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DNA

Internationally common abbreviation for the English term deoxyribonucleinacid. The German DNS (deoxyribonucleic acid) is hardly used any more to avoid confusion with the Domain Name System (DNS) of the Internet. The structure of DNA was elucidated in 1953 by James Watson (* 1928) and Francis Crick (1916-2004), who in 1962 received the Nobel Prize for Medicine with Maurice Wilkins (1916-2004). DNA is a polymeric chain molecule in the cell nuclei of all plant, animal and human organisms, which serves as the carrier of information for the maintenance of all life processes and is inherited.

It basically consists of the five elements carbon, hydrogen, oxygen. phosphorus and nitrogen, The basic building blocks of the polymer, the deoxyribonucleotides, are themselves composed of three basic building blocks (deoxyribose, heterocyclic nucleobase, phosphoric acid) and differ essentially in the nature of the bases. Together, they form a long chain molecule composed of two opposing DNA strands in the form of a twisted rope ladder twisted. These are called in condensed (condensed) form as chromosomes (color bodies).

DNA - DNA strands

Genome (adenine, guanine, cytosine, thymine)

By genome or German genome is meant the entirety of the nucleic acid chains in the cell nuclei of the organism. It contains all the information necessary for the development of an organism from an egg cell and is passed on in the germ line from generation to generation. This information is encrypted on the DNA strand in the form of the genetic code, which essentially on four "letters" (the nucleobases A denin, G uanin, C and T ytosin hymin) is based. The DNA in the human genome is subdivided into 23 chromosomes (n = 23), which occur in duplicate (homologous chromosome pairs) (2n = 46). Each one of the two homologous chromosomes comes from the mother or the father. When passed on to the next generation, the mother gives only one of her two chromosomes to the child. Together with the father's simple set of chromosomes, a new diploid chromosome mixture is created. In addition, individual chromosome sections can be exchanged during the process of inheritance (the so-called crossing over), so that each individual has an individual genome pattern, in which the mutation lines of mother and father are each half recombined.

heterozygosity

This phenomenon of a pronounced heterozygosity (Also mixed, gap, unevenness) is the reason for the individual appearance of each individual, and is equally for varieties typical. By spontaneous mutations There are small changes in the genetic information that are passed on to the offspring and lead to the splitting of features into many variants (alleles). Also cloned vines that made vegetative propagation derive from mutations in the genetic material, which develop particularly in very old and heavily propagated grape varieties such as Burgundy and Traminer often occurred. All varieties of the vine subgenus Vitis have a diploid (double) chromosome set with 2x19 chromosomes (n = 19, 2n = 38). These are all Asians Vines (Vitis amurensis etc.), Europeans Vines (Vitis vinifera) and most American vines (Vitis riparia, Vitis rupestris, Vitis labrusca etc.). Due to the same number of chromosomes and non-existent crossing barriers, these can be found in the breeding largely cross new grape varieties easily with each other. The crossbred products between different species are considered as hybrids designated.

American / European hybrids

Identification of grape varieties

But there are also vines species such as the American Vitis rotundifolia with different numbers of chromosomes (n = 20, 2n = 40). Crossing these with species of the subgenus Vitis, no or only sterile offspring arise (2n = 39). For identification or comparison between grape varieties one uses the genetic information at certain gene locations (microsatellites) within the DNA chain. Six to eight microsatellites are usually sufficient for the identification of grape varieties. However, in order to be able to reliably prove descent or family relationships, you need about 25 loci. In the molecular Genetics Such sections are called fingerprints. In the breeding Resistant grape varieties have been used for some time, the not undisputed manipulative genetic engineering (Genetic engineering). Here, foreign genes with desired properties are introduced into the genome of plant cells of certain conventional varieties. For the detection of wine spoilage and for the definition of the percentage of different grape varieties in a wine was in 2002 by the Institute INRA the procedure Nuclear Magnetic Resonance developed.

Grapevine genome

In August 2007, the deciphering of the grapevine genome was announced by Italian and French researchers. It is the first fruit-bearing plant whose DNA sequence is known. The scientists discovered some peculiarities. That for the production of resveratrol competent enzyme Stilbene (an aromatic hydrocarbon) is present 43 times in the genome. The gene for the formation of the flavor terpene There are 89 variants. That is also the cause of the many different ones flavorings of the wine. The comparison with other genomes also shows with which plants the grapevine Is related. According to this, the grapevine genome consists of three predecessor genomes and is more closely related to the poplar than to the rice. Knowledge about the genome could also be helpful to pathogens by going through genetic engineering resistance causes. See regarding the identification of the parents of a variety under molecular Genetics as well as regarding taxonomy under Vines systematics,

Pictures: Ursula Bruehl, Doris Schneider, Julius Kühn Institute (JKI)

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