Canadian and Chilean scientists have identified more than 1,000 genes involved in how flax responds to nitrogen stress. The discovery could eventually help breeders create crops that need less fertilizer and cost farmers less to grow.

The next breakthrough in farming may be hiding underground.

At Agriculture and Agri-Food Canada’s Charlottetown Research and Development Centre, scientists have been studying what happens to flax plants when one of their most important nutrients becomes scarce. Their discovery: some varieties don’t simply tolerate a shortage of nitrogen. They change how they grow.

Their roots expand. Their shoots continue developing. And deep inside the plant, hundreds of genes change their activity. Now researchers believe those genetic differences could provide a roadmap for breeding flax varieties that thrive with less nitrogen fertilizer — a potentially significant development for farmers facing rising input costs and an agricultural sector under pressure to reduce its environmental footprint.

The research, led by Agriculture and Agri-Food Canada scientist Dr. Bourlaye Fofana and Dr. Braulio Soto-Cerda of Chile’s Universidad Católica de Temuco, identified more than 1,000 genes that respond when flax plants experience nitrogen stress.

The bigger opportunity is figuring out which of those genes help make a plant more efficient.

Why fertilizer efficiency matters

Flax — also called flaxseed or linseed — is a relatively small crop with an outsized reputation. Its brown or golden seeds are rich in omega-3 fatty acids, fibre, and lignans, while Canada ranks among the world’s major flax producers.

But like many crops, flax needs nitrogen to reach its potential.

Farmers typically supply that nitrogen through fertilizer. The problem is that fertilizer represents a significant input cost, and plants don’t necessarily absorb all of the nitrogen applied to a field.

Nitrogen that isn’t used by the crop can move into waterways through runoff or be released into the atmosphere as greenhouse gases.

That has created a deceptively simple question for plant scientists: What if crops could produce more with less?

One answer may lie in their roots.

A plant that knows how to search

Fofana maintains a collection of flax germplasm in Charlottetown — a genetic library containing materials such as seeds, plant tissues, and DNA.

Researchers selected two contrasting types of flax seedlings from that genetic diversity. One was naturally efficient at growing when nitrogen was scarce. The other struggled under the same conditions.

They then grew the plants under both normal and nitrogen-deficient conditions.

The difference was striking.

The nitrogen-efficient plants maintained greater root and shoot biomass. More intriguingly, when nitrogen became scarce, they expanded their root systems.

In effect, the plants appeared better equipped to search for what they needed.

“The root system is like the plant’s nervous system,” Fofana says. “Crops that grow more extensive and flexible roots can find and use more nitrogen available in the soil.”

For breeders, that adaptability is especially interesting. A plant capable of developing deeper or more extensive roots when nutrients become scarce could potentially extract more nitrogen already present in the soil instead of depending as heavily on additional fertilizer.

“If you can find the genes that support better root systems that can dig deeper in the soil when less nitrogen is available, that is very helpful for breeders,” Fofana says.