Graduate student Laise Moreira loves grapes, and it’s a good thing she does because she spends quite a lot of time with them. With her team, she is researching table grapes for Minnesota in the hope of developing a grape that is seedless, cold-hardy, and flavorful. Most seedless cultivars currently on the market were bred for warm climates, dry conditions, or mild winters, making them unsuitable for Minnesota’s climate.
Laise looking at red table grapes in vineyardTo develop seedless grapes, Moreira is using a technique called ‘embryo rescue.’ The first step starts with choosing parents that are most likely to produce the best offspring adapted to the harsh Minnesota winters. “Hardiness is the biggest struggle because of the parent grapes, so right now we are picking parents based on hardiness,” Moreira explained.
Once parents are selected, Moreira performs an emasculation, or removal of the stamen and anther of the flower, to prevent the plants from self-pollinating. After, the flowers are covered to keep out any unwanted pollen from other plants.
At the veraison phase, when at least 25% of the grapes are soft to touch and changing color, Moreira comes back to collect ovules from the fruit and place them into growth media to grow the embryo. A few months later, she dissects each ovule one by one. “Every year you do this you will have 2,000-3,000 to open. You can’t just do this with your eyes, you need to use a microscope to see the embryo because it’s really tiny and because everything inside is white. It’s difficult to separate what is an embryo and what isn't,'' Moreira explained. This tiny embryo will grow into a new, unique plant.
After three months in a test tube, the new plants can be transferred to the greenhouse before being planted outside. “Then we cross our fingers and wait for four to five years, and we will have the fruit!”
It’s because of this long waiting period that Moreira has begun another project. Teaming up with Professors Adrian Hegeman and Matthew Clark, Moreira has begun to look at flavor compounds in cold-hardy grapes to develop a genetic map that identifies where on the chromosome the ‘grape’ flavor exists. Wine grapes are used as a model since little information exists about table grape populations. “There is a lot of information about flavor for wine grapes, but not a lot for table grapes,” Laise explained.
“This research could help shorten the selection process for breeding so we are able to spend more time on the cultivars that you want and less time on the ones that you don’t,” Moreira expressed. “If we develop markers that identify how the grape tastes, we can make selections before we even see the fruit. With the right selections, it could save a lot of time and money.”
Laise Moreira’s work is supported by the Minnesota Department of Agriculture and VitisGen. To learn more about her work and the work the Grape Lab is doing please visit, enology.umn.edu