Wheat

Varshney, Rajeev K.; Balyan, H. S.; Langridge, Peter

doi:10.1007/978-3-540-34389-9_2

Cited by 9 publications

(6 citation statements)

References 470 publications

(234 reference statements)

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“…SSR markers, on the other hand, have been used extensively in wheat for the construction of genetic maps and the identification of marker-trait associations [69], http://wheat.pw.usda.gov. Therefore, SSRs can serve as excellent anchor points for mapping anonymous markers and as a linking bridge between the available genetic information and the high density RH maps.…”

Section: Discussionmentioning

confidence: 99%

“…The 2D-RH map also provided 5.2 fold higher resolution ( cM/cR ratio of 1:5.2) than the genetic map [38], confirming that RH mapping indeed provides higher resolution than genetic mapping. At the same time, the availability of hundreds of genetic maps and genetically mapped loci in wheat [69] is an asset and this information may provide better consensus maps. In addition, the genetic maps could easily be used for identifying QTL/genes for any phenotypic trait segregating in that population.…”

Section: Discussionmentioning

confidence: 99%

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Physical mapping resources for large plant genomes: radiation hybrids for wheat D-genome progenitor Aegilops tauschii

et al. 2012

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BackgroundDevelopment of a high quality reference sequence is a daunting task in crops like wheat with large (~17Gb), highly repetitive (>80%) and polyploid genome. To achieve complete sequence assembly of such genomes, development of a high quality physical map is a necessary first step. However, due to the lack of recombination in certain regions of the chromosomes, genetic mapping, which uses recombination frequency to map marker loci, alone is not sufficient to develop high quality marker scaffolds for a sequence ready physical map. Radiation hybrid (RH) mapping, which uses radiation induced chromosomal breaks, has proven to be a successful approach for developing marker scaffolds for sequence assembly in animal systems. Here, the development and characterization of a RH panel for the mapping of D-genome of wheat progenitor Aegilops tauschii is reported.ResultsRadiation dosages of 350 and 450 Gy were optimized for seed irradiation of a synthetic hexaploid (AABBDD) wheat with the D-genome of Ae. tauschii accession AL8/78. The surviving plants after irradiation were crossed to durum wheat (AABB), to produce pentaploid RH1s (AABBD), which allows the simultaneous mapping of the whole D-genome. A panel of 1,510 RH1 plants was obtained, of which 592 plants were generated from the mature RH1 seeds, and 918 plants were rescued through embryo culture due to poor germination (<3%) of mature RH1 seeds. This panel showed a homogenous marker loss (2.1%) after screening with SSR markers uniformly covering all the D-genome chromosomes. Different marker systems mostly detected different lines with deletions. Using markers covering known distances, the mapping resolution of this RH panel was estimated to be <140kb. Analysis of only 16 RH lines carrying deletions on chromosome 2D resulted in a physical map with cM/cR ratio of 1:5.2 and 15 distinct bins. Additionally, with this small set of lines, almost all the tested ESTs could be mapped. A set of 399 most informative RH lines with an average deletion frequency of ~10% were identified for developing high density marker scaffolds of the D-genome.ConclusionsThe RH panel reported here is the first developed for any wild ancestor of a major cultivated plant species. The results provided insight into various aspects of RH mapping in plants, including the genetically effective cell number for wheat (for the first time) and the potential implementation of this technique in other plant species. This RH panel will be an invaluable resource for mapping gene based markers, developing a complete marker scaffold for the whole genome sequence assembly, fine mapping of markers and functional characterization of genes and gene networks present on the D-genome.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Physical mapping resources for large plant genomes: radiation hybrids for wheat D-genome progenitor Aegilops tauschii

et al. 2012

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“…Genes discussed in this study are underlined. (Varshney et al, 2006). Furthermore, it was previously hypothesized that the barley b-diketone biosynthesis gene(s) might represent a metabolic gene cluster located on the barley 2HS chromosome (Cer-c, Cer-q, and Cer-u;von Wettstein-Knowles, 1992).…”

Section: A B-diketone Metabolic Gene Cluster Is Also Present On the 2mentioning

confidence: 99%

“…Previous genetic work in barley demonstrated that the b-diketone biosynthesisassociated Cer-cqu locus resides in a subtelomeric region on the short arm of chromosome 2H (2HS) (Takahashi et al, 1953;Tsuchiya, 1972;Schondelmaier et al, 1993), in a syntenic position to the wheat W1 locus (Tsunewaki and Ebana, 1999;Varshney et al, 2006). Extensive genetic and biochemical studies in barley proposed a putative b-diketone biosynthesis pathway, which includes three enzymatic steps (von Wettstein-Knowles, 1995, 2012.…”

Section: Introductionmentioning

confidence: 99%

A Metabolic Gene Cluster in the Wheat W1 and the Barley Cer-cqu Loci Determines β-Diketone Biosynthesis and Glaucousness

et al. 2016

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The glaucous appearance of wheat (Triticum aestivum) and barley (Hordeum vulgare) plants, that is the light bluish-gray look of flag leaf, stem, and spike surfaces, results from deposition of cuticular b-diketone wax on their surfaces; this phenotype is associated with high yield, especially under drought conditions. Despite extensive genetic and biochemical characterization, the molecular genetic basis underlying the biosynthesis of b-diketones remains unclear. Here, we discovered that the wheat W1 locus contains a metabolic gene cluster mediating b-diketone biosynthesis. The cluster comprises genes encoding proteins of several families including type-III polyketide synthases, hydrolases, and cytochrome P450s related to known fatty acid hydroxylases. The cluster region was identified in both genetic and physical maps of glaucous and glossy tetraploid wheat, demonstrating entirely different haplotypes in these accessions. Complementary evidence obtained through gene silencing in planta and heterologous expression in bacteria supports a model for a b-diketone biosynthesis pathway involving members of these three protein families. Mutations in homologous genes were identified in the barley eceriferum mutants defective in b-diketone biosynthesis, demonstrating a gene cluster also in the b-diketone biosynthesis Cer-cqu locus in barley. Hence, our findings open new opportunities to breed major cereal crops for surface features that impact yield and stress response.

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“…The advances in functional genomics in delivering bacterial artificial chromosomes (BACs), ESTs, partial gene sequences, full-length cDNA clones, genes and markers have enabled the establishment of molecular maps based on genic markers. The creation of suitable mapping populations and the development of molecular markers have enabled linkage studies in wheat and many QTLs have been identified for yield under drought environments (Varshney et al, 2006). Linkage studies have shown that QTLs for grain yield reside in several chromosomal regions, and measurements of yield components allow us to dissect complex traits to smaller genetic components more amenable for building our knowledge of trait architecture which will inform our future strategies for exploitation.…”

Section: Qtl Discoverymentioning

confidence: 99%

Genomic approaches for designing durum wheat ready for climate change with a focus on drought

Habash

Kehel

Nachit

2009

Journal of Experimental Botany

114

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Climate change is projected to have a significant impact on temperature and precipitation profiles in the Mediterranean basin. The incidence and severity of drought will become commonplace and this will reduce the productivity of rain-fed crops such as durum wheat. Genetic diversity is the material basis for crop improvement and plant breeding has exploited naturally occurring variation to deliver cultivars with improved resistance to abiotic stresses. The coupling of new genomic tools, technologies, and resources with genetic approaches is essential to underpin wheat breeding through marker-assisted selection and hence mitigate climate change. Improvements in crop performance under abiotic stresses have primarily targeted yield-related traits and it is anticipated that the application of genomic technologies will introduce new target traits for consideration in wheat breeding for resistance to drought. Many traits relating to the plant's response and adaptation to drought are complex and multigenic, and quantitative genetics coupled with genomic technologies have the potential to dissect complex genetic traits and to identify regulatory loci, genes and networks. Full realization of our abilities to manipulate metabolism, transduction pathways, and transcription factors for crop improvement ultimately relies on our basic understanding of the regulation of plant networks at all levels of function.

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Wheat

Cited by 9 publications

References 470 publications

Physical mapping resources for large plant genomes: radiation hybrids for wheat D-genome progenitor Aegilops tauschii

Physical mapping resources for large plant genomes: radiation hybrids for wheat D-genome progenitor Aegilops tauschii

A Metabolic Gene Cluster in the Wheat W1 and the Barley Cer-cqu Loci Determines β-Diketone Biosynthesis and Glaucousness

Genomic approaches for designing durum wheat ready for climate change with a focus on drought

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