A better understanding of how plants survive drought could help grow more sustainable crops, say scientists in Japan, who have identified the hidden role played by a plant hormone.

With climate change exacerbating drought conditions, the researchers at Waseda University in Tokyo have identified a hidden player in plant survival - myosin XI, a motor protein traditionally known for transporting cellular components. This unexpected link between the motor protein and hormone signalling that regulates water loss deepens our understanding of plant stress responses.

It also opens a promising avenue for engineering drought-resilient crops. Targeting myosin XI could enhance water-use efficiency and help reshape the future of agriculture in an increasingly arid world.

Drought has become a major threat to global agriculture, impacting crop yields and food security. To survive such adverse events, plants have evolved several strategies.

One such strategy to counteract water scarcity is stomatal closure, where the tiny pores on a leaf's surface, which are responsible for gaseous exchange, close to limit water loss. This process is regulated by the plant hormone abscisic acid (ABA), which plays a crucial role in plants' internal stress-response mechanisms.

While the role of ABA in drought response is well-established, researchers have now identified a surprising contributor to this process: myosin XI, a motor protein traditionally known for transporting cellular components. To explore this, a team of researchers led by Professor Motoki Tominaga from Waseda University, conducted a study to determine whether myosin XI actively contributes to drought response in plants and to uncover the processes involved.

“Although previous studies have suggested a potential involvement of myosin XI in drought stress responses, the underlying mechanisms have remained unclear,” says Tominaga, whose findings were published in Plant Cell Reports.

Researchers used genetically modified thale cress (Arabidopsis thaliana) as a model to investigate the role of myosin XI in drought response. These were then compared to wild-type plants across several tests, including drought survival assays, water loss measurements, stomatal aperture analysis and ABA sensitivity.

The findings revealed that myosin XI actively supports plant drought defence, enabling plants to close stomata more effectively and conserve water.

“It was found that in multiple mutants of plant myosin XI, the rate of water loss during drought is four times faster than in the wild type,” notes Tominaga. “This finding offers a new perspective on how plants adapt to environmental changes.

He added, “This discovery is expected to advance fundamental research on how plants respond to stress and contribute to the development of technologies that improve water-use efficiency in crops grown in drought-prone regions. We aim to further advance our research so that this knowledge can be applied to agricultural technologies that support farming in the face of climate change.”

As climate pressures intensify, insights like these offer promising paths toward developing resilient, water-efficient crops for a changing world, the scientists conclude.