Mutations (from the Latin mutare "change, transform") are spontaneous changes in the genetic information in the genome of the cell nuclei of plant and animal organisms that occur naturally and play an important role in evolution. These mostly occur selectively (point mutations), but can also be larger DNA segments include (deletion, insertion, chromosome breaks). If the mutations occur in the germline, they are passed on to the next generation. If the organism is not cloned or passed on through reproduction, the mutations accumulated in the cell nucleus with increasing age disappear with the natural death of the organism. Only a small percentage of the spontaneously occurring mutations have positive effects, many mutations remain silent or express themselves only minimally or gradually. Mutations have also been artificially induced by gene manipulation since the end of the 20th century.
Many of the mutations that have accumulated over the years can only have a negative impact on the organism at some point in time. This can result in dysfunction of organs or in various vine diseases such as Mauke Express (cancer) and in extreme cases lead to inability to live. Since mutations occur in the cell nuclei of the tissues, these are initially only occasional changes in the genetic material of the cells in the living organism, which are usually not yet noticeable or not serious. Each chromosome mutates independently, through the double homologous set of chromosomes in diploid organisms such as that grapevine each genetic information is duplicated, so that a mutation-related loss of function on only one chromosome can be compensated for by the genes of the other homologous (matching) chromosome. There are also cellular repair mechanisms that make certain mutations harmless or can compensate for negative consequences.
Common mutations on Rebstock concern the changes in the color of the berries due to a mutation-related interruption or impairment of the synthesis pathways of anthocyanins based. Therefore, the most original grape varieties must have had a blue-black berry color. Because only varieties with the complete synthetic route for the anthocyanin dyes in the berry skin can mutate into deficient mutants such as the violet, red, pink or yellow-green varieties. Such a mutant deficiency can, however, pass on its deficiency, so that later red-berry or white-berry varieties also served as starting varieties for further breeding lines. Variations due to mutations are also evident in the vigor of the vine, the morphology the leaves (Shape, size, depth and number of leaf lobes, density of hair, etc.) to the exaggerated (upright or inclined form of growth, banding), and last but not least on the grapes and berries (fertility, intensity of the anthocyanin coloring, size of grapes and berries, side grapes, berry density, berry shape, ripening period or Maturity date and taste or flavorings ).
Especially with very old varieties like Chasselas. Garnacha. muscatel. Pinot and Traminer Over the course of centuries, diverse variety clones have developed through mutations. Clones In the wine-growing sense, these are generally no longer 100% identical copies of the original plant, but rather mutations that are already slightly genetically modified by mutations or morphologically slightly different varieties. In principle, mutations can occur anywhere in any cell and in any tissue, but most mutations are invisible. They only become visible when, for example, they occur in the vegetation point of the winter bud, since a whole new impulse that contains the new properties grows again through cell division of the mutated stem cells. This is why it is also called a sprout or bud mutation. A clone that deviates or differs in some characteristics is also called Klonmutant,
For example, new clones have been discovered for centuries and (if the change, such as a different berry color, was found to be good), became conscious vegetative propagated. But such a change was not noticed and at pruning this sprout removed, then this mutation could not be passed on, since the change was only present on this bud or the later shoot. During the vegetative propagation of the varieties by mass selection, which had been practiced for centuries, new vines were created for the new vineyards from the rods cut in the vineyard, so that the variety of clones developed on site remained consciously or unconsciously for centuries and was able to develop further. Normally, mutation-related clone variants only differ gradually from the original grape variety type, but especially with very old grape varieties with a very long vegetative propagation history, individual clones can have developed considerably apart.
The plants then accumulated so many different mutations in independent somatic lines of development that they too morphological delimit. Noticeable special cases were usually given their own names, the mostly easily detectable changes in the berry color, the Maturity date, Flavors or the density of leaf hair. Other mutations are manifested by a changed ripening cycle such as a somewhat earlier or later ripeness, which was often expressed with the prefixes green for later ripeness or yellow for sweeter berries (green and yellow Orleans; Green, yellow, blue and red are grapes ). The mutation of the berry color in particular occurs quite frequently. With somatic chimeric berries of different colors can even appear on the same grape, in extreme cases there are berries Tressot Panache (panaché = mixed) even different colors on a single berry.
Particularly significant examples are very old mutations Pinot Blanc and Pinot gris as berry color mutants of Pinot Noir, the Frühburgunder (Pinot Précoce Noir) as a mature mutant of Pinot Noir, the Pinot Meunier (Black Riesling) as a very hairy somatic chimera of the Pinot Noir and the less hairy Samtrot, which is a partial reverse mutation of the Pinot Meunier to phenotype of the Pinot Noir, but genotypically still shows the characteristics of the Pinot Meunier. There are three recent mutants foundling and Roter Müller-Thurgau (of Müller-Thurgau ) such as Kernling (of Kerner ). Reverse mutations can also often be observed in the berry color. If individual, particularly striking traits were affected, such varieties resulting from mutations were often regarded as independent grape varieties with their own names, although these were not breeding products.
If the differences were not so noticeable, one spoke more of game types, variants or varieties within the variety, but the latter term Wild vines is reserved. Humans have deliberately selected mutations again and again, i.e. selected the best forms, varieties and variants and then systematically increased them. Mutations can result in larger genetic deviations from a vine a "new" variety can be defined, as it were, which, as in the examples above, is not generated by generative propagation seedling emerged. Conversely, some sibling varieties are the result of seedling propagation phenotypically so similar that they were often confused and treated like a variety, even though they were genotypisch are easy to separate.
Artificial mutations (mutation breeding) can be deliberately caused by ionic radiation or chemical treatment of pollen grains, berry seeds, cuttings, buds, cell suspensions or other tissue parts. With colchicine treatment, mutants with a tetraploid chromosome set (4n) can be generated. See also under DNA. molecular Genetics. Vines systematics and grapevine,