Topic
Ploidy
About: Ploidy is a research topic. Over the lifetime, 8828 publications have been published within this topic receiving 258914 citations.
Papers published on a yearly basis
Papers
More filters
Book•
23 Mar 1992
TL;DR: Chromosomes: Deficiencies, Inversions, and Transposable Elements.
Abstract: Genes. Chromosomes: Deficiencies. Duplications. Inversions. Rings. Translocations. Transpositions. External Anatomy (figure). Normal Chromosome Complement. Special Chromosomes: Balancers. Compound Chromosomes. X-Y Combinations. Y Derivatives. Autosynaptic Chromosomes. Transposable Elements. Departures from Diploidy. Satellite Sequences. Nonchromosomal Inheritance. Cytogenetic Map.
3,102 citations
Academy of Sciences of the Czech Republic1, University of Saskatchewan2, Bayer3, Kansas State University4, University of California, Riverside5, Blaise Pascal University6, Kyoto University7, University of Dundee8, Punjab Agricultural University9, Indian Agricultural Research Institute10, University of Delhi11, University of Tsukuba12, Yokohama City University13, National Research Council14, Norwegian University of Life Sciences15, Sainsbury Laboratory16, Leibniz Association17, United States Department of Energy18, James Hutton Institute19, Institut national de la recherche agronomique20, University of Zurich21, Sabancı University22, Murdoch University23
TL;DR: Insight into the genome biology of a polyploid crop provide a springboard for faster gene isolation, rapid genetic marker development, and precise breeding to meet the needs of increasing food demand worldwide.
Abstract: An ordered draft sequence of the 17-gigabase hexaploid bread wheat (Triticum aestivum) genome has been produced by sequencing isolated chromosome arms. We have annotated 124,201 gene loci distributed nearly evenly across the homeologous chromosomes and subgenomes. Comparative gene analysis of wheat subgenomes and extant diploid and tetraploid wheat relatives showed that high sequence similarity and structural conservation are retained, with limited gene loss, after polyploidization. However, across the genomes there was evidence of dynamic gene gain, loss, and duplication since the divergence of the wheat lineages. A high degree of transcriptional autonomy and no global dominance was found for the subgenomes. These insights into the genome biology of a polyploid crop provide a springboard for faster gene isolation, rapid genetic marker development, and precise breeding to meet the needs of increasing food demand worldwide.
1,421 citations
TL;DR: It is established that 15% of angiosperm and 31% of fern speciation events are accompanied by ploidy increase, and frequency estimates are higher by a factor of four than earlier estimates and lead to a standing incidence of polyploid species within genera of 35% (n = 1,506).
Abstract: Since its discovery in 1907, polyploidy has been recognized as an important phenomenon in vascular plants, and several lines of evidence indicate that most, if not all, plant species ultimately have a polyploid ancestry. However, previous estimates of the frequency of polyploid speciation suggest that the formation and establishment of neopolyploid species is rare. By combining information from the botanical community's vast cytogenetic and phylogenetic databases, we establish that 15% of angiosperm and 31% of fern speciation events are accompanied by ploidy increase. These frequency estimates are higher by a factor of four than earlier estimates and lead to a standing incidence of polyploid species within genera of 35% (n = 1,506). Despite this high incidence, we find no direct evidence that polyploid lines, once established, enjoy greater net species diversification. Thus, the widespread occurrence of polyploid taxa appears to result from the substantial contribution of polyploidy to cladogenesis, but not from subsequent increases in diversification rates of polyploid lines.
1,119 citations
TL;DR: Some of the genetic and genomic attributes of polyploids may have both biochemical and ecological benefits that contribute to the success ofpolyploid plants in nature.
Abstract: In 1950, G. Ledyard Stebbins devoted two chapters of his book Variation and Evolution in Plants (Columbia Univ. Press, New York) to polyploidy, one on occurrence and nature and one on distribution and significance. Fifty years later, many of the questions Stebbins posed have not been answered, and many new questions have arisen. In this paper, we review some of the genetic attributes of polyploids that have been suggested to account for the tremendous success of polyploid plants. Based on a limited number of studies, we conclude: (i) Polyploids, both individuals and populations, generally maintain higher levels of heterozygosity than do their diploid progenitors. (ii) Polyploids exhibit less inbreeding depression than do their diploid parents and can therefore tolerate higher levels of selfing; polyploid ferns indeed have higher levels of selfing than do their diploid parents, but polyploid angiosperms do not differ in outcrossing rates from their diploid parents. (iii) Most polyploid species are polyphyletic, having formed recurrently from genetically different diploid parents. This mode of formation incorporates genetic diversity from multiple progenitor populations into the polyploid “species”; thus, genetic diversity in polyploid species is much higher than expected by models of polyploid formation involving a single origin. (iv) Genome rearrangement may be a common attribute of polyploids, based on evidence from genome in situ hybridization (GISH), restriction fragment length polymorphism (RFLP) analysis, and chromosome mapping. (v) Several groups of plants may be ancient polyploids, with large regions of homologous DNA. These duplicated genes and genomes can undergo divergent evolution and evolve new functions. These genetic and genomic attributes of polyploids may have both biochemical and ecological benefits that contribute to the success of polyploids in nature.
970 citations