Miniature Grapevine Speeds Research
by Holly Luka, CAHNRS Marketing & News Services Intern
Washington State University researchers are using a dwarf grapevine variety named Pixie to research potential solutions to industry problems.
“This is your lab rat for the grape world,” said Amit Dhingra, assistant professor of horticultural genomics and biotechnology. “With Pixie grape, you can advance and accelerate solution delivery to the stakeholders for the challenges they are dealing with in their vineyards.”
Pixie grape is a mutant of Pinot Meunier, a grape variety widely used in making Champagne. A genetic mutation in Pixie makes it insensitive to gibberellic acid, a plant hormone that regulates growth and development. This accounts for the plant’s small stature; a mature Pixie grape plant is only about 18 inches tall.
In addition to its small stature, when started from a cutting, Pixie starts to flower in about three or four months and then continues to produce flowers and fruits throughout the year. Most grape varieties flower for the first time during their second or third year and produce fruit only once a year thereafter.
“Pixie is a great candidate for research and education because of its small size,” said researcher Kathie Nicholson, a horticulture graduate student working in Dhingra’s lab. “It takes up a lot less room than a normal-sized plant.” The plant uses fewer inputs, such as water and fertilizer, meaning it is a cost-effective research tool.
Because Pixie matures so quickly, it also accelerates research. “Pixie is a very good surrogate to test the function of fruit-related genes because we are not waiting three to four years to see the effect of a gene,” Dhingra said.
There are several ongoing research projects utilizing Pixie in Dhingra’s genomics lab.
Graduate student Kathie Nicholson is investigating the effects of 2,4-D on grapes. 2,4-D is a systemic herbicide used in the control of broadleaf weeds. It is the most commonly used herbicide in the world, and the third most common in North America.
This herbicide is not used in the vineyard, but it is used on nearby crops, such as corn and wheat, to control weeds, and sometimes drifts on the wind into vineyards where it can damage plants. Nicholson is looking for grape cultivars with 2,4-D resistance. She hopes to identify the gene that gives certain cultivars that resistance and to then transfer that resistance gene to other grape varieties. “We want to see what kind of effect 2,4-D has on Pixie, and see if we can transfer or mutate that gene,” said Nicholson. “Then 2,4-D would no longer be a problem.”
Currently, two WSU undergraduates are working on research projects with Pixie. Tyler Armour, a senior in the viticulture and enology program, is working on a regeneration protocol for propagating Pixie grape. Instead of growing grapes from seeds or cuttings he is trying to grow shoots from single cells or plant “stem” cells.
Armour takes leaf tissue, wounds it by cutting it into strips, placing in on a growing media in a bath of growth hormones. “If you get the hormone ratio right, you can get the cells in the leaves to start thinking they’re shoots, and get shoots growing from single cells,” said Armour. “In order to introduce new genes or alter existing genes to help solve growing issues, you need to be able to introduce the new genes at a single-cell level, so the entire plant has the new gene.”
Armour’s research is being funded by an Auvil Fellowship and a CAHNRS Undergraduate Research Grant. Another viticulture and enology senior, Dane Scarimbolo, received a CAHNRS Undergraduate Research Grant for his research on Pixie grape.
Scarimbolo is isolating and sequencing the gibberellic acid-sensitive gene that, when mutated as in Pixie and other plants, causes dwarfing. Scarimbolo’s research opens up the possibility of mutating the gene in particular grape varieties.
“We want to dwarf, for instance, Cabernet and Chardonnay for research,” said Scarimbolo. “We want something that we can grow and have results in three months in greenhouse testing.”
This article originally appeared in the Voice of the Vine newsletter.
More information
Learn more about research in Dhingra's lab by visiting genomics.wsu.edu.
Check out this short video featuring Dhingra and members of his lab talking about their work with Pixie grape: http://bit.ly/aVy4vQ