of ornamentals, especially foliage house plants. Generally, tissue culture of woody plants has been recalcitrant. 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 (Santalum album), Citrus and mango (Mangifera indica), offer a ray of hope for inexpensive clonal propagation for large-scale production of plants or 'emblings' or somatic seedlings; protoplast work; cryopreservation; genetic transformation; and synthetic or artificial or manufactured seed production.

This book volume has been divided into three sections and contains a total of 23 chapters. Section A contains eleven chapters covering topics such as 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 crypreservation, and commercialization of plant somatic embryogenesis. Section B comprisis 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 focussed on somatic embryogenesis in gymnosperms, including Pinus patula, Encephalartos, Picea wilsonii, Pinus banksiana, hybrid firs, and Taxus. All the mansucripts have been peer reviewed and revised accordingly to improve the quality of these chapters. The final manuscripts were submitted as camera- ready to publication, and editors had no opportunity to go through them again before the final printing. Authors were advised to prepare final camera-ready manuscripts carefully to avoid any mistakes. Therefore, editors are not respon- sible for mistakes, if any, in this book volume. We are grateful to all the book chapter contributors for submitting their manuscripts in time, and to the reviewers for giving their free time to review the manuscripts.

The rapid progress on somatic embryogenesis and its prospects for potential application to improving woody plants prompted us to edit this book initially in three volumes, and now an additional three more volumes. We were all convinced that such a treatise was needed and would be extremely useful to researchers and students. This volume 6 is dedicated to Prof. Harry Waris, Helsinki, Finland, who did pioneer work on somatic embryogenesis during the time when Prof. Steward and others were actively engaged in this area. His former student Prof. Liisa Simols, University of Helsinki, Finland, has written a dedication Harry Waris, a pioneer in somatic embryogenesis' to her teacher Prof. Waris. This volume is divided into three sections and contains a total of 26 chapters. Section A comprises seven chapters covering topics such as: Historical insights into some contemporary problems in somatic embryogenesis (SE); Thin cell layer for somatic embryogenesis induction in woody trees; SE in tropical fruit and forest trees; SE in fruit and forest arid trees; Status of SE in Indian forest trees; SE research in fruit trees in India; Applications of SE for the improvement of tropical fruit trees. Section B comprises 15 chapters, dealing with: SE in oil palm, hazelnut (Corylus avellana L.), pistachio (Pistacia vera L.), Araucaria angustifolia, Quercus suber, Aspidosperma polyneuron, Acacia senegal, Simmondsia chiensis, Cupressus sempervirens, pecan (Carya illinoinensis), rattan (Calamus spp.), tamarillo (Cyphomandra betacea, longan (Dimocarpus longan Lor.), Aegle marmelos, and Euonymus europaeus. Section C comprises three chapters related to cryo-storage of citrus, conifers and rubber. All the chaptershave been peer-reviewed and revised accordingly to improve the quality of the chapters. We are thankful to all: (a) contributory authors for their co-operation in submitting manuscripts in time, and (b) reviewers for spending their valuable time in reviewing the manuscripts.

Woody plants belong to various taxonomic groups, which are heterogeneous in morphology, physiology, and geographic distribution. OtheJWise, they have neither strong evolutionruy relationships nor share a conunon habitat. They are a primaIy source of fiber and timber, and also include many edible fruit species. Their unique phenotypic behavior includes a perennial habit associated with extensive secondary growth. Additional characteristics of woody plants include: developmental juvenility and maturity with respect to growth habit, flowering time, and morphogenetic response in tissue cultures; environmental control of bud dormancy and flowering cycles; variable tolerance to abiotic stresses, wounding and pathogens; and long distance transport of water and IRltrients. Woody plants, particularly tree species, have been the focus of numerous physiological studies to understand their specialized functions, however, only recently they have become the target of molecular studies. Recent advances in our understanding of signal transduction pathways for environmental responses in herbaceous plants, including the identification and cloning of genes for proteins involved in signal transduction. should provide useful leads to undertake parallel studies with woody plants. Molecular mapping techniques, coupled with the availability of cloned genes from herbaceous plants, should provide shortcuts to cloning relevant genes from woody plants. The unique phenotypes of these plants can then be targeted for improvement through genetic engineering.

This two-volume book gives a broad coverage of various aspects of plant molecular biology relevant to the improvement of woody plants. The authors provide background information on genetic engineering and molecular marker techniques, and specific examples of species in which sufficient progress has been made.

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 a tremendous pressure on trees and tree products; growing awareness of the potential of previously unexploited tree resources; and environmental pollution have both accelerated the development of new technologies for tree propagation, breeding and improvement. Biotechnology of trees may be the answer to solve the problems which can not be solved by conventional breeding methods. The combination of biotechnology and conventional methods such as plant propagation and breeding could become a novel approach to improving and multiplying a large number of the trees and woody plants. So far, plant tissue culture technology has largely been exploited by commercial companies in propagation of ornamentals, especially foliage house plants. Generally, tissue culture of woody plants has been recalcitrant. 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 (Santalum album), Citrus and mango (Mangifera indica), offer a ray of hope for inexpensive clonal propagation for large-scale production of plants or 'emblings' or somatic seedlings; protoplast work; cryopreservation; genetic transformation; and synthetic or artificial or manufactured seed production.

This two-volume book gives a broad coverage of various aspects of plant molecular biology relevant to the improvement of woody plants. The authors provide background information on genetic engineering and molecular marker techniques, and specific examples of species in which sufficient progress has been made.

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 a tremendous pressure on trees and tree products; growing awareness of the potential of previously unexploited tree resources; and environ mental pollution have both accelerated the development of new technologies for tree propagation, breeding and improvement. Biotechnology of trees may be the answer to solve the problems which can not 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 a large number of the trees and woody plants. So far, plant tissue culture technology has largely been exploited by commercial companies in propagation of ornamentals, especially foliage house plants. Gene rally, tissue culture of woody plants has been recalcitrant. 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 taedb), Sandalwood (Santalum album), Citrus, mango (Mangifera indica), etc., offer a ray of hope of: a) inexpensive clonal propagation for large-scale production of plants or "emblings" or somatic seedlings; b) protoplast work; c) cryopreservation; d) genetic transformation; and e) synthetic or artificial or manufactured seed production."

Genetic variability is an important parameter for plant breeders in any con ventional crop improvement programme. Very often the desired variation is un available in the right combination, or simply does not exist at all. However, plant breeders have successfully recombined the desired genes from cultivated crop gerrnplasm and related wild species by sexual hybridization, and have been able to develop new cultivars with desirable agronomie traits, such as high yield, disease, pest, and drought resistance. So far, conventional breeding methods have managed to feed the world's ever-growing population. Continued population growth, no further scope of expanding arable land, soil degradation, environ mental pollution and global warrning are causes of concern to plant biologists and planners. Plant breeders are under continuous pressure to improve and develop new cultivars for sustainable food production. However, it takes several years to develop a new cultivar. Therefore, they have to look for new technologies, which could be combined with conventional methods to create more genetic variability, and reduce the time in developing new cultivars, with early-maturity, and improved yield. The first report on induced mutation of a gene by HJ. Muller in 1927 was a major mi1estone in enhancing variation, and also indicated the potential applica tions of mutagenesis in plant improvement. Radiation sources, such as X-rays, gamma rays and fast neutrons, and chemical mutagens (e. g., ethyl methane sulphonate) have been widely used to induce mutations."

Woody plants belong to various taxonomic groups, which are heterogeneous in morphology, physiology, and geographic distribution. OtheJWise, they have neither strong evolutionruy relationships nor share a conunon habitat. They are a primaIy source of fiber and timber, and also include many edible fruit species. Their unique phenotypic behavior includes a perennial habit associated with extensive secondary growth. Additional characteristics of woody plants include: developmental juvenility and maturity with respect to growth habit, flowering time, and morphogenetic response in tissue cultures; environmental control of bud dormancy and flowering cycles; variable tolerance to abiotic stresses, wounding and pathogens; and long distance transport of water and IRltrients. Woody plants, particularly tree species, have been the focus of numerous physiological studies to understand their specialized functions, however, only recently they have become the target of molecular studies. Recent advances in our understanding of signal transduction pathways for environmental responses in herbaceous plants, including the identification and cloning of genes for proteins involved in signal transduction. should provide useful leads to undertake parallel studies with woody plants. Molecular mapping techniques, coupled with the availability of cloned genes from herbaceous plants, should provide shortcuts to cloning relevant genes from woody plants. The unique phenotypes of these plants can then be targeted for improvement through genetic engineering.

This book volume has been divided into three sections and contains a total of 23 chapters. Section A contains eleven chapters covering topics such as 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 crypreservation, and commercialization of plant somatic embryogenesis. Section B comprisis 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 focussed on somatic embryogenesis in gymnosperms, including Pinus patula, Encephalartos, Picea wilsonii, Pinus banksiana, hybrid firs, and Taxus. All the mansucripts have been peer reviewed and revised accordingly to improve the quality of these chapters. The final manuscripts were submitted as camera- ready to publication, and editors had no opportunity to go through them again before the final printing. Authors were advised to prepare final camera-ready manuscripts carefully to avoid any mistakes. Therefore, editors are not respon- sible for mistakes, if any, in this book volume. We are grateful to all the book chapter contributors for submitting their manuscripts in time, and to the reviewers for giving their free time to review the manuscripts.