Term for a branch of molecular biology for researching the structure of the genome (the entirety of genetic material in an organism) and the function and interaction of genes (the hereditary factors localised on the DNA strand in the chromosomes of each cell nucleus). Genetic engineering or genetic engineering is the application of genetic methods in practice and usually involves the artificial manipulation of genes with the aim of introducing desired, previously non-existent characteristics, such as resistance to fungal diseases, into an existing organism through the technically feasible implantation of individual replicated foreign genes from foreign organisms into the genome of a variety or breed.
Polymerase Chain Reaction
Since the invention of the PCR method (polymerase chain reaction) for the amplification of the smallest amounts of DNA in the 1990s, grape varieties can now also be clearly characterised, defined and recognised genotypically as varieties with the help of molecular genetic characterisation methods. This introduced the genotype into ampelography, which can help to clarify many unanswered questions as a supplement to traditional, visual phenotype-based ampelography. Each independent grape variety germinated from a seed is represented by an unmistakable genotype, which is characterised by the unique new combination of maternal and paternal genetic material during fertilisation and is present in the nucleus of each plant cell. Each grape variety resulting from sexual reproduction has an individual genetic pattern that distinguishes it from all other grape varieties.
Microsatellite analysis
For genotypic comparisons or the identification of grape varieties and the determination of the parent pair, the so-called genetic fingerprint is used, which can be created with a microsatellite analysis. Microsatellites are areas within the long DNA chain that are defined by molecular markers and can be found again, which have a different number of repeating base sequences. In a given double set of chromosomes (2 x 19 = 38), these sequences, which repeat twice, can vary in length between two homologous chromosomes as well as from grape variety to grape variety. These sequences can be copied and duplicated as individual fragments so that a specific characteristic is obtained from the length of these genome fragments.
Genetic fingerprint
Many such fragments from several gene loci, always present in pairs, result in a fragment pattern that is typical of the variety and characterises this variety, which can be compared with the fragment patterns of other grape varieties. This fragment pattern is, so to speak, a genetic fingerprint. The probability of two grape varieties having the same pattern is statistically around 1:6 million, which is a negligible probability given that there are only around 14,000 existing grape varieties and breeding strains. There is an agreement within the European grapevine breeding institutes that it is therefore sufficient for the genotypic characterisation of grapevine varieties to determine the genotype at six defined gene loci (microsatellites) in order to clearly define the profile of a variety.
Visual identification using phenotype
Before the method of microsatellite analysis, it was only possible to compare and differentiate varieties by comparing the morphology (external appearance) of the vine. The characteristics typical of the variety were described and attempts were made to filter out features that allowed...
