Giles E.D. Oldroyd

So this soybean plant can get almost all of its phosphate and the totality of its nitrogen needs met through these beneficial microbial associations.

And that provides a free and sustainable means to support its crop production.

And out in nature, most plants are engaging with one or more of these beneficial microorganisms to help them capture these limiting nutrients from the environment.

But in agriculture, it's a really different situation.

There, we're applying these nutrients at high concentrations in the form of inorganic fertilizers to support our crop production.

And while inorganic fertilizers have underpinned global food security for the last 60 years, they cause significant environmental pollution, they cause significant greenhouse gas emissions, they contribute to a lot of the costs in our crop production, and at the other end of the spectrum, smallholder farmers lack access to those fertilizers and their productivity suffer as a result.

For all of these reasons, myself and my colleagues in the ENSA project are working to eradicate or at least greatly reduce our reliance on inorganic fertilizers.

To do that, we want to make all of our crop plants, particularly our cereal crops, behave like this soybean plant, able to get their nutrients through these beneficial microbial associations.

Now, the fungal symbiosis is not limited to legumes like that soybean.

It's actually pretty widespread within the plant kingdom, and it's already present in our cereal crops.

However, when we fertilize our fields, the crop doesn't engage with the fungus.

Why pager the fungus with carbon if the nutrients are not limiting?

So while soils in natural ecosystems are packed full of a complex network of these mycorrhizal fungi fed by their host plants, our agricultural soils are greatly depleted for these beneficial fungi.

If we want to really maximize the utilization of this fungal symbiosis in agriculture, then we need to get our crop plants to gauge with the fungus much more proactively, and even when we fertilize our fields.

If we can do that, then we can reduce the levels of fertilizers we use, and we'll lose less of those nutrients out into the environment.

So to achieve that, we set about identifying the genetic regulators that control when the plant engages with these beneficial fungi.

and we discovered that these proteinaceous regulators are only present when the plant is starved for nutrients.

And we were able to rewire that system so that now the plant engages with the fungus much more proactively, and even when the plant is fertilized.

In our field trials, we find that these rewired barley plants get 10 times as much fungus inside their roots.

That's a lot more fungus in the crop, but it's also a lot more fungus out there in the field.