Fungus could aid plant growth, reclaim oil sites

A natural fungus is showing remarkable abilities to promote plant growth under stressful conditions while nursing polluted soils back to health.

Researchers are finding the multitalented fungus called TSTh20-1 (TSTh), short for Trichoderma harzianum 20-1, could increase agricultural yields and decontaminate some of the most polluted petrochemical places on the planet.

“I think this is a huge innovation at this point…. This is a game changer,” said Tim Repas, one of several University of Saskatchewan researchers involved in finding plausible mechanisms for how the fungus functions.

“TSTh does everything at once. It saves a lot of steps and a lot of work,” he said.

“I think once we get the field trials completed, we’ll be able to show that this is the way forward.”

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The inspiration for the innovation was a humble dandelion growing by itself in some coarse tailings in Fort McMurray’s oilsands region.

“It just happened to be this plant surviving somewhere where it shouldn’t have been, and the thought occurred to check it for this,” said Repas.

“If that plant can do it, can we transfer that tolerance mouldability to anything else?”

Susan Kaminskyj at the University of Saskatchewan College of Arts and Science led the research team that discovered the innovation.

The group isolated an entophyte fungus from the roots of the plant in the tailings.

When its spores are applied to plants, those plants grow and thrive on the material that lacks detectable levels of plant nutrients and is also water-repellant.

“Plants that TSTh colonizes grow vigorously on coarse tailings as well as on oil-contaminated soil without additional fertilizer or extra water,” said Kaminskyj.

Repas said when they added the endophyte fungus to places where seeds were not germinating or poorly germinating, they suddenly saw 90 percent germination, comparable to potting soil.

That’s when researchers found the plants were degrading hydrocarbons.

This means that while remediating a site of hydrocarbons, researchers were getting plants to establish as well, said Repas.

“That’s what intrigued us so much about this. It’s cutting down the number of steps to get from a problem site back to something functional.”

In Kaminskyj’s laboratory, tomato seedlings treated with the fungus flourished on tailings without fertilizer.

The fungi are not transmitted through seed so each seed must be individually colonized.

“It turns out that it doesn’t have to be just dandelions. It can be tomatoes, squash, wheat, flax, lots of different things,” Kaminskyj said.

Repas said researchers favour agricultural species because they tend to be more sensitive, so if a tomato can survive in the harsh environment of a contaminated oil spill, then larger agronomic species should be better because of their larger rooting systems and greater resilience.

Researchers now hope to learn whether harvested plants from the oilsand sites are safe to consume when produced under real world conditions.

“If you’re growing tomatoes, for example, on a reclaimed well site, are they just as safe to consume and nutritious as the ones in the field?” asked Repas.

In terms of oilfield reclamation, scientists are most interested in establishing a cover crop on coarse tailings and other petrochemical-containing soils. It’s hoped that could help reduce erosion, increase petrochemical mobilization and degradation, and begin to create a healthy soil.

Future research will likely explore growing perennial forages such as alfalfa, which is deep rooting and increases soil nitrogen.

“It would also be interesting to test the honey compared to other alfalfa honey,” said Kaminskyj.

However, future tests would need to determine if feeding these remediation crops to animals is safe.

Researchers at Adaptive Symbiotic Technologies in the United States have conducted field trials around the world to enhance crop yields using TSTh and a proprietary mixture of microbes and fungi.

After five years of testing, they have documented success at growing plants exposed to stresses such as drought, salinity and temperature.

They have reported that after high-stress growing seasons, their treated seeds increased crop yields an average of 10 to 50 percent.

“They are growing a wide range of things including wheat, corn and leafy greens. One of the nice things having grown these crops is they’ve found the fungus doesn’t cause problems for consumption,” said Kaminskyj.

These innovative uses for TSTh could have far reaching impacts on large scale farming operations across Western Canada for growing food and feed, as well as the bioremediation of plants on dry, low-nutrient, hydrocarbon-contaminated soils.

“We grow a lot of wheat and imagine if we could increase wheat yields by 50 percent on the same amount of land.

“Wheat could potentially be grown on contaminated soils. The next question, of course, is could you eat that wheat?” Kaminskyj said.

Added Repas: “When you’re talking huge agricultural scales, even a yield increase of five to 10 percent is, of course, massive.”

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