Plant scientists from the University of Nottingham have discovered a novel water sensing mechanism that they have called ‘Hydro-Signaling’, which shows how hormone movement is linked with water fluxes. The findings have been published today in Science.

How roots adapt to water stress

Roots play a critical role in reducing the impact of water stress on plants by adapting their shape (such as branching or growing deeper) to secure more water. Discovering how plant roots sense and adapt to water stress is vital importance for helping ‘future proof’ crops to enhance their climate resilience.

Using X-ray micro-CT imaging researchers were able to reveal that roots alter their shape in response to external moisture availability by linking the movement of water with plant hormone signals that control root branching.

The study provides critical information about the key genes and processes controlling root branching in response to limited water availability, helping scientists design novel approaches to manipulate root architecture to enhance water capture and yield in crops.

Dr. Poonam Mehra, postdoctoral fellow, from the School of Biosciences is one of the lead authors and explains:

“When roots are in contact with moisture, a key hormone signal (auxin) moves inwards with water, triggering new root branches. However, when roots lose contact with moisture, they rely on internal water sources that mobilize another hormone signal (ABA) outwards, which acts to block the inwards movement of the branching signal. This simple, yet elegant mechanism enables plant roots to fine tune their shape to local conditions and optimize foraging.”

In other words, roots adapt their shape, pausing branching when they lose contact with water and resume once they detect moisture again.