Characterisation of the wheat genome by renaturation kinetics

Smith, D. B.; Flavell, R. B.

doi:10.1007/bf00283468

Cited by 128 publications

(91 citation statements)

References 29 publications

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“…This contrasts with other C0t 10-2 fractions isolated from hexaploid wheat at 60°C in 012 M PB which had Tm values 10°C lower than native, total wheat DNA (Dover, 1975;Smith and Flavell, 1975;Ranjekar et al, 1976). …”

Section: Resultsmentioning

confidence: 75%

“…Rapidly renaturing fractions of hexaploid wheat DNA have been isolated (Mitra and Bhatia, 1973;Flavell, 1974, 1975;Dover, 1975;Flavell and Smith, 1976;Ranjekar et al, 1976), up to 10 per cent of the genome being recovered as duplexes by hydroxyapatite chromatography after reassociation to C0t values between 8 x l0 and 2 x 10-2 mol sec 1 in 012 M phosphate buffer at 60°C. This DNA had thermal stabilities 8-10°C lower than that of native, total wheat DNA indicating that mismatched hybrids had been isolated (Dover, 1975;Smith and Flavell, 1975;Ranjekar et al, 1976), and Ranjekar et al (1976) found that the buoyant density profile was broad, with a mean density of I 708 gm/cm3 compared with the density of 1 702 gm/cm3 of the total, native wheat DNA. The mismatching in the renatured molecules may be the result of sequence divergence during the evolution of the families of repeated DNAs (Flavell et al, 1977).…”

Section: Introductionmentioning

confidence: 98%

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Chromosomal locations of highly repeated DNA sequences in wheat

Gerlach

Peacock

1980

Heredity

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SUMMARYC0t l0 DNA was isolated from hexaploid wheat Tr-iticum aestivum cv. Chinese Spring by hydroxyapatite chromatography (70°C in 0l2 M phosphate buffer). The higher Tm of the Cot 10-2 DNA compared with total wheat DNA suggested that it was relatively GC rich and contained well matched hybrids.In situ hybridisation using wheat species of different ploidy levels located major sites of the C0t l0-DNA on the B genome chromosomes. More than one particular highly repeated sequence is located in these sites. Other chromosomal locations could be visualised by heating in situ hybridisation reactions before renaturation. This was attributed to the availability for hybridisation both of chromosomal sequences additional to those normally available after acid denaturation of cytological preparations and to single stranded cRNA molecules which were otherwise present as double stranded structures.

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Section: Resultsmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 98%

Chromosomal locations of highly repeated DNA sequences in wheat

Gerlach

Peacock

1980

Heredity

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“…The approach of using homologies to serine/threonine kinases for cloning candidate resistance genes in the very complex wheat genome (1.6×10 l° bp; Smith and Flavell, 1975) has been successful for the LrlO gene. A similar approach taking advantage of the coding sequence of the new extracellular domain of LRK10 has already identified putative candidates for a number of additional leaf rust resistance genes (Feuillet et al, unpublished data).…”

Section: Discussionmentioning

confidence: 99%

Molecular cloning of a new receptor‐like kinase gene encoded at the Lr10 disease resistance locus of wheat

Feuillet

Schachermayr

Keller³

1997

The Plant Journal

280

154

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SummaryMore than 100 resistance genes against wheat rust pathogens have been described in wheat and its relatives. Although many of them have been extensively used in wheat resistance breeding, none of these resistance loci has yet been analyzed at the molecular level. By screening a set of near-isogenic lines carrying different leaf rust resistance genes with a wheat probe encoding a serine/ threonine protein kinase, we detected a polymorphic DNA fragment in the line with the LrlO resistance gene. This fragment mapped to the LrlO disease resistance locus and encodes a receptor-like protein kinase which we called LRK10. LRK10 contains a new type of extracellular domain not found in known plant or animal receptor kinases. Several conserved amino acids in S-domain glycoproteins and receptor-like kinases were also found in LRK10, suggesting that LRK10 and S-domain proteins belong to the same superfamily of specific recognition molecules in plants. LrklO was expressed at low levels in young seedlings and belongs to a gene family. Analysis of wheat lines with and without the LrlO gene demonstrated that Lrk10 and LrlO belong to the same genetic locus. We conclude that gene isolation based on protein kinase homology can identify new receptor domains and provide candidates for disease resistance genes in the complex wheat genome.

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“…Map-based cloning requires the development of a high resolution map and the possibility to do chromosome walks over large distances up to 1 megabase (Mb). Wheat has a very large genome (1.6 ϫ 10 10 bp for bread wheat), a high content of repetitive sequences (80%) (7), and different wheat species have different levels of ploidy. For example, the hexaploid genome of bread wheat consists of three homeologous genomes (called A, B, and D).…”

mentioning

confidence: 99%

Subgenome chromosome walking in wheat: A 450-kb physical contig in Triticum monococcum L. spans the Lr10 resistance locus in hexaploid wheat ( Triticum aestivum L.)

Stein

Feuillet

Wicker

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

151

117

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For many agronomically important plant genes, only their position on a genetic map is known. In the absence of an efficient transposon tagging system, such genes have to be isolated by mapbased cloning. In bread wheat Triticum aestivum, the genome is hexaploid, has a size of 1.6 ؋ 10 10 bp, and contains more than 80% of repetitive sequences. So far, this genome complexity has not allowed chromosome walking and positional cloning. Here, we demonstrate that chromosome walking using bacterial artificial chromosome (BAC) clones is possible in the diploid wheat Triticum monococcum (A m genome). BAC end sequences were mostly repetitive and could not be used for the first walking step. New probes corresponding to rare low-copy sequences were efficiently identified by low-pass DNA sequencing of the BACs.

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Characterisation of the wheat genome by renaturation kinetics

Cited by 128 publications

References 29 publications

Chromosomal locations of highly repeated DNA sequences in wheat

Chromosomal locations of highly repeated DNA sequences in wheat

Molecular cloning of a new receptor‐like kinase gene encoded at the Lr10 disease resistance locus of wheat

Subgenome chromosome walking in wheat: A 450-kb physical contig in Triticum monococcum L. spans the Lr10 resistance locus in hexaploid wheat ( Triticum aestivum L.)

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