AimÉe Classen and Nathan Sanders

UTK ecology and evolutionary biology

When humans get too warm, their internal thermostats bring blood to the skin to release body heat; they perspire, drink water, and move out of the sun to stay cool.

Plants have their own way of responding, says JDRD team leader Aimée Classen. Obviously they can’t go to the tap for a drink, or pick up and move to the shade. But some plants have evolved elaborate genetic mechanisms to combat heat stress.

Classen, co-leader Nathan Sanders, and ORNL plant molecular ecologist David Weston have joined forces on companion JDRD/LDRD projects to compare genetic responses of plants in which the entire genome is known (model organisms) with non-model plants where the genome is not known.

"David is interested in heat shock," Classen says. "He works with gene networks and looks at how plants turn genes on and off to regulate their responses.

"You can measure plant reactions to heat through respiration and photosynthesis. Another way is to look at what the genes are doing."

Weston’s team has been growing two model plants, Arabidopsis (small forage plants) and Populous (trees); Classen, Sanders, and crew are growing Solidago—the weedy plant we know as goldenrod that grows in ditches and across old fields. They will use Solidago species native to Tennessee’s warm summer climate and those accustomed to cooler Connecticut summers.

Goldenrod is an excellent choice for a number of reasons, Classen says; "It has a huge geographic and thermal range—you see it from Mississippi to Canada; we know a lot about it; and it has a gigantic genome."

Ultimately, the two teams want to see whether heat stress causes the

JDRD Project: Developing a systems biology approach for linking genetic and environmental constraints to primary productivity — can patterns scale to the field?;
LDRD Project: Developing a systems biology approach for linking genetic and environmental constraints to primary productivity in model and nonmodel species, David Weston.

same genes to turn on or off in all three plants—a result that would suggest the genes were conserved (retained) through evolutionary time because they carry out vital tasks.

"What gets interesting,” says Classen, “is discovering how much of a plant’s innate ability to deal with temperature comes from genetic flexibility."

Though in its first summer, preliminary work is already proving useful in grant proposals and has sparked several side projects for undergraduate research.