MONDAY IN THE VINEYARD SERIES
How new grape varieties (crossing and hybrids) and clones are created and propagated.
You might find this article useful if you are a curious wine enthusiast or if you are currently preparing for your WSET Diploma D1 or WSET 3 examination. In that case, don't forget to check out our FLASHCARDS as well.
Vine propagation can be achieved through various methods, depending on the desired outcome. There are two main categories of vine propagation:
1. Sexual Reproduction = Cross-Fertilization
Sexual reproduction occurs when the pollen from a male part of one grape variety's flower fertilizes the female part of another grape variety's flower. The pollinated flower develops into a grape with seeds. Pollination can happen naturally or be induced in a controlled environment to cross two selected varieties. If the seeds are planted, a new grape variety will be generated that is genetically different from its parent plants, much like human children are not genetically identical to their parents.
The new grape varieties resulting from sexual reproduction are referred to as either crossings or hybrids, depending on the species of their parents.
CROSSINGS: These are new varieties resulting from cross-fertilization between two grape varieties of the same species. For example, Pinotage is a crossing of Pinot Noir and Cinsault, or Cabernet Sauvignon is a crossing of Cabernet Franc and Sauvignon Blanc. All parent plants belong to the Vitis Vinifera species
HYBRIDS: These are new varieties resulting from cross-fertilization between two grape varieties of different species. For example, Vidal Blanc is a hybrid of Ugni Blanc (Vitis Vinifera) and Rayon d'Or (a Hybrid variety resulting from Seibel 405 and Seibel 2007 - Aramon du Gard).
Creating a new grape variety through cross-fertilization for commercial use is a costly and time-consuming process. It involves growing many plants, waiting for them to yield fruits over several years, and then monitoring them extensively to evaluate their worth for commercial release. If deemed suitable, these new varieties are registered in the OIV catalogue as new grape varieties.
While the goal of sexual reproduction is to produce a new variety with beneficial traits inherited from both parent vines, achieving this can be challenging. For example, Müller-Thurgau resulted from crossing Riesling and Madeleine Royale with the intention of combining Riesling's fruit quality and Madeleine Royale's high yield. However, despite its commendable productivity, Müller-Thurgau is widely recognized to lack the exceptional quality potential exhibited by Riesling.
2. Asexual Reproduction = Vegetative Propagation
In plants, several forms of asexual reproduction exist, where new individuals are generated from vegetative parts of a parent plant, such as stems, without involving the formation and fusion of seeds. These methods are collectively known as vegetative propagation.
Unlike sexual reproduction, which involves the combination of genetic material from two parent plants, vegetative reproduction typically results in offspring that are genetically identical to the parent plant.
However, during the growth process, spontaneous genetic mutations can occur. These mutations may lead to small differences, which can be either positive or negative. Positive differences may include improvements in fruit quality, a slightly different aroma profile, thicker or thinner skin, or better disease resistance. Plants exhibiting positive mutations can be selected for further propagation and are then classified as new clones. This selection process is known as Clonal Selection (to know more about clonal selection and mass selection read this article) Plants of the same clone share identical characteristics while showing slight differences from vines of a different clone. These differences between clones are generally so minor that they are still considered to be the same grape variety.
Some grape varieties, having existed for a long time, have had ample opportunity for many genetic mutations, resulting in the development of numerous clones. A prime example is Pinot Noir, which boasts over 1000 clones. However, not all of them are commercially available or permitted to be planted in all regions. For instance, France currently allows 47 Pinot Noir clones for commercial use. Some well-known Pinot Noir clones include Pinot Noir Clone 115, Pinot Noir Clone 667, Pinot Noir Clone 777, and Pinot Noir Clone 943, among others.
In rare cases, genetic mutations result in such significant differences that they are considered as an entirely new grape variety, even though, strictly speaking, they are clones of the original grape variety. Pinot Blanc and Pinot Gris are famous examples of this phenomenon, having originated as genetic mutations of Pinot Noir.
IN SUMMARY, vegetative reproduction can lead to three options:
SAME VARIETY AND CLONE: Usually, no genetic mutations occur, and the new plant is identical to its parent.
NEW CLONE: Occasionally, genetic mutations result in minor differences. For example Pinot Noir Clone 115, Pinot Noir Clone 777, Pinot Noir Clone 943, and others.
NEW VARIETY: Rarely, genetic mutations cause significant differences, resulting in a whole new grape variety. For example Pinot Gris.
The most common methods for vegetative reproduction used in viticulture are cuttings and layering. For further information on these methods, including their advantages and disadvantages, please read this article.
I hope you found this article both useful and insightful. If you enjoyed it, make sure to stay tuned for my next article. Join me after the summer break on the first Monday of September for more fascinating insights!
Happy week and happy studying,
Nicky