A team of researchers led by scientists from the University of Western Australia (UWA) and the ARC Centre of Excellence in Plant Energy Biology (PEB) has uncovered the mechanism by which crop roots penetrate hard soils, a breakthrough that could lead to new strategies for improving crop yields in drought-prone regions.

The research, published in the journal Nature Plants, reveals how roots of the model plant Arabidopsis thaliana respond to mechanical impedance, such as hard soil, by altering their growth patterns and initiating the production of specialized proteins that help them penetrate the soil.

Using a combination of imaging techniques, genetic analysis, and biophysical assays, the researchers found that when roots encounter hard soil, they switch from their normal, straight growth pattern to a more tortuous one, allowing them to navigate the obstacles in the soil.

Additionally, the roots produce specialized proteins called expansins, which help break down the cell walls and loosen the soil, making it easier for the roots to penetrate.

"Our findings provide a detailed understanding of the mechanisms by which roots respond to mechanical impedance and offer potential targets for genetic manipulation to improve root penetration and anchorage in crops," said Dr. Ryan de Jonge, a PEB research fellow and co-first author of the study.

The research team, including Dr. de Jonge, Professor Peter Ho, Dr. Christopher O'Leary, and Dr. Anna Zourelidou, used a custom-built rhizotron imaging system to visualize root growth and development in real-time.

They observed that when Arabidopsis roots encountered hard soil, they initially stopped growing, but then resumed growth after a few days, albeit at a slower rate and with a different growth pattern.

The researchers also found that the production of expansins was induced by the mechanical impedance of the hard soil, and that these proteins were essential for root penetration.

"This discovery has the potential to transform agriculture in drought-prone regions, where hard soils can severely limit crop yields," said Professor Peter Ho, Director of PEB and co-senior author of the study.

"By understanding the mechanisms by which roots penetrate hard soils, we can now develop strategies to improve root growth and anchorage in crops, which could lead to increased crop yields and improved food security in these regions."

The research team is now working on identifying the key genetic regulators of root penetration and anchorage, with the aim of developing new crop varieties with improved root systems that can better withstand drought and other environmental stresses.