At a crossing respectively. breeding of varieties the parents are usually given in the form of "new variety = mother variety x father variety" (see an extensive list under the keyword new breed ). For example " Müller-Thurgau = Riesling (Mother) x Madeleine Royale (Father)". This is also known as the crossing direction. This is important because the mother variety transfers a lot more cell material to the embryos in the seeds, namely the nucleus, plastids and mitochondria. However, only the cell nucleus is passed on from the father variety (see also in detail under blossom ).
The mitochondria are cell areas with energy-generating functions and their own DNA (Deoxyribonucleic acid, genetic material). The chloroplasts belong to the group of plastids. Compared to the other parts of the plant, they have their own ribosomes (for the production of proteins) and, like mitochondria, also have their own DNA. This allows them to share regardless of the cell in which they live. Other plastids are amyloplasts (storing starch), chromoplasts (attracting insects for the purpose of pollen transfer for pollination) and leukoplasts (chemical defense against predators).
The direction of crossing can only be determined by DNA analysis of the chloroplasts passed on by the mother variety. This has not yet been done for many varieties. Sometimes the differences are not sufficient to determine the exact direction of the crossing. This was successfully done for the variety, for example Cabernet Sauvignon ( Cabernet Franc = Mother type x Sauvignon Blanc = Father variety) and at most crossings Pinot x Gouais Blanc (or the other way around). However, this has not yet happened with many other varieties, so the information should be viewed with appropriate caution.
Images: Ursula Brühl, Doris Schneider, Julius Kühn Institute (JKI)