A sign promoting McDonald's "PLT" burger with a Beyond Meat plant-based patty at one of 28 test restaurant locations in London, Ontario, Canada. Image Credit: Reuters

McDonald's Corp. and Beyond Meat Inc. are expanding their partnership - a significant step forward for the fast-growing faux meat producer.

Fifty-two restaurants in southwestern Ontario will now serve the "P.L.T." sandwiches - plant, lettuce and tomato that feature Beyond Meat's pea-based patties - for 12 weeks starting Jan. 14.

"As we expand the test, we're continuing to listen to our guests across Southwestern Ontario and assess the appetite for a plant-based alternative within the McDonald's menu," Michaela Charette, head of Consumer Insights at McDonald's Canada, said in a statement.

Beyond shares jumped as much as 5.9% in early trading Wednesday. They tripled last year.

The companies announced in September that the world's largest restaurant chain would sell the sandwiches in 28 stores in Ontario in a test run.

"We're pleased that McDonald's customers have shared they are enjoying the delicious, plant-based burger," said a Beyond Meat spokesperson.

McDonald's also sells an imitation meat burger with a product from Nestle SA in Germany.

Beyond Meat has rapidly spread across the restaurant industry in recent years and now has products in more than 7,000 Dunkin' stores across the country, as well as at chains like Del Taco, Carl's Jr., and Denny's. McDonald's scale - with roughly 14,000 locations in the U.S. alone - represents a unique challenge and opportunity for the company.

Competitor Impossible Foods Inc. has already rolled out a hamburger at U.S. Burger Kings and this week announced that an Impossible Croissan'wich, a sandwich with the new Impossible Sausage, would launch in five test markets at the end of the month.

Impossible Foods, which makes a soy-based patty, had experienced shortages at times as it ramped up production to meet widespread demand, but announced a deal in July with global food producer OSI Group to expand production.