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With the improvement of genetic analysis tools over the past decade, researchers are now experimenting with techniques to examine how plants respond to climate change conditions at a molecular level. ORNL researcher Stan Wullschleger and postdoctoral researcher David Weston have set up an experiment with Arabidopsis, one of three plants whose genomes have been sequenced, to see how the plants respond genetically to higher levels of CO₂.

"I tend to think of our experimental work at ORNL as the tale of two scales—genes and ecology," Wullschleger says. "This project offers small-scale insights into big-time problems."

The experiment employs two types of Arabidopsis plants, one with a complete complement of genes as a control and the other with a single gene deleted to influence the uptake and assimilation of nitrogen by the plant. By comparing the two types—grown in monocultures and in mixtures—Wullschleger says researchers can ask unique questions about how genes potentially control the function of plants, populations and ecosystems along with "the goods and services they provide to society." He adds, "We are studying ecological properties and processes at the level of the gene. We think there is value in looking at some of these ecological questions at that very basic, fundamental scale."

Wullschleger and Weston use systems biology, physiology, biochemistry and ecosystem measurements to characterize how the plants interact from one generation to the next, to track the relative abundance of the two different types from one generation to the next and to understand how gene-level changes translate to populations and ecosystem processes. Early results show that altering the expression of a single gene impacts carbon and nitrogen metabolism, which, in turn, leads to delayed flowering and reduced seed production. These effects translate to rapid shifts in plant composition and probable impacts on nutrient cycles. Three generations of plants have been grown in the mesocosms located in the ORNL green-houses. The researchers hope to complete 10 to 15 generations of growth in the coming years.

The project's most exciting potential, says Weston, is that the systems biology approach will unearth a storehouse of information that could affect models and even mitigation responses to global climate change. "The genome is an integrated history of the organism, representing the evolutionary response to selection pressures that have happened from the time that these land plants actually began," he says. "If we can unlock that potential and see the genomic code behind adaptive mechanisms to past climates, we will have the potential to use that information to predict plants' behavior in future climates."—Larisa Brass

Contact: Stan D. Wullschleger

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