This series of posts will highlight the plants that help you celebrate the Yuletide season.
Grapes, really? Sure, you could eat them and even use them as part of a centerpiece at your table, but today (tonight) it’s all about the champagne. This bubbling beverage has been synonymous with celebration for centuries. There’s plenty of history, chemistry and geography associated with this drink, but this post is about the plant biology. Here’s more on the fruit in your flutes.
The scientific name for grapevines is Vitis vinifera, but there are numerous cultivars used in winemaking. Within the strictest definition of champagne, the grapes used for production are a mixture of the Pinot Noir, Chardonnay, and Pinot Meunier varieties. While there may be some leeway on the grape composition of champagne, the propagation of these cultivars and their prized traits are more tightly controlled by humans. Nevertheless, grapes have some interesting genetic and developmental characteristics.
Grapevines are vegetatively propagated instead of grown from seeds. This takes advantage of the developmental plasticity of plants in order to tame their propensity for genetic diversity. Making new vines from older ones with desirable traits can be done in a few different ways. Cuttings from vines can be coerced to make their own root system and become new individual plants. This is an efficient way of multiplying a lot of new vines of a desired cultivar. Cuttings can also be grafted onto an existing rootstock. As with apples, the scion (the plant part joined to the rootstock) will determine the type of fruit produced. Grafting a new variety onto established rootstocks offers a relatively quick way for vineyards to change over production to a new type of grape. If only a few new vines are needed to replace older or damaged vines, new vines can be layered by burying a portion of the growing vine until it forms its own root system that can support an entire plant.
These types of propagation limit the diversity of traits that control things like flavor, but no system is perfect. It still involves making copies of each cell’s DNA with every cell division, which means spontaneous mutations can still occur. Again because of the characteristic developmental properties of plants, these mutations can affect the type of fruit produced. Pinot Meunier provides a particularly interesting example of how these concepts come together. Those plants are actually chimeras in which some cell layers have distinct genetic material from others. In the case of Pinto Meunier, the type of chimera is a periclinal chimera (plant biology word of the day). It may sound more like a Halloween monster instead a New Year’s Eve party, but these interesting genetic combinations are quite stable when plants are vegetatively propagated.
When you are toasting to Auld Lang Syne tonight, keep in mind there is a lot of science in your sip.