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Contrary to previous assumptions, the White Riesling, usually simply called "Riesling", did not evolve from the Red Riesling, but the other way round. This is what researchers at the Julius Kühn Institute (JKI) in Siebeldingen found out.
"Since spontaneous mutations of the red grape to white berries were observed again and again, but never vice versa, it was assumed that the `Red Riesling` was the original grape variety. However, the examination of the chromosome sets of the 'Red Riesling' genome finally gave us certainty: the chromosome sets that lead to colour in the red variety originally come from the white-berry parent. Consequently, the mutation to red must have happened in the 'White Riesling'," explains Dr Franco Röckel from the Julius Kühn Institute.
He also found out that the genetic information for the red colour comes from the white-berried White Heunisch, one of the parents of the Riesling. The other parent is a seedling of 'Traminer' and Vitis sylvestris with unknown berry colour.
Dr. Röckel and his colleagues assume that the mutation arose uniquely in White Riesling and is therefore due to a mutated plant. But why red Riesling always mutates back to white remains unexplained.
(al / Source: JKI; Photo: JKI/Röckel)