Genetics And Genomics Of Polyploid Plants

Polyploidy – whole-genome duplication (WGD) – is a fundamental driver of biodiversity with significant consequences for genome structure, organization, and evolution. Once considered a speciation process common only in plants, polyploidy is now recognized to have played a major role in the structure, gene content, and evolution of most eukaryotic genomes. In fact, the diversity of eukaryotes seems closely tied to multiple WGDs. Polyploidy generates new genomic interactions – initially resulting in “genomic and transcriptomic shock” – that must be resolved in a new polyploid lineage. This process essentially acts as a “reset” button, resulting in genomic changes that may ultimately promote adaptive speciation. This book brings together for the first time the conceptual and theoretical underpinnings of polyploid genome evolution with syntheses of the patterns and processes of genome evolution in diverse polyploid groups. Because polyploidy is most common and best studied in plants, the book emphasizes plant models, but recent studies of vertebrates and fungi are providing fresh perspectives on factors that allow polyploid speciation and shape polyploid genomes. The emerging paradigm is that polyploidy – through alterations in genome structure and gene regulation – generates genetic and phenotypic novelty that manifests itself at the chromosomal, physiological, and organismal levels, with long-term ecological and evolutionary consequences.

Polyploidy plays an important role in biological diversity, trait improvement, and plant species survival. Understanding the evolutionary phenomenon of polyploidy is a key challenge for plant and crop scientists. This book is made up of contributions from leading researchers in the field from around the world, providing a truly global review of the subject. Providing broad-ranging coverage, and up-to-date information from some of the world’s leading researchers, this book is an invaluable resource for geneticists, plant and crop scientists, and evolutionary biologists.

Polyploidy – whole-genome duplication (WGD) – is a fundamental driver of biodiversity with significant consequences for genome structure, organization, and evolution. Once considered a speciation process common only in plants, polyploidy is now recognized to have played a major role in the structure, gene content, and evolution of most eukaryotic genomes. In fact, the diversity of eukaryotes seems closely tied to multiple WGDs. Polyploidy generates new genomic interactions – initially resulting in “genomic and transcriptomic shock” – that must be resolved in a new polyploid lineage. This process essentially acts as a “reset” button, resulting in genomic changes that may ultimately promote adaptive speciation. This book brings together for the first time the conceptual and theoretical underpinnings of polyploid genome evolution with syntheses of the patterns and processes of genome evolution in diverse polyploid groups. Because polyploidy is most common and best studied in plants, the book emphasizes plant models, but recent studies of vertebrates and fungi are providing fresh perspectives on factors that allow polyploid speciation and shape polyploid genomes. The emerging paradigm is that polyploidy – through alterations in genome structure and gene regulation – generates genetic and phenotypic novelty that manifests itself at the chromosomal, physiological, and organismal levels, with long-term ecological and evolutionary consequences.

The Gossypium (cotton) genus presents novel opportunities to advance our understanding of the natural world and its organic evolution. In this book, advances of the past decade are summarized and synthesized to elucidate the current state of knowledge of the structure, function, and evolution of the Gossypium genome, and progress in the application of this knowledge to cotton improvement. This book provides the first comprehensive reference on cotton genomics.

The Genetics and Genomics of the Brassicaceae provides a review of this important family (commonly termed the mustard family, or Cruciferae). The family contains several cultivated species, including radish, rocket, watercress, wasabi and horseradish, in addition to the vegetable and oil crops of the Brassica genus. There are numerous further species with great potential for exploitation in 21st century agriculture, particularly as sources of bioactive chemicals. These opportunities are reviewed, in the context of the Brassicaceae in agriculture. More detailed descriptions are provided of the genetics of the cultivated Brassica crops, including both the species producing most of the brassica vegetable crops (B. rapa and B. oleracea) and the principal species producing oilseed crops (B. napus and B. juncea). The Brassicaceae also include important “model” plant species. Most prominent is Arabidopsis thaliana, the first plant species to have its genome sequenced. Natural genetic variation is reviewed for A. thaliana, as are the genetics of the closely related A. lyrata and of the genus Capsella. Self incompatibility is widespread in the Brassicaceae, and this subject is reviewed. Interest arising from both the commercial value of crop species of the Brassicaceae and the importance of Arabidopsis thaliana as a model species, has led to the development of numerous resources to support research. These are reviewed, including germplasm and genomic library resources, and resources for reverse genetics, metabolomics, bioinformatics and transformation. Molecular studies of the genomes of species of the Brassicaceae revealed extensive genome duplication, indicative of multiple polyploidy events during evolution. In some species, such as Brassica napus, there is evidence of multiple rounds of polyploidy during its relatively recent evolution, thus the Brassicaceae represent an excellent model system for the study of the impacts of polyploidy and the subsequent process of diploidisation, whereby the genome stabilises. Sequence-level characterization of the genomes of Arabidopsis thaliana and Brassica rapa are presented, along with summaries of comparative studies conducted at both linkage map and sequence level, and analysis of the structural and functional evolution of resynthesised polyploids, along with a description of the phylogeny and karyotype evolution of the Brassicaceae. Finally, some perspectives of the editors are presented. These focus upon the Brassicaceae species as models for studying genome evolution following polyploidy, the impact of advances in genome sequencing technology, prospects for future transcriptome analysis and upcoming model systems.

The application of new molecular technology has greatly increased our understanding of the role of chromosomal change in plant evolution. There is now a broad database on genome size variation within and among species and a wide array of nuclear and cytoplasmic genetic markers. There is a variety of literatures addressing this subject but much of it is scattered. This book created a contemporary synthesis or work in this area and addresses issues such as herogeneity, polyploidy, chromosomal rearrangements within species and phenotypic consequences of chromosome doubling.