Helical Buckling Allows Plant Roots to Pierce Soil (Video)

Scientists have observed how some plant roots navigate their way through difficult environments with implications for producing crops that can cope with climate change and tough soil conditions.

A team of U.S. researchers studied the root behavior of the small legume Medicago truncatula in layered transparent gel using 3D time-lapse imaging. The top layer was soft and allowed the roots to grow straight down. However, when they reached the thick lower layer, the roots started to coil up like springs.

“When the roots hit the stiff barrier, growth causes them to buckle like a wire or rod that’s been compressed,” said study lead researcher Jesse Silverberg at Cornell University in a press release.

“But by twisting, the buckled roots become helical, allowing the root to push off more gel and get more force at the tip.”

The team learned that plant roots can alter their growth to generate more force for penetrating harder substrates. Interestingly, 74 percent of the roots studied twisted in a counter-clockwise direction.

“Suppose the plant is growing along and finds itself stuck at a layer of clay or tough clump of soil,” Silverberg said. “The root needs an extra force to push through these barriers, and the mathematical model tells us how large of a helix the root needs to grow to do just that.”

“Roughly, the stiffer the barrier, the larger the helix,” said Silverberg.

The study was published online in the Early Edition of Proceedings of the National Academy of Sciences on Sept. 24.

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