New time-lapse videos capture something that’s too slow for our eyes to see: the growing tips of plant roots make corkscrew-like motions, waggling and winding in a helical path as they burrow into the soil. By using time-lapse footage, along with a root-like robot to test ideas, researchers have gained new insights into how and why rice root tips twirl as they grow.

When they played their footage back at 15 frames per second, compressing 100 hours of growth into less than a minute, they saw that rice roots use a trick to gain their first foothold in the soil: their growing tips make corkscrew-like motions, waggling and winding in a helical path.

By using their time-lapse footage, along with a root-like robot to test ideas, the researchers gained new insights into how and why plant root tips twirl as they grow.

The first clue came from something else the team noticed: some roots can’t do the corkscrew dance. The culprit, they found, is a mutation in a gene called HK1 that makes them grow straight down, instead of circling and meandering like other roots do.

The team also noted that the mutant roots grew twice as deep as normal ones. Which raised a question: «What does the more typical spiraling tip growth do for the plant?» said Isaiah Taylor, a postdoctoral associate in Benfey’s lab at Duke.

Winding movements in plants were «a phenomenon that fascinated Charles Darwin,» even 150 years ago, Benfey said. In the case of shoots, there’s an obvious utility: twining and circling makes it easier to get a grip as they climb towards the sunlight. But how and why it happens in roots was more of a mystery.

Story Source:
Materials provided by Duke University. Original written by Robin A. Smith. Note: Content may be edited for style and length.