How plants sense touch, gravity and other physical forces

From Physorg.com:

At the bottom of plants' ability to sense touch, gravity or a nearby trellis are mechanosensitive channels, pores through the cells' plasma membrane that are opened and closed by the deformation of the membrane. Elisabeth Haswell, Ph.D., a biologist at Washington University in St. Louis, is studying the roles these channels play in Arabdopsis plants by growing mutant plants that lack one or more of the 10 possible channel proteins in this species.

"Picture yourself hiking through the woods or walking across a lawn," says Elizabeth Haswell, PhD, assistant professor of biology in Arts & Sciences at Washington University in St. Louis. "Now ask yourself: Do the bushes know that someone is brushing past them? Does the grass know that it is being crushed underfoot? Of course, plants don't think thoughts, but they do respond to being touched in a number of ways."

"It's clear," Haswell says, "that plants can respond to physical stimuli, such as gravity or touch. Roots grow down, a 'sensitive plant' folds its leaves, and a vine twines around a trellis. But we're just beginning to find out how they do it," she says.

More here.