To maximize water uptake, plant roots adapt their shape to ensure survival in the driest conditions. Plant roots pause branching when they lose contact with water, and only resume once they reconnect with moisture.
Scientists at the University of Nottingham discovered this novel water sensing mechanism, which they refer to as hydro-signaling. The results of the study show how plant hormone movement is linked with fluctuations in water availability.
Climate change has amplified water stress on plants as rainfall patterns become more erratic, and rain-fed crops have been particularly impacted.
Roots reduce the impact of water stress on plants by adapting their shape to secure more water. Understanding how roots sense water stress is of vital importance to enhance the resilience of crops.
Using X-ray imaging, the researchers found 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 research provides critical information about the key genes and processes controlling root branching in response to limited water availability. These findings could help scientists design approaches to manipulate root architecture and enhance water capture and yield in crops.
“When roots are in contact with moisture, a key hormone signal (auxin) moves inwards with water, triggering new root branches,” explained Dr. Poonam Mehra. “However, when roots lose contact with moisture, they rely on internal water sources that mobilises 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.”
As climate change is already affecting water availability, scientists are currently designing plants that can access water under changing conditions.
Professor Malcolm Bennett concluded: “These new discoveries were only possible because of the cutting-edge tools and collaborative approaches of the authors, which involved an international team of scientists based in the UK, Belgium, Sweden, USA and Israel.”
The research is published in the journal Science.
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