Motor protein significantly regulates adaptation to salt stress through the intracellular Na⁺ homeostasis mechanism

Salt stress is a major factor that impairs plant growth and yield. In a breakthrough, researchers from Waseda University have revealed that Arabidopsis thaliana myosin XI-1—a member of the motor protein myosin XI—significantly regulates adaptation to salt stress via intracellular sodium ion (Na⁺) homeostasis. It can thus serve as a promising molecular target for the development of salt-tolerant crops, contributing to sustainable farming in saline-affected regions.

Soil salinity is a key abiotic stress factor. Salt stress substantially impairs plant growth, development, and productivity, significantly reducing crop yields worldwide. It induces various kinds of stress in plant organs, including toxic ion accumulation, oxidative stress, and osmotic stress. Notably, high sodium ion (Na⁺) levels affect protein synthesis, photosynthetic efficiency, nutrient homeostasis, and enzyme activities, causing long-term damage to plants.

Therefore, it is crucial to investigate the molecular mechanisms underlying salt tolerance. Recently, scientists have implicated myosin XI, a motor protein that primarily facilitates intracellular trafficking and organelle movement in plant cells, in abiotic stress responses. However, its specific role in salt tolerance remains poorly understood.

Recently, researchers from Waseda University—PhD student Haiyang Liu from the Graduate School of Science and Engineering and Professor Motoki Tominaga from the Faculty of Education and Integrated Arts and Sciences, School of Education—have revealed that the expression of three members, AtXI-K, AtXI-2, and AtXI-1, known as the main drivers of cytoplasmic streaming, was altered under salt stress conditions. Among these, they discovered that only the loss-of-function mutant of AtXI-1 exhibited higher salt tolerance compared to the wild-type (WT). Their insightful findings were made available online and have been published in the journal Plant & Cell Physiology on October 27, 2025.

Liu discusses the motivation behind their present research by stating, “This research was driven by the goal of understanding how plants maintain cellular organization under extreme environmental stress. While motor proteins such as myosin XI have been hypothesized to regulate ion balance, this possibility has remained largely unexplored.”

The team found that the triple mutant (3ko), as well as the single atxi-1 mutant, exhibited improved salt tolerance. In contrast, the salt tolerance of atxi-k, atxi-2, and the double mutant (2ko) lines was not significantly different from that of the WT Arabidopsis plants. This observation points to a particular role of AtXI-1 in modulating salt tolerance.

Further investigations revealed that the atxi-1 plants accumulated lower amounts of Na⁺, while maintaining higher levels of chlorophyll and proline under salt stress conditions, in comparison to their WT counterparts. However, 3ko lines exhibited low seed germination under salt stress, indicating a stage-specific tolerance mechanism.

Considering all the above insights, the researchers propose that Arabidopsis myosin XI-1 substantially regulates adaptation to salt stress, likely via the intracellular Na⁺ homeostasis mechanism. These findings suggest functional diversification among myosin XI members and provide valuable insights into myosin XI-mediated stress responses, identifying potential targets for enhancing crop resilience to salinity.

“Our work offers a new strategy for improving crop salt tolerance by targeting myosin XI function. This could enable the development of salt-resilient cultivars suited for saline soils, contributing to sustainable agriculture under climate stress. This research addresses the global challenge of soil salinization, which threatens agricultural productivity and food security. By uncovering a novel role for myosin XI in regulating Na⁺ homeostasis, it offers a molecular target for developing salt-tolerant crops, contributing to sustainable farming in saline-affected regions,” concludes Liu, highlighting the potential real-life applications of their breakthrough study.

By revealing how myosin XI-1 contributes to salt tolerance, this research advances the molecular understanding of plant stress responses and offers a promising direction for developing resilient crops through targeted genetic and physiological studies.

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Reference
Title of original paper: Myosin XI-1 Mediates Salt Tolerance Through a Na⁺ Transport Pathway in Arabidopsis

Journal: Plant & Cell Physiology

DOI: 10.1093/pcp/pcaf140

Authors: Haiyang Liu¹ and Motoki Tominaga²

Affiliations:
¹Graduate School of Science and Engineering, Waseda University, Japan
²Faculty of Education and Integrated Arts and Sciences, Waseda University, Japan

About Waseda University
Located in the heart of Tokyo, Waseda University is a leading private research university that has long been dedicated to academic excellence, innovative research, and civic engagement at both the local and global levels since 1882. The University has produced many changemakers in its history, including eight prime ministers and many leaders in business, science and technology, literature, sports, and film. Waseda has strong collaborations with overseas research institutions and is committed to advancing cutting-edge research and developing leaders who can contribute to the resolution of complex, global social issues. The University has set a target of achieving a zero-carbon campus by 2032, in line with the Sustainable Development Goals (SDGs) adopted by the United Nations in 2015.

To learn more about Waseda University, visit https://www.waseda.jp/top/en

About Haiyang Liu from Waseda University
Haiyang Liu, the first author of this study, is a PhD student at the Graduate School of Science and Engineering at Waseda University, Japan. His research interest lies in the study of myosin XI, a key player in plant drought defense, boron uptake, and salt tolerance. He has authored three papers on these topics with Motoki Tominaga, the corresponding author of this study, a professor at the Faculty of Education and Integrated Arts and Sciences at the School of Education at Waseda University.