Understanding how organisms work together

David Weston has been drawn to the natural world since he was a child exploring a small forest near his home.

Turning that fascination into a science career, he has examined topics such as plant genomics and the relationship between plants and the organisms in their environment. Weston has bachelor’s and master’s degrees in plant biology from Cornell University and a Ph.D. in biology from Clemson University. He worked at ORNL as a postdoc before joining the lab’s research staff in 2009.

Weston won a 2017 Early Career Research Program award from DOE’s Office of Science for his proposal “Determining the Genetic and Environmental Factors Underlying Mutualism Within a Plant–Microbiome System Driving Nutrient Acquisition and Exchange.” We talked with him about the project and about what drew him to a career in science. This is an edited transcript.

What will you be studying in this project?

I’ll be studying, at a very fundamental level, symbiosis, the question of how two organisms with very different physiologies—very different genetic backgrounds—interact in a way in which both benefit.

The system we’re using is a small plant. It’s called sphagnum peat moss. The living part is only a few centimeters high. It doesn’t even have any roots. But yet it has a lot of open cells that allow bacteria to colonize, and these bacteria colonize often in a symbiotic fashion, meaning they’ll take nitrogen from the atmosphere and provide it to the plant. In return, the plant provides sugars back to these bacteria, and together they seem to grow in a beneficial manner.

How do you plan to conduct this research?

The research is going to take place in two separate areas. In the first area we’re going to use a system called synthetic communities. Here we have created a population of moss plants that all have their genomes sequenced.

So we have a bunch of plants that are different genetically. We also have a bunch of microbes and nitrogen-fixing bacteria that are very different. And then we’re going to put these plants and microbes together. In these synthetic communities we’re going to ask questions regarding what the underlying genetic and environmental basis is for these organisms to operate together. But I think just as importantly, we’re interested in how you can change this so that the organisms break apart. Are there certain combinations that are harder to break apart than others? If so, why?

What we hope to get from that synthetic community are these rules or principles by which the symbiosis operates. And then we want to see if we can observe those rules, or the behavior of those rules, under natural field settings. So we have field sites that we will be investigating, as well.

Why is this work important?

I’m lucky. I’m working in a system which has impact at an ecosystem, landscape and even global scale. This is nice, because as a scientist you can really get into the weeds of discovery and forget about what the real implications of your research are. Just finding something new is interesting, but in this case we have impact.

In particular, the moss we’re looking at and the microbes that we’re investigating reside in peat bogs or peatlands. And peat bogs in particular are only about 3 percent of the entire global land area, but they contain upwards of 25 percent of all the stored soil carbon. In these particular ecosystems, what happens is this plant material dies, and it goes into the ecosystem, where it stays in a recalcitrant form for many thousands of years. So it tends to create a large carbon sink.

Because sphagnum peat mosses are dominant members in many peat bog ecosystems, how they operate really dictates in large part how these ecosystems function. The idea is if these parts decline, it may change how these ecosystems function. What we worry about, of course, is that these large carbon sinks may eventually become a carbon source to the atmosphere.

What attracted you to a career in science?

That path has taken a couple of routes. From a really early age, I took to natural history. Being out in nature was always a great thing. And then, like many Americans, I had family members, especially a grandmother and aunt, who had a strong tie to gardening.

So on one hand I had this tie to nature from a natural sense as well as from an agricultural sense, but then on the other hand, I went to college during the time of the Human Genome Project, and there you’re unlocking the discovery of biology through the genetic code of an organism.

Really what I ended up doing was putting these two systems together. So a lot of what I do is considered ecological genetics, or genomics, where we’re tying these two disciplines together.