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mutation

mutazzione (I)

Under mutations (from Latin mutare "change, transform") one understands spontaneously in the nature occurring changes of the genetic information in the genome of the nuclei of plant and animal organisms, which play an important role in the evolution. These usually occur selectively (point mutations), but can also be larger DNA segments include (deletion, insertion, chromosome breaks). If the mutations in the germ line are successful, they are passed on to the next generation. If the organism is not cloned or propagated by reproduction, the mutations accumulated in cell nuclei with age disappear with the natural death of the organism. Only a small percentage of spontaneous mutations cause positive effects, many mutations remain silent or express minimal or gradual. Mutations have also been artificially induced since the end of the 20th century by gene manipulation.

negative effects

Many of the mutations accumulated over the years can at some point only later adversely (negatively) affect the organism. This can result in dysfunction of organs or in diverse vine diseases such as Mauke (Cancer) express and in extreme cases lead to the 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 usually not conspicuous or not pronounced. Each chromosome mutates independently, due to the double homologous set of chromosomes in diploid organisms such as the grapevine For example, every genetic information is duplicated, so that a mutation-related function loss on just one chromosome can be compensated by the genes of the other homologous (coincident) chromosome. In addition, there are also cellular repair mechanisms that can neutralize certain mutations or compensate negative consequences.

frequent changes

Common mutations on the Rebstock concern the changes in the color of the berries, which are due to a mutation - related interruption or impairment of the synthesis pathways of the anthocyanins based. Therefore, the most original grape varieties must have had a blue-black berry color. For only varieties with the complete synthesis pathway for the anthocyanin dyes in the berry skin can mutate to deficient mutants such as the violet, red, pink or yellow-green varieties. However, such a deficient mutant can pass on their lack, so that later also red berry or white berry varieties were used as starting varieties for other breeding lines. Mutationsbedingte variations are also reflected in the vigor of the vine, the morphology the leaves (Shape, size, depth and number of leaf lobes, density of hairiness, etc.), to the exaggerated (upright or inclined habit, banding), and last but not least on the grapes and berries (fertility, intensity of anthocyanin color, grape and berry size, side grape, berry density, berry shape, maturity or Maturity date and taste or flavorings ).

Mutational variants

Especially with very old varieties like Chasselas. Garnacha. muscatel. Pinot and Traminer Over the course of centuries mutations have produced a variety of varietal clones. Clones In the viticultural sense, no 100% identical copies of the original plant are usually more, but by mutations already genetically slightly modified mutants or morphologically slightly different varieties. In principle, mutations can happen anywhere in every cell and in every tissue, but most mutations are invisible. They only become visible when they occur, for example, in the growing point of the winter bud, which, in turn, results in cell division of the mutated stem cells, resulting in a whole new shoot containing the new properties. This is why they are called also bud or bud mutation. One different in some characteristics or strongly different clone is called also Klonmutant,

Thus, for centuries, new clones have been discovered and, if the change, such as another berry color, has been found to be well-known vegetative propagated. But was such a change not noticed and when pruning removed this shoot again, then this mutation could not be passed on, since the change was exclusively on this bud or the later shoot was present. In the centuries-long practiced vegetative propagation of the varieties by mass selection, the vines cut in the vineyard new vines were founded for new vineyards, so that the locally developed clone variety for centuries consciously or unconsciously preserved and could evolve. Normally, mutation-dependent clonal variants differ only gradually from the original grape variety type, but especially in very old grape varieties with a very long vegetative propagation history, individual clones may have disintegrated quite considerably.

Beer Color

The plants have then accumulated so many different mutations in independent somatic lineages that they too morphological delimit. Conspicuous special cases were usually provided with their own name, the mostly easily detectable changes in the berry color, the Maturity date, Flavors or density of leaf hair. Other mutations are manifested by a change in the maturity cycle, such as a slightly earlier or later maturity, often expressed by the prefixes green for later maturity and yellow for sweeter berries (green and yellow Orleans; Green, yellow, blue and red are grapes ). Especially the mutation of the berry color occurs quite often. In somatic chimeric may even occur on the same grape different colored berries, in extreme cases, there are as in Tressot Panaché (panaché = mixed) even different colors on a single berry.

Pinot varieties - Pino Blanc, Pinot Gris, Pinot Noir, Pinot Meunier, Pinot Noir

Particularly significant examples of very old mutations are Pinot Blanc and Pinot gris as berry mutant of the Pinot Noir, the Frühburgunder (Pinot Précoce Noir) as a precocious mutant of Pinot Noir, the Pinot Meunier (Black Riesling) as a strongly hairy somatic chimera of Pinot Noir and the little hairy Samtrot, which is a partial reverse mutation of Pinot Meunier to phenotype of the Pinot Noir genotypically but still has the characteristics of Pinot Meunier. There are three more recent mutants foundling and Red Muller Thurgau (from Müller-Thurgau ) such as Kernling (from Kerner ). In the case of the berry color, one can often also observe reverse mutations. When some particular salient features were involved, such mutant species were often considered to be separate grape varieties with their own names, although these were not breeding products.

Varieties / varieties

If the differences were not so conspicuous, one spoke rather of varieties, variants or varieties within the variety, but the latter term Wild vines is reserved. Humans have deliberately selected mutations, that is, selected the best forms, varieties and variants, and then deliberately further propagated them. By mutations can thus with larger genetic deviations from a vine quite a sort of "new" variety are delimited, which, as in the above examples, not from generative propagation by means of seedling emerged. Conversely, many sibling varieties that have emerged from seedling propagation can be seen phenotypically so similar that they are often confused and treated like a strain, though they do genotypisch are easy to separate.

Artificial mutations (mutations breeding) can be deliberately induced by ionic irradiation or chemical treatment of pollen grains, berry seeds, cuttings, buds, cell suspensions or other tissue parts. With colchicine treatment, mutants with tetraploid chromosome set (4n) can be generated. See also under DNA. molecular Genetics. Vines systematics and grapevine,

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