Probing plant secrets in order to feed a changing world

By Brian Charles Clark

The flashing contraption: WSU’s phenomics camera.

PULLMAN, Wash. – With an impish grin, Mike Kahn recently led a group of visitors into an old greenhouse on the Washington State University campus in Pullman. Kahn is a scientist in WSU’s Institute of Biological Chemistry, home to a group of researchers probing the secrets of plant life to help ensure the world’s burgeoning population has enough to eat.

“Welcome to the future,” his expression seemed to say. Inside, the group of reporters and videographers was treated to a remarkable site: a boxy contraption moving over rows of small green plants, stopping at intervals and emitting flashes of colored light.

he contraption contains two cameras and literally looks at plants in a new way.

Too many gene possibilities

“In theory,” Kahn said, “we can breed by following the genes that contribute to the development of desirable traits in a plant.” “Desirable traits” is a sweeping term plant breeders use to describe everything from yield and size to disease- and drought-resistance.

“But for the foreseeable future, there is no technology that is going to get us to each gene, as there are on the order of 30,000 genes in each plant,” Kahn said. “That means there are a lot of possibilities. This is the problem breeders have. They need to sort through a lot of gene possibilities to find the ones they want.

“We are looking at plants in another way,” he said, “because there are certain things about the genes that can be evaluated by using cameras that can look at lots of whole plants rapidly and efficiently.”

Genetics + environment = phenomics

Welcome to the new science of phenomics: the study of phenotypes, which are the observable characteristics of an organism.

The phenotype is the result of a complex relationship between the organism’s genome – its specific set of inheritable characteristics – and its environment, which influences the expression of that genetic inheritance. Phenomics is critical because it connects the dots between an organism’s genetic potential and how it actually performs in a specific environment.

Phenomics and the use of modern data acquisition technologies to describe many phenotypes simultaneously is in its infancy. WSU’s phenomics center is one of a few in the world, and the light-and-camera instrument is the first of its type.

The WSU phenomics project pushes toward the breeders’ goal of assessing a plant’s genetics by actually subjecting plants to some of the environmental conditions growers and their crops are likely to encounter and measuring how they respond.

Measuring plant fluorescence

“It’s really welcome back to the future,” Kahn said. “For thousands of years, people have evaluated the utility of a plant by looking at it to assess things like fruit and kernel size and color – all the things that make a crop plant desirable. That’s sort of what we’re doing here” – he gestured at the flashing contraption – “but now we’re able to optically screen a large number of plants for specific traits.”

The underside of the phenomics camera.

The phenomics instrument works by emitting brief, bright flashes of light at plants in a dark growth room and then photographing the fluorescence the plants re-emit as a result. This fluorescence is a byproduct of photosynthesis. Chlorophyll in the leaves absorbs the flashes of light and then discharges the excess light energy.

Fluorescence is one of the ways that plants defend themselves, since too much light energy can cause damage. A great deal can be learned by measuring the re-emission rate, because different individuals of the same species of plant can re-emit light at different rates. And the same plant may re-emit light differently at different times of day or under different growth conditions.

Improving plant efficiency

This variation interests Kahn and other scientists at WSU, including his colleagues Helmut Kirchhoff, Asaph Cousins, Michael Neff and Gerry Edwards. Photosynthesis is poorly understood, but we do know that, at most, plants only capture about one percent of the energy available to them.

“Imagine if we could get plants to be more efficient in turning that energy into more plant. We might be able to turn that into higher yields of food, into biofuel or into other valuable products,” Kahn said.

This is new territory, but the WSU scientists are optimistic that their work will pay off.

“A lot of what we do at WSU, including this kind of research focused on basic plant biology and understanding photosynthesis, is trying to grasp how plants do what they do,” Kahn said. “We are trying to stay ahead of the curve and give producers options for the future.

“We’ve got a growing population, a changing climate, a shifting water supply – all of these things mean producers need science at their backs to help them evaluate their options as they go forward,” he said.

“We’ve got to eat! Looked at over centuries, getting enough to eat has rarely been easy,” Kahn said. “And looking forward, it is going to take a lot of innovating to keep up.”