The Secret Motor Protein That Saves Crops from Drought: Uncovering Myosin XI’s Role in Plant Stress Response

In a world where climate change is intensifying, drought has become a major threat to global agriculture. To survive such adverse events, plants have evolved remarkable strategies to conserve water and ensure their survival. One such strategy is “stomatal closure,” where the tiny pores on leaf surfaces, called stomata, close to limit water loss.

While the role of plant hormones like abscisic acid (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. This study, led by Professor Motoki Tominaga from Waseda University, Japan, aimed to determine whether myosin XI actively contributes to drought response in plants and to uncover the processes involved.

The researchers used Arabidopsis thaliana as a model plant to investigate the role of myosin XI in drought response. They created genetically modified plants lacking one, two (2ko), or all three (3ko) major myosin XI genes and compared them to wild-type plants across several tests, including drought survival assays, water loss measurements, stomatal aperture analysis, and ABA sensitivity.

The results were striking. Plants lacking myosin XI, especially the 2ko and 3ko mutants, showed a higher rate of water loss, impaired stomatal closure, and lower survival under drought. They were also less responsive to ABA, as seen in higher germination rates and reduced inhibition of root growth under hormone treatment.

At the cellular level, these mutants exhibited reduced reactive oxygen species (ROS) production and disrupted microtubule remodeling, both essential for ABA-induced stomatal closure. Key stress-related genes also showed decreased expression, indicating that myosin XI plays a regulatory role in ABA signaling.

This study reveals that myosin XI is not just a transport protein but actively supports plant drought defense by coordinating ROS signaling, microtubule remodeling, and gene activation in guard cells. This enables plants to close stomata more effectively and conserve water.

The findings of this research offer several important breakthroughs and pave the way for new research directions. They reveal a previously unrecognized role of myosin XI in plant abiotic stress response, offering deeper insight into how intracellular transport systems aid environmental adaptation.

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. The researchers aim to further advance their research so that this knowledge can be applied to agricultural technologies that support farming in the face of climate change.

In summary, this study uncovers myosin XI as a critical player in plant drought response, linking cellular transport machinery to hormone signaling. As climate pressures grow, insights like these offer promising paths toward developing resilient, water-efficient crops for a changing world.

The Fiji ant plant, Squamellaria, has long been studied for its remarkable ability to form symbiotic relationships with ants. But what makes this relationship truly unique is the way the plant provides separate “condos” for each ant species, preventing conflicts that could arise from competition for resources. Researchers from Washington University in St. Louis and Durham University in the United Kingdom have made a groundbreaking discovery about the secrets behind this harmonious coexistence.

The study, published in Science, reveals that compartmentalization is the key to mitigating conflicts between unrelated symbionts. By creating separate chambers within its tubers, Squamellaria prevents ant colonies from coming into contact with each other, thereby reducing competition for resources and eliminating deadly conflicts.

“We were able to visualize directly what theory has long predicted – that unrelated partners would conflict by competing for host resources,” said Susanne S. Renner, senior author of the study. “But here we also have a simple, highly effective evolutionary strategy to mitigate these conflicts: compartmentalization.”

The researchers used computed-tomography scanning and 3D modeling to visualize the tubers’ internal structure and understand how the plant enables multiple ant species to live together in harmony. They found that removing the partition walls between the chambers resulted in immediate conflict and high worker mortality, emphasizing the importance of compartmentalization.

This discovery has significant implications for our understanding of symbiotic relationships and the ecology and evolution of species interactions. It highlights the remarkable ability of Squamellaria to adapt to its environment and form mutually beneficial relationships with ants, even when faced with conflicting interests.

The study’s findings also shed light on a long-standing problem in ecological theory – how unrelated partners can form long-term mutualistic relationships despite competing for host resources. By providing separate compartments, Squamellaria has evolved an effective solution to this problem, allowing multiple ant species to coexist peacefully and benefiting from each other’s presence.

In conclusion, the tiny condos of Fiji’s ant plant have unlocked a secret to harmonious coexistence among unrelated symbionts, offering new insights into the complex relationships between species.

The future of sustained space habitation relies heavily on our ability to grow fresh food away from Earth. The Moon-Rice project is a groundbreaking initiative that uses cutting-edge experimental biology to create an ideal future food crop for deep-space outposts and extreme environments back on Earth.

Resupplying food from Earth has been the norm in modern space exploration, but this often comes with pre-prepared meals that rarely contain fresh ingredients. To combat the negative effects of space travel on human health, a reliable source of food rich in vitamins, antioxidants, and fibers is crucial.

The Moon-Rice project aims to develop the perfect crop for sustaining life in space for long-duration missions, such as permanent bases on the Moon or Mars. Dr. Marta Del Bianco, a plant biologist at the Italian Space Agency, explains that one of the major challenges is the current size of crops grown on Earth, even dwarf varieties being too large to be grown reliably in space.

To address this issue, researchers are isolating mutant rice varieties that can grow to just 10 cm high, maximizing production and growth efficiency by altering plant architecture. Additionally, since meat production will be too inefficient for resource- and space-limited space habitats, Dr. Del Bianco’s team is exploring ways to enrich the protein content of the rice.

The Moon-Rice project is not a solo effort but rather a collaborative initiative between three Italian Universities: the University of Milan, Rome ‘Sapienza’, and Naples ‘Federico II’. This four-year project has already shown promising preliminary results.

Dr. Del Bianco’s personal focus is on how the rice plants will cope with micro-gravity. She simulates micro-gravity conditions on Earth by continually rotating the plant so that it doesn’t know where the up and down is. This is the best they can do on Earth, as doing experiments in real microgravity conditions in space is complex and expensive.

Not only can fresh food be more nutritious than pre-cooked and packaged space meals, but it also has significant psychological benefits too. Watching and guiding plants to grow is good for humans, and while pre-cooked or mushy food can be fine for a short period of time, it could become a concern for longer-duration missions.

Space exploration requires astronauts to be in peak physical and psychological condition. If we can make an environment that physically and mentally nourishes the astronauts, it will reduce stress and lower the chances of people making mistakes. In space, the best-case scenario of a mistake is wasted money, and the worst-case scenario is the loss of lives.

The Moon-Rice project has applications beyond space exploration, too. If we can develop a robust crop for space, it could be used at the Arctic and Antarctic poles, or in deserts, or places with only a small amount of indoor space available.

This research will be presented at the Society for Experimental Biology Annual Conference in Antwerp, Belgium on July 9th, 2025.