Giles E.D. Oldroyd

So now we can control when the plant engages with these beneficial fungi.

The next step for us is to test, does that mean we can lower the fertilizer levels and still maintain good production?

I believe this is a first step to really getting that fungal association working for us much more proactively in agriculture.

And that's going to be really important, especially for how much phosphates we have to apply to our fields.

But if we're going to really cure our addiction to inorganic fertilizers, we also need the nitrogen-fixing bacterial symbiosis.

Now, unfortunately, the nitrogen-fixing symbiosis is limited to legumes like that soybean and their relatives.

So we are working on transferring that nitrogen-fixing symbiosis from legumes to our cereal crops.

Myself and my colleagues have spent the last 30 years undertaking genetic dissection to try to identify all the genes that in soybean allows it to engage with those nitrogen-fixing bacteria.

During that time, we've identified many genes that are involved in that process.

But surprisingly, we haven't yet identified a single gene that is novel to that soybean plant.

In fact, the genes are already present, most of them are already present in our cereal crops.

Let me give you an example, the symbiosis signaling pathway.

This is a set of proteins that are expressed on the cells on the surface of that soybean root that allow the soybean plant to recognize the nitrogen-fixing bacteria out in the soil.

When they recognize the bacteria, they oscillate their calcium in the nucleus.

This is essentially the cell saying, I've seen these beneficial bacteria out in the soil.

Now turn on the gene expression that's necessary to let those bacteria in.

This symbiosis signaling pathway that in the soybean plant allows it to perceive the nitrogen-fixing bacteria is already present in our cereal crops.

And that's because it's the same signal transduction pathway that allows all plants to recognize mycorrhizal fungi.

What we now understand is that when legumes evolved this capability to engage with nitrogen-fixing bacteria, they didn't invent anything new.

They used the preexisting genetic components associated with engagement with beneficial fungi to also allow engagement with beneficial bacteria.