Your Phenotype Is Showing

In my seven years (this month) with NGRA, I’ve found that few topics can stop a conversation quicker than genetics. Start talking to people about the ins and outs of marker-assisted grape breeding and watch the curtain fall across their attention span as they mentally check out. But genetic research is critical to the sustainability of the grape and wine industry! So, when I ran across two beautiful explanations this month of genetic concepts, I thought I’d share.

Meg Maker has a way with words. A recent essay in her online publication, Terroir Review, caught my attention with this subhead: “Wine is a constellation of traits fixed and mutable.” She goes on to eloquently explain the distinction between genotype and phenotype as it relates to a wine’s expression.

Reviewing wines, she says, can be like describing a meadow of flowers. In a meadow, “each flower has an essential character, a DNA, and a conditioned character, a personality. In botany those are called genotype and phenotype. The first dictates what the flower can be based on its genetic coding. The second describes what the flower has become based on its environmental conditions.” (Emphasis is mine.) In describing a wine, she writes, the wine critic must “first describe the ur-wine,” akin to the type of flower that comprises the meadow, “then say how it differs from all wines of its type.”

Genotype is “a recognizable signature,” Meg continues. To a grape breeder, that would be a vine’s genetic coding for the number of chromosomes, the size and shape of its leaves, color of its berries, etc. Phenotype is shaped by the environment and things like vine management and even winemaking. It is “the character (the wine) earns from its life in field and bottle,” Meg writes. Although her essay is on wine, it applies to grapes—or the ur-grape, as she might say.

The Ask Dr. Universe blog, which answers children’s questions about the natural world, also recently illustrated the concept of phenotype—not by name, but in an explanation of how plants respond to their environment. “A plant’s roots and shoots know which way to grow because the plant can sense gravity. It responds by growing away from gravity or toward it—called tropism. Plants also sense light, water and touch. They automatically grow toward or away from those things,” writes Dr. Universe (who is a cat in a lab coat).

And in a return to Meg’s meadow, Dr. Universe cites flowers as an example of how plants evolve to adapt to their environment. “Plants haven’t always had flowers,” says Dr. Universe. “Millions of years ago, some plant leaves started growing around the plant’s seeds. That helped those plants survive. They passed on their weird leaves to their baby plants. Eventually, those leaves became flowers.”

In the context of plant breeding, the Dr. Universe example illustrates spontaneous mutations that eventually change a plant’s genotype. Whether using traditional breeding, the hit-or-miss method of crossing the pollen of plants with traits of interest employing genetic markers to guide traditional breeding or even making deletions in DNA via gene editing, breeders seek to make similar genetic changes in plants—changes that could happen in nature—on a much shorter timeline. It’s these types of changes that have given the grape and wine industry innovative and economically important new cold-hardy and disease-resistant varieties. And it’s this type of work in grape genetics that will help us weather the changes climate change will continue to bring.

Armed with this information, feel free to engage future dinner companions in conversations about the value of genetics research to our industry. And if their eyelids start to droop, don’t worry—it’s just their phenotype showing!