Beyond Meat may have lost Tim Hortons, but it has partnered with another popular fast-food chain in Canada: McDonald's.

The iconic burger chain announced Wednesday it will test a new plant-based burger known as the P.L.T. — plant, lettuce and tomato — in 28 McDonald's locations in southwestern Ontario starting Monday.

The patty would be made of Beyond Meat, the plant-based protein that entered the scene this year on grocery store shelves and in various fast-food chains. Canadian coffee and doughnut chain Tim Hortons launched several versions of the product earlier this summer, but has since scaled back availability from across the country to just Ontario and British Columbia.

It's not immediately clear why McDonald's has selected Canada alone to be the test market for its first plant-based sandwich for the North American market. Of the 28 locations, 18 will be in London, Ont., while the rest will be in other communities elsewhere in southwestern Ontario.

Most of the locations with the burger will be in London, Ont., with a handful elsewhere in southwestern Ontario. (Scott Galley/CBC)

California-based Beyond Meat Inc. went public earlier this year, and it quickly became one of the fastest-rising new stocks of the year, although it has pulled back from its recent highs over concerns its growth may be unsustainable, and some criticism over how healthy the patties are.

Shares in Beyond Meat jumped 13 per cent in premarket trading on the stock market when news of the McDonald's partnership came out.

The promotion, a pilot project set to last to the end of the year, represents the burger chain's biggest push into plant-based eating. The chain previously offered a soy-based veggie burger at the turn of the century but soon halted production due to slow sales.

If successful, it could become a permanent offering at some of the chains 38,000 locations in more than 100 countries around the world.

The burger will be priced at $6.49 Cdn.

The launch also comes a few months after McDonald's fierce rival Burger King launched its own meatless burger, in partnership with Beyond Meat's biggest competitior to launch the Impossible Whopper last spring.

Beyond Meat is the core ingredient in a number of fast-food offerings, including meatballs, chicken and other forms at various other fast-food chains including A&W, Subway and KFC.

McDonald's says its version won't taste the way Beyond Meat burgers at other chains and grocery stores do, because the chain says it has been "working on its recipe" for a while.

"We know we're not first," Michaela Charette, the company's head of consumer insights, told The Canadian Press. "We've been taking our time to get it right."