Biomedical subjects

C P Meredith

Publications and source records attributed to C P Meredith.

7 recordsLinked to original sources

PubMed2006

An integrated SSR map of grapevine based on five mapping populations.

A grapevine (mainly Vitis vinifera L., 2n = 38) composite genetic map was constructed with CarthaGene using segregation data from five full-sib populations of 46, 95, 114, 139 and 153 individuals, to determine the relative position of a large set of molecular markers. This consensus map comprised 515 loci (502 SSRs and 13 other type PCR-based markers), amplified using 439 primer pairs (426 SSRs and 13 others) with 50.1% common markers shared by at least two crosses. Out of all loci, 257, 85, 74, 69 and 30 were mapped in 1, 2, 3, 4 and 5 individual mapping populations, respectively. Marker order was generally well conserved between maps of individual populations, with only a few significant differences in the recombination rate of marker pairs between two or more populations. The total length of the integrated map was 1,647 cM Kosambi covering 19 linkage groups, with a mean distance between neighbour loci of 3.3 cM. A framework-integrated map was also built, with marker order supported by a LOD of 2.0. It included 257 loci spanning 1,485 cM Kosambi with a mean inter-locus distance of 6.2 cM over 19 linkage groups. These integrated maps are the most comprehensive SSR-based maps available so far in grapevine and will serve either for choosing markers evenly scattered over the whole genome or for selecting markers that cover particular regions of interest. The framework map is also a useful starting point for the integration of the V. vinifera physical and genetic maps.

Chromosome Mapping↗

PubMed2004

Development of a standard set of microsatellite reference alleles for identification of grape cultivars.

In order to investigate the comparability of microsatellite profiles obtained in different laboratories, ten partners in seven countries analyzed 46 grape cultivars at six loci (VVMD5, VVMD7, VVMD27, VVS2, VrZAG62, and VrZAG79). No effort was made to standardize equipment or protocols. Although some partners obtained very similar results, in other cases different absolute allele sizes and, sometimes, different relative allele sizes were obtained. A strategy for data comparison by means of reference to the alleles detected in well-known cultivars was proposed. For each marker, each allele was designated by a code based on the name of the reference cultivar carrying that allele. Thirty-three cultivars, representing from 13 to 23 alleles per marker, were chosen as references. After the raw data obtained by the different partners were coded, more than 97% of the data were in agreement. Minor discrepancies were attributed to errors, suboptimal amplification and visualization, and misscoring of heterozygous versus homozygous allele pairs. We have shown that coded microsatellite data produced in different laboratories with different protocols and conditions can be compared, and that it is suitable for the identification and SSR allele characterization of cultivars. It is proposed that the six markers employed here, already widely used, be adopted as a minimal standard marker set for future grapevine cultivar analyses, and that additional cultivars be characterized by means of the coded reference alleles presented here. The complete database is available at http://www.genres.de/eccdb/vitis/ Cuttings of the 33 reference cultivars are available on request from the Institut National de la Recherche Agronomique Vassal collection (didier.vares@ensam.inra.fr).

Alleles↗

PubMed2003

A microsatellite marker based framework linkage map of Vitis vinifera L.

We have constructed a framework linkage map based on microsatellite markers for Vitis vinifera L., the European wine grape. The mapping population consisted of 153 progeny plants from a cross of Vitis vinifera cvs. Riesling x Cabernet Sauvignon. One hundred fifty-two microsatellite markers and one polymorphic EST marker have been mapped to 20 linkage groups (2 n=38). The map covers 1,728 cM with an average distance between markers of 11.0 cM. Estimates of genome size, expected genome coverage, and observed genome coverage were determined with 135-140 markers. Genome length estimates differed between paternal and maternal data sets. Observed approximate genome coverage was 65% versus an expected coverage of 90%. Meiotic recombination rates were not significantly different between maternal and paternal parents. This map has been adopted as a reference map for the International Grape Genome Program.

Genetic Linkage↗

PubMed2003

Microsatellite analysis of ancient alpine grape cultivars: pedigree reconstruction of Vitis vinifera L. 'Cornalin du Valais'.

Ancient and closely related grape cultivars from the Alps were analyzed with 50 microsatellite markers: 'Cornalin', 'Humagne Rouge' and 'Goron' from Valais (Switzerland); 'Cornalin', 'Petit Rouge' and 'Mayolet' from the Aosta Valley (Italy). Our results confirmed previous studies showing that the 'Cornalin' cultivars from Switzerland and Italy are distinct, and that 'Humagne Rouge' is identical to 'Cornalin' from the Aosta Valley. We propose the nomenclature 'Cornalin du Valais' and 'Cornalin d'Aoste' in order to prevent further confusion. At each locus, 'Goron', 'Petit Rouge', 'Mayolet' and 'Cornalin d'Aoste' all share at least one allele with 'Cornalin du Valais', strongly suggesting parent/offspring relationships. Alleles at 49 out of 50 microsatellite loci are consistent with 'Cornalin du Valais' being the progeny of 'Petit Rouge' and 'Mayolet'. The exception is a 10-base pair discrepancy at one locus, most likely the result of somatic mutation in one of the parents, since this parentage is supported by high likelihood ratios and historical data. We hypothesize that 'Cornalin du Valais' originated in the Aosta Valley through a natural cross and was then introduced into Valais centuries ago, probably via the Great St. Bernard Pass. Furthermore, 'Cornalin du Valais' is likely to be one of the parents of both 'Goron' and 'Cornalin d'Aoste', the respective second parents remaining unknown. This pedigree provides a convincing explanation for the allele-sharing patterns and is strongly supported by historical data. The present work is the first grapevine parentage study to deal with a multiple repeat unit discrepancy at a microsatellite locus. We suggest that the use of increasingly large numbers of loci in making parentage determinations leads to a corresponding increase in the probability of encountering a locus with intra-cultivar variability during the analysis. We therefore assume that a sole multiple repeat unit discrepancy is not sufficient to discard a parentage hypothesis.

Gene Frequency↗

PubMed2001

Simple sequence repeat analysis of a clonally propagated species: a tool for managing a grape germplasm collection.

The USDA germplasm repositories help to preserve the genetic variability of important crop species by collecting and maintaining representative cultivars and related germplasm. Simple sequence repeat markers with high allelic diversity were used to type 41 grapevines from 40 accessions. All vines were either seedless table grape cultivars or cultivars with names similar to table grape cultivars. The proportion of shared alleles was selected as the most appropriate statistical measure of genetic distance for this population. In conjunction with morphological traits, known synonyms were confirmed and a previously unknown synonym was discovered. An alleged synonym in the literature was disproved by the DNA data. The data were consistent with known parentage, where such data were available. Two mislabeled vines in the USDA collection were identified. UPGMA grouped the cultivars loosely into three groups: a group of nine mostly Middle Eastern cultivars, a group of 22 accessions mostly from Russia and Afghanistan that were morphologically similar to 'Thompson Seedless', and a third very loose group of 11 accessions consisting mostly of eastern European wine grape cultivars. The limitations and usefulness of this type of analysis are discussed.

Alleles↗

PubMed2000

Vitis vinifera must varietal authentication using microsatellite DNA analysis (SSR).

A microsatellite DNA-based method for Vitis vinifera grape must authentication is presented. Five of the most important port wine producing grape cultivars (Tinta Roriz, Tinto Cão, Touriga Francesa, Touriga Nacional, and Tinta Barroca) were typed at four microsatellite loci described by Bowers et al. (Genome 1996, 39, 628-633) and Thomas and Scott (Theor. Appl. Genet. 1993, 86, 985-990). The corresponding 5 varietal musts and 26 must mixtures that result from the combination of the five varieties were also typed at the four loci. There were no differences between the corresponding leaf and varietal must profiles. All must combinations showed the expected band profiles corresponding to the sum of the varietal band profile components. Among the 26 must mixtures, 8 could be discriminated using the four loci.

DNA, Plant↗

PubMed1997

The parentage of a classic wine grape, Cabernet Sauvignon.

The world's great wines are produced from a relatively small number of classic European cultivars of Vitis vinifera L Most are thought to be centuries old and their origins have long been the subject of speculation. Among the most prominent of these cultivars is Cabernet Sauvignon, described as "the world's most renowned grape variety for the production of fine red wine". Although now grown in many countries, Cabernet Sauvignon derives its fame from its long association with the Bordeaux region of France, where it has been grown at least since the 17th century. We present microsatellite DNA evidence for the hypothesis that Cabernet Sauvignon is the progeny of two other Bordeaux cultivars, Cabernet franc and Sauvignon blanc. Likelihood ratios support this hypothesis to a very high degree of probability. A close relationship between Cabernet Sauvignon and Cabernet franc has been suspected but the genetic contribution of Sauvignon blanc, despite its similar name, is a surprise.

Alleles↗