Canadian Light Source aids agriculture projects

The synchrotron at Saskatoon is giving researchers a new view of old subjects

Chithra Karunakaran prepares a plant for imaging at the Canadian Light Source.

Agriculture researchers facing difficult challenges might want to consider shining a light on their problems — a really bright light.

The light in question is the Canadian Light Source, a synchrotron located at the campus of the University of Saskatchewan in Saskatoon.

Researcher Chithra Karunakaran spoke recently during a Zoom presentation hosted by the University of Manitoba. She said agriculture should be aware of what the light source can help the sector accomplish.

“It’s a great tool,” Karunakaran said. “There are some real advantages coming in using the synchrotron and agriculture is one of our strategic areas. We want to grow in this field so if you’re an ag researcher and you have some challenging problems we welcome you to CLS where a group of people like me are willing to see if we can solve them.”

Peering deep

When you get an X-ray, the technician puts you into position and then says, “hold your breath for about five seconds.” The machine gives a long buzz as it beams the X-rays through you. It’s a long exposure and if you move it blurs the image. Hospital X-rays will show you bones, teeth and some hard lumps but there is a lot of detail you’re not going to get. For that you need a synchrotron like the Canadian Light Source.

“A hospital X-ray is not sensitive to soft tissue like lungs,” Karunakaran said. “The synchrotron has different properties so it shows soft tissue and because the light is extremely bright we can use high-resolution detectors, not possible in a hospital X-ray.”

The enormous synchrotron that can produce light brighter than a million suns. photo: Gord Leathers

And it is a bright light. A synchrotron light beam is more than a million times brighter than a sunbeam and, like the sun, there is a lot more in it than the visible light that the human eye can see. There are qualities of infrared, soft X-rays and hard X-rays that help us see things that we’ve never seen before. And in detail that we only could imagine up until a few years ago.

It’s not a small piece of equipment. It occupies a substantial building at the University of Saskatchewan campus. It consists of a number of different parts starting with an electron gun. The gun fires a stream of electrons into a linear accelerator that feeds them microwave energy to get them going close to the speed of light. From there they enter a booster ring where they’re bombarded with more microwaves as they tear around the ring. Once they’ve reached their energy capacity they’re fed into a larger storage ring where powerful magnets guide them around the circle.

Electrons, like a fast race car, like to travel in a straight line. If you take a fast car into a sharp turn the tires squeal. When the magnets turn these highly energized electrons they do something similar but instead of emitting sound they emit particles of light called photons. These photon beams shine along a straight beamline into a work station where they can be filtered. A research subject placed in the filtered beam reacts to the light and the reaction is analyzed by a computer.

What it sees

The computer can show you all kinds of things. For example, a dried sunflower head can be probed by a focused beam of X-rays, slicing through it layer by layer. The computer puts together a composite image of the flower and you can see a cross-section in any plane you select, as well as different tissues and different structures.

“Another example is root imaging,” Karunakaran said. “There are a lot of technologies available to look at plants but not to see what’s going on below the soil. The X-rays can penetrate the soil so we take a plant in a pot, we image them both and then we artificially remove the soil so you can see the root system.”

The structure of gas bubbles in bread dough, as revealed by the Canadian Light Source. photo: Canadian Light Source

Up until now, the plants would be uprooted and the roots washed clean. The actual root architecture would simply collapse but, with the synchrotron image you can see every root of every size and every bend. You can see exactly how the plant set its roots to scavenge nutrients and water from the soil right down to every root angle. A plant breeder looking for drought tolerance has a good idea what a plant has to offer on the basis of root density and architecture.

Another big advantage of the synchrotron light is the brightness and how well it captures images in a dynamic system such as bread dough. A University of Manitoba team led by Martin Scanlon is using the Canadian Light Source to do X-ray tomography of bread dough on the rise.

“They used their laboratory X-ray equipment to see how the bubbles were developing as a function of gluten content and sodium content,” Karunakaran said. “To take a 3D image was taking about eight seconds and by the time the bubbles developed from smaller into bigger they don’t have a lot of data points to see how the bubbles developed in softer bread. But in the synchrotron you can go 1,000 times faster.”

The images she presented on a slide are dazzling, row upon row of bubbles in three dimensions showing how well they were distributed throughout the dough and how evenly the bread would rise. These are important factors in food quality that farmers and plant breeders need to know about the quality of protein in the plant. Other people are working on noodles to see how protein affects texture.

These are just a couple of examples of what this technology can do in agriculture. There are also groundbreaking studies underway in medicine, both human and veterinarian, as well as soil science, chemistry and materials science, she said.

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