This book is a printed edition of the Special Issue "Genetics and Genomics of Forest Trees" that was published in Forests

Forest tree improvement has mainly been implemented to enhance the productivity of artificial forests. However, given the drastically changing global environment, improvement of various traits related to environmental adaptability is more essential than ever. This book focuses on genetic information, including trait heritability and the physiological mechanisms thereof, which facilitate tree improvement. Nineteen papers are included, reporting genetic approaches to improving various species, including conifers, broad-leaf trees, and bamboo. All of the papers in this book provide cutting-edge genetic information on tree genetics and suggest research directions for future tree improvement.

Forest tree genetics and genomics are advancing at an accelerated rate, thanks to recent developments in high-throughput, next-generation sequencing capabilities, and novel biostatistical tools. Population and landscape genetics and genomics have seen the rise of new approaches implemented in large-scale studies that employ the use of genome-wide sampling. Such studies have started to discern the dynamics of neutral and adaptive variation in nature and the processes that underlie spatially explicit patterns of genetic and genomic variation in nature. The continuous development of genetic maps in forest trees and the expansion of QTL and association mapping approaches contribute to the unravelling of the genotype-phenotype relationship and lead to marker-assisted and genome-wide selection. However, major challenges lie ahead. Recent literature suggests that species demography and genetic diversity have been affected both by climatic oscillations and anthropogenically induced stresses in a way calls into question the possibility of future adaptation. Moreover, the pace of contemporary environmental change presents a great challenge to forest tree populations and their ability to adapt, taking into consideration their life history characteristics. Several questions emerge that include, but are not limited to, the interpretation of forest tree genome surveillance and their structural/functional properties, the adaptive and neutral processes that have shaped forest tree genomes, the analysis of phenotypic traits relevant to adaptation (especially adaptation under contemporary climate change), the link between epigenetics/epigenomics and phenotype/genotype, and the use of genetics/genomics as well as genetic monitoring to advance conservation priorities.

This Research Topic addresses research in genomics and biotechnology to improve the growth and quality of forest trees for wood, pulp, biorefineries and carbon capture. Forests are the world’s greatest repository of terrestrial biomass and biodiversity. Forests serve critical ecological services, supporting the preservation of fauna and flora, and water resources. Planted forests also offer a renewable source of timber, for pulp and paper production, and the biorefinery. Despite their fundamental role for society, thousands of hectares of forests are lost annually due to deforestation, pests, pathogens and urban development. As a consequence, there is an increasing need to develop trees that are more productive under lower inputs, while understanding how they adapt to the environment and respond to biotic and abiotic stress. Forest genomics and biotechnology, disciplines that study the genetic composition of trees and the methods required to modify them, began over a quarter of a century ago with the development of the first genetic maps and establishment of early methods of genetic transformation. Since then, genomics and biotechnology have impacted all research areas of forestry. Genome analyses of tree populations have uncovered genes involved in adaptation and response to biotic and abiotic stress. Genes that regulate growth and development have been identified, and in many cases their mechanisms of action have been described. Genetic transformation is now widely used to understand the roles of genes and to develop germplasm that is more suitable for commercial tree plantations. However, in contrast to many annual crops that have benefited from centuries of domestication and extensive genomic and biotechnology research, in forestry the field is still in its infancy. Thus, tremendous opportunities remain unexplored. This Research Topic aims to briefly summarize recent findings, to discuss long-term goals and to think ahead about future developments and how this can be applied to improve growth and quality of forest trees.

Forest tree functional genomics; Functional genomics in forest trees; Expressed sequence tag databases from forestry tree species; Proteomics for genetic and physiological studies in forest trees: application in maritime pine; Exploring the transcriptome of the ectomycorrhizal symbiosis; Molecular biology of wood formation; Genomics of wood formation; Molecular genetics of cellulose biosynthesis in trees; Tuning lignin metabolism through genetic engineering in trees; In vitro systems for the study of wood formation; Forest tree transgenesis; Genetic modification in conifer forestry: state of the art and future potential - a case study; Transgenic forest trees for insect resistance; Modification of flowering in forest trees; Stability of transgene expression in Aspen; Asexual production of marker-free transgenetic Aspen using MAT vector systems; Genome mapping in forest trees; High-density linkage maps in conifer species and their potential application; Microsatellites in forest tree species: characteristics, identifcation , and applicatons; Genome mapping in populus; Genetic mapping in Acacias.

This text integrates tree transgenesis, functional genomics, and structural genomics to present a unified approach to research on the molecular biology of forest trees.

This book provides a solid scientific basis for researchers, practitioners and students interested in the application of genetic principles to tropical forest ecology and management. It presents a concise overview of genetic variation, evolutionary processes and the human impact on forest genetic resources in the tropics. In addition, modern tools to assess genetic diversity patterns and the dynamics of genetic structures are introduced to the non-specialist reader.

Wild crop relatives are now playing a significant part in the elucidation and improvement of the genomes of their cultivated counterparts. This work includes comprehensive examinations of the status, origin, distribution, morphology, cytology, genetic diversity and available genetic and genomic resources of numerous wild crop relatives, as well as of their evolution and phylogenetic relationship. Further topics include their role as model plants, genetic erosion and conservation efforts, and their domestication for the purposes of bioenergy, phytomedicines, nutraceuticals and phytoremediation. Wild Crop Relatives: Genomic and Breeding Resources comprises 10 volumes on Cereals, Millets and Grasses, Oilseeds, Legume Crops and Forages, Vegetables, Temperate Fruits, Tropical and Subtropical Fruits, Industrial Crops, Plantation and Ornamental Crops, and Forest Trees. It contains 125 chapters written by nearly 400 well-known authors from about 40 countries.

Tropical climates, which occur between 23°30'N and S latitude (Jacob 1988), encompass a wide variety of plant communities (Hartshorn 1983, 1988), many of which are diverse in their woody floras. Within this geographic region, temperature and the amount and seasonality of rainfall define habitat types (UNESCO 1978). The F AO has estimated that there 1 are about 19 million km of potentially forested area in the global tropics, of which 58% were estimated to still be in closed forest in the mid-1970s (Sommers 1976; UNESCO 1978). Of this potentially forested region, 42% is categorized as dry forest lifezone, 33% is tropical moist forest, and 25% is wet or rain forest (Lugo 1988). The species diversity of these tropical habitats is very high. Raven (1976, in Mooney 1988) estimated that 65% of the 250,000 or more plant species of the earth are found in tropical regions. Of this floristic assemblage, a large fraction are woody species. In the well-collected tropical moist forest of Barro Colorado Island, Panama, 39. 7% (481 of 1212 species) of the native phanerogams are woody, arborescent species (Croat 1978). Another 21. 9% are woody vines and lianas. Southeast Asian Dipterocarp forests may contain 120-200 species of trees per hectare (Whitmore 1984), and recent surveys in upper Amazonia re corded from 89 to 283 woody species ~ 10 cm dbh per hectare (Gentry 1988). Tropical communities thus represent a global woody flora of significant scope.

Marking the change in focus of tree genomics from single species to comparative approaches, this book covers biological, genomic, and evolutionary aspects of angiosperm trees that provide information and perspectives to support researchers broadening the focus of their research. The diversity of angiosperm trees in morphology, anatomy, physiology and biochemistry has been described and cataloged by various scientific disciplines, but the molecular, genetic, and evolutionary mechanisms underlying this diversity have only recently been explored. Excitingly, advances in genomic and sequencing technologies are ushering a new era of research broadly termed comparative genomics, which simultaneously exploits and describes the evolutionary origins and genetic regulation of traits of interest. Within tree genomics, this research is already underway, as the number of complete genome sequences available for angiosperm trees is increasing at an impressive pace and the number of species for which RNAseq data are available is rapidly expanding. Because they are extensively covered by other literature and are rapidly changing, technical and computational approaches—such as the latest sequencing technologies—are not a main focus of this book. Instead, this comprehensive volume provides a valuable, broader view of tree genomics whose relevance will outlive the particulars of current-day technical approaches. The first section of the book discusses background on the evolution and diversification of angiosperm trees, as well as offers description of the salient features and diversity of the unique physiology and wood anatomy of angiosperm trees. The second section explores the two most advanced model angiosperm tree species (poplars and eucalypts) as well as species that are soon to emerge as new models. The third section describes the structural features and evolutionary histories of angiosperm tree genomes, followed by a fourth section focusing on the genomics of traits of biological, ecological, and economic interest. In summary, this book is a timely and well-referenced foundational resource for the forest tree community looking to embrace comparative approaches for the study of angiosperm trees.