At a crossing or. breeding from varieties the parents are usually given in the form of "New variety = mother variety x father's variety" (see an extensive listing under the keyword new breed ). For example " Müller-Thurgau = Riesling (Mother) x Madeleine Royale (Father)". This is also referred to as crossing direction. This is important because much more cell material is transmitted from the parent to the embryos in the seeds, namely nucleus, plastids and mitochondria. By contrast, only the cell nucleus is passed on from the father's place (see also in detail under blossom ).
The mitochondria are cell areas with energy producing functions and their own DNA (Deoxyribonucleinacid, genetic material). The chloroplasts belong to the group of plastids. They have their own ribosomes (for the production of proteins) compared to the other plant parts and, like mitochondria, they also have their own DNA. This allows them to share regardless of the cell in which they live. Other plastids are amyloplastics (storage of starch), chromoplasts (attracting insects for pollen dispersal for pollination) and leucoplasts (chemical defense against predators).
Only by DNA analysis of the passed through the mother's chloroplasts, the crossing direction can be determined. For many varieties, but something has not been done. Sometimes the differences are not sufficient to be able to determine exactly the crossing direction. This was successfully done, for example, with the variety Cabernet Sauvignon ( Cabernet Franc = Mother variety x Sauvignon Blanc = Fathers) and at most crossings Pinot x Gouais blanc (or the other way around). For many other varieties, this has not happened yet, so the information should be considered with caution.
Pictures: Ursula Bruehl, Doris Schneider, Julius Kühn Institute (JKI)