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molecular Genetics

molecular genetics (GB)

Term for a branch of molecular biology for the study of the structure of the genome (totality of the genetic material in an organism) and the function and the interaction of genes (which in the chromosomes of each cell nucleus on the DNA strand localized genetic factors). Genetic engineering or Genetic Engineering is the application of genetic methods for the practice and means mostly the artificial gene manipulation with the aim of the new contribution of desired, so far nonexistent characteristics such as resistance against fungal diseases into an existing organism by the technically feasible implantation of individual replicated foreign genes from alien organisms into the genome of a variety or breed.

Molecular genetics - DNA strands

Polymerase Chain Reaction

Since the invention of PCR method (Polymerase Chain Reaction) for the duplication of the smallest DNA amounts In the 1990s, grape varieties can now be genotypically clearly characterized, defined and recognized as varieties by molecular genetic characterization methods. This was the genotype in the ampelography introduced as an addition to the traditional, visually on the phenotype based ampelography can help to clarify many unanswered questions. Each stand-alone grape variety sprouted from one seed is represented by a distinctive genotype characterized by the unique recombination of maternal and paternal hereditary traits during fertilization, and is present in the nucleus of each plant cell. Any sexual reproduction vine (like any other sexual reproductive individual too) has an individual genetic pattern that sets it apart from all other grape varieties.

Microsatellite analysis

For genotypic comparisons or the identification of grape varieties as well as the determination of the parent pair, one uses the so-called genetic fingerprint, which can be created with a microsatellite analysis. The microsatellites are defined by molecular markers, retrievable areas within the long DNA chain that have a different number of repeating base sequences. These two-repeating sequences, given the double (2n = 38) set of chromosomes, may be of different lengths between two homologous chromosomes as well as from grape to grape variety. One can copy and duplicate these sequences as single fragments, so that one gets a certain feature by the length of these genomic fragments.

Many such always paired fragments from multiple loci yield a variety-typical fragment pattern indicative of this variety, which can be aligned with the fragment patterns of other grape varieties. This fragment pattern is, so to speak, a genetic fingerprint (fingerprint). The probability that two grape varieties have the same pattern is statistically about 1: 6 million, with only about 14,000 existing grape varieties and breeding strains a vanishingly low probability. Within European vine-growing establishments, it is agreed that genotype characterization of grape varieties is sufficient to determine the genotype at six defined loci (microsatellites) in order to clearly define the profile of a variety.

Prior to the method of microsatellite analysis, variety comparisons and varieties were only comparative morphology (outer shape) of the vine possible. It described the varietal characteristics and tried to filter out characteristics that allowed the varieties to be identified and delineated. These morphological feature catalogs describe the phenotype the grape variety. Both approaches have advantages and disadvantages, but complement each other wonderfully. Genetic analyzes in the laboratory require only a small amount of genetic material as a starting material, the examinations are not dependent on external conditions such as season, plant age, health status, virus status or growth conditions at the site, which can disfigure the phenotype (the exterior) beyond recognition.

color mutations

Laboratory examinations can not simply be carried out blindly on thousands of vines in the field, as is possible quickly and without additional costs with the trained eye of the ampelographer. Also, varieties that look like mutated clones or somatic chimeras vegetative propagation have yet to be better distinguished phenotypically. Because the color mutants of Pinot Noir, namely Pinot Gris and Pinot Blanc, are actually not their own, but different berry color variants of the same grape variety. It is a specific one mutation process which leads to loss of dark color. Somatic chimeras like Pinot Meunier (Black Riesling) or Garnacha Peluda can be much easier and faster visually by the strong leaf hair of the original varieties Pinot Noir or Garnacha Tinta differentiate than through elaborate genetic analyzes.

Pinot Blanc, Pinot Gris, Pinot Noir

For characterization by microsatellite analysis, experience has shown that these six specified markers are sufficient. For the clarification of relationships or even the demarcation of Clone and somatic chimeric Within a variety you have to use significantly more markers. But there is the rare exception that two outwardly different phenotypes (Varieties) have the same genotypic profile on six markers. Something like that can happen when getting out of a grape variety mutations in special cell layers a somatic chimera has branched off. Even with varieties that have originated by self- or backcrossing (mother with child), can still be very similar. Especially in sibling with the same parents, this can sometimes lead to failure in the purely visual identification attempt.

Parentage / parenting

Since the mid-1990s, people have been involved in the genetic characterization of grape varieties. As a basis for comparison purposes, the fingerprints of several thousand varieties of the world's largest grape variety in the Domaine de Vassal were added Montpellier analyzed. A central European grapevine database is being developed (see also VIVC ). In recent years, the pedigree of hundreds of grape varieties has been identified or corrected in many cases compared to the information quite often incorrectly provided by breeders. Major Ampelographers Re DNA analysis are Dr. Jean-Michel Boursiquot Thierry Lacombe (France), Javier Ibáñez (Spain), dr. Erika Maul (Germany), Dr. med. Carole P. Meredith (USA), dr. Ferdinand Regner (Austria), Anna Schneider (Italy) and dr. Joseph. Vouillamoz (Switzerland).

About the DNA analysis The chloroplast can also be the crossing direction be checked (mother and father), because these special organ cells are only used by the mother places passed. In 1997, Meredith and Bowers succeeded in the University of California for the first time to establish the parenting of a grape variety: Cabernet Sauvignon is out Cabernet Franc (Mother) x Sauvignon Blanc (Father) originated. As a result, some important Central European leading varieties as Gouais blanc (White Heunisch), Pinot and Savagnin ( Traminer ) be identified. The high age and the wide distribution of these varieties have promoted the spontaneous Einkreuzung and thus the emergence of many other grape varieties. The Gouais Blanc / Heunisch cultivated in the Middle Ages throughout Central Aegean has crossed in 80 grape varieties alone.

Crossing - Cabernet Franc x Sauvignon Blanc = Cabernet Sauvignon

For the first time, as with the paternity test, the genetic fingerprint can be used to reconstruct ancestry, determine relationships, or cross-breed hybrids recognize. However, a prerequisite is an extensive genetic analysis of at least 15 to 50 gene locations (markers). The Swiss biologist dr. José Vouillamoz thinks it should even be at least 30 to 60 (in the identification of Cabernet Sauvignon it was 35). Only if the potential parents are known by, for example, information from the breeder, are less enough. Since each child inherits one chromosome each from the father and one from the mother, each grape variety at a specific genome must also each have a characteristic with the father places and the other with the mother places have in common. This rule is strict, that is, failure to meet the lineage criterion usually means the end of the lineage hypothesis. The more genomes are included in the study, the safer it is. However, a 100% proof is not achievable because the hypothesis can only ever be positively tested on some selected but never on all loci.

If one of the parents can not be identified because its DNA has not yet been recorded and is not known, or because the species may have already died out, it is possible to prove the relationship between parent plants and offspring of two different varieties. Often sources use the phrase "not directly related". This is usually meant that there is no between the considered grape varieties Parent-offspring relationship that is, there is no "mother-father-child relationship". Direct relationships between grape varieties (ie "mother-father-child") can be clearly reconstructed with the genetic fingerprint. Even with siblings or "distant relatives" such as "aunts" or "uncles" or "cousins", the relationship between the genetic profiles is hardly obvious.

genetic engineering

In the breeding Modern grape varieties with above all determined resistance abilities are used for some time also the manipulative genetic engineering, In this regard, the international project became IGGP (International Grape Genome Program). In tissue culture suspensions, one may introduce foreign resistance genes with desired properties into the genome of plant cells of certain conventional varieties. For example resistance against fungal diseases and virus or against animal pests like the dreaded ones phylloxera, From the genetically manipulated cells, it is possible to regenerate vine plants which, this time, do not represent a new variety, but have essentially preserved the genetic characteristics of the selected variety, but supplemented by the "improving" introduced foreign genes.

However, the hoped-for effects mostly did not materialize or were not satisfactory in practice. In the case of woody plants, it is apparently not enough simply to introduce individual genes into the genome somewhere and to hope that such complex and environmentally-dependent properties as fungal resistance may already be expressed. The extent to which this technology will lead to success and practical application in terms of cost and cost in the vine, is currently not foreseeable and not in demand. In any case, the introduction of genetically manipulated grape clones would further impoverish varieties and further reduce clone diversity to a few Clones to lead. Whether these artificially manipulated and disturbed in their genetic balance vine plants in mass vegetative propagation For a long time to prove stable, you can not answer today seriously.

wine adulteration

DNA analyzes in wine are being used today with great success wine adulteration (Pantschereien) track down. Researchers from the institute INRA In Montpellier, in 2002, a method was developed for DNA isolation from wine and must, with which it is possible to distinguish quality wines from cheaper blends. The methodology has progressed so far that, with unfiltered wine, it is possible to determine from the variety-type fingerprint whether a wine from the grape variety specified has been varietal or added to other grape varieties. A quantitative determination of the proportions of the different varieties in wine is not (yet) possible, but it is very possible to reconstruct which varieties are present in the wine.

So far, the INRA team has identified the genetic profiles of 600 grapevine wines. For bottled wines, the method does not work yet, because in the course of the filtering process, a large part of the DNA (DNA) is filtered out, and the residual concentration of remaining DNA in the finished wine for the genetic analysis is too low. The research, however, continues intensively. By means of the method PNA FISH can be microbiologically based wine faults such as horse sweat be detected. See also the keywords under this topic Nuclear Magnetic Resonance and Certification of vines,

Photos: Ursula Bruehl, Doris Schneider, Julius Kühn Institute (JKI), Federal Research Center for Cultivated Plants,
Institute for Grapevine Breeding Geilweilerhof - 76833 Siebeldingen, GERMANY

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