Genome Plasticity a Key Factor in the Success of Polyploid Wheat Under Domestication

Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA.
Science (Impact Factor: 33.61). 07/2007; 316(5833):1862-6. DOI: 10.1126/science.1143986
Source: PubMed


Wheat was domesticated about 10,000 years ago and has since spread worldwide to become one of the major crops. Its adaptability to diverse environments and end uses is surprising given the diversity bottlenecks expected from recent domestication and polyploid speciation events. Wheat compensates for these bottlenecks by capturing part of the genetic diversity of its progenitors and by generating new diversity at a relatively fast pace. Frequent gene deletions and disruptions generated by a fast replacement rate of repetitive sequences are buffered by the polyploid nature of wheat, resulting in subtle dosage effects on which selection can operate.

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Available from: Jan Dvorak, Apr 01, 2014
    • ", 2000 ; Doebley et al . , 2006 ; Bai and [ 4 4 _ T D $ D I F F ] Lindhout , 2007 ; Dubcovsky and Dvorak , 2007 ; Fuller , [ 4 5 _ T D $ D I F F ] 2007 ; Brown et al . , 2008 ; Burger et al . "
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    ABSTRACT: Rapid progress in genomic research and the development of genome-wide molecular markers for various crops significantly improved our knowledge on plant domestication and evolution. Molecular markers and other genomic tools have been used to understand the evolutionary changes that converted wild plants into domesticated crops, and the identification of loci behind domestication syndrome traits will have significant importance in the fast-track domestication of new plants. The application of genomics-assisted selection in plant breeding programs has significantly contributed to efficient plant breeding for desirable traits. Genomic tools also facilitated the efficient identification of progenitors of crops as well as centers of domestication. Multiple genomic regions with signature of selection during plant domestication have been found in various crops. Extensive analyses of plant genomes revealed that genes underlying domestication syndrome traits show a significant loss of diversity, for example, up to 95% of genetic diversity in wild relatives has been lost during domestication process in extreme cases. Genomic research revealed repeated occurrence of polyploidization during plant evolution and various interesting events that occurred following polyploidization such as gene loss and silencing. The loss of most replicated genes through time and nonrandom retention of some duplicated genes that serve as signatures of polyploidy are among interesting changes in polyploid plant genomes. Further insights into the advances in our knowledge on plant domestication and evolution made through the use of DNA markers and genomic tools is provided in this paper.
    No preview · Article · Jan 2016 · Advances in Agronomy
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    • "Bread wheat (Triticum aestivum) is an allohexaploid crop derived from the hybridization of diploid Aegilops tauschii with tetraploid wild emmer, Triticum turgidum ssp. dicoccoides (Dubcovsky and Dvorak, 2007; Matsuoka, 2011; Shewry, 2009). This hybridization , subsequent domestication and inbreeding have reduced genetic diversity in cultivated wheat compared with its wild ancestors (Haudry et al., 2007; Tanksley and McCouch, 1997). "
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    ABSTRACT: In wheat, a lack of genetic diversity between breeding lines has been recognized as a significant block to future yield increases. Species belonging to bread wheat's secondary and tertiary gene pools harbour a much greater level of genetic variability, and are an important source of genes to broaden its genetic base. Introgression of novel genes from progenitors and related species has been widely employed to improve the agronomic characteristics of hexaploid wheat, but this approach has been hampered by a lack of markers that can be used to track introduced chromosome segments. Here, we describe the identification of a large number of single nucleotide polymorphisms that can be used to genotype hexaploid wheat and to identify and track introgressions from a variety of sources. We have validated these markers using an ultra-high-density Axiom® genotyping array to characterize a range of diploid, tetraploid and hexaploid wheat accessions and wheat relatives. To facilitate the use of these, both the markers and the associated sequence and genotype information have been made available through an interactive web site.
    Full-text · Article · Oct 2015 · Plant Biotechnology Journal
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    • "WGD has been implicated in speciation and biodiversification, providing new genetic combinations in natural populations to favour evolution and increasing organism complexity (Soltis et al., 2014). In addition , polyploidy has played an essential role in the domestication of many crops, such as maize, wheat, and cotton (Dubcovsky and Dvorak, 2007). Recent and ancient polyploidization events occurred in plants with a high frequency, particularly in angiosperms. "
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    ABSTRACT: Polyploidy is a common event in plants that involves the acquisition of more than two complete sets of chromosomes. Allopolyploidy originates from interspecies hybrids while autopolyploidy originates from intraspecies whole genome duplication (WGD) events. In spite of inconveniences derived from chromosomic rearrangement during polyploidization, natural plant polyploids species often exhibit improved growth vigour and adaptation to adverse environments, conferring evolutionary advantages. These advantages have also been incorporated into crop breeding programmes. Many tetraploid crops show increased stress tolerance, although the molecular mechanisms underlying these different adaptation abilities are poorly known. Understanding the physiological, cellular, and molecular mechanisms coupled to WGD, in both allo- and autopolyploidy, is a major challenge. Over the last few years, several studies, many of them in Arabidopsis, are shedding light on the basis of genetic, genomic, and epigenomic changes linked to WGD. In this review we summarize and discuss the latest advances made in Arabidopsis polyploidy, but also in other agronomic plant species.
    Full-text · Article · Sep 2015 · Journal of Experimental Botany
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