Foraging for water by MIZ1-mediated antagonism between root gravitropism and hydrotropism
Zhang Y, Bao Z, Smoljan A, Liu Y, Wang H, Friml J. 2025. Foraging for water by MIZ1-mediated antagonism between root gravitropism and hydrotropism. Proceedings of the National Academy of Sciences of the United States of America. 122(20), e2427315122.
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Abstract
Root system integrates multiple environmental cues, chiefly gravity and soil humidity, to anchor plants in soil and forage for water. While the mechanism of auxin-mediated root gravitropism is comparably well-understood, the root’s capability to grow toward moist soil for water uptake and drought avoidance, termed root hydrotropism, remains largely mysterious. Here, we provide key insights into the mechanism of hydrotropic growth and assign a role to the master regulator of hydrotropism, MIZU-KUSSEI 1 (MIZ1). We show that efficient hydrotropism requires the attenuation of antagonistically acting gravitropism, which is inhibited under drought conditions. Drought stress interferes with subcellular trafficking and the lateral mobility of PIN auxin transporters, which are polarly localized at the root cell plasma membranes. This leads to defects in PIN2 polarity and gravity-induced polarization of PIN3, ultimately inhibiting gravity-induced auxin redistribution and root bending. The miz1 mutant is defective in all these regulations, and in support of MIZ1’s action on PINs, pin mutations rescue the hydrotropic defects in the miz1 mutant. These observations identify a mechanism for how drought via MIZ1 attenuates gravitropism to promote root hydrotropism for efficient water foraging under drought conditions.
Publishing Year
Date Published
2025-05-20
Journal Title
Proceedings of the National Academy of Sciences of the United States of America
Publisher
National Academy of Sciences
Acknowledgement
This work was supported by the European Union’s Horizon 2020 research and innovation Programme (European Research Council grant agreement number 742985), Austrian Science Fund (FWF, grant number I 3630-B25), (Institute of Science and Technology Austria) Fellow program, the Qin Chuangyuan High-level Innovation and Entrepreneurship Talent Program (QCYRCXM-2022-237), the Fundamental Research Funds for Northwest A&F University and partly supported by the open funds of the State Key Laboratory of Plant Environmental Resilience (SKLPERKF2416). We also thank the Teaching and Research Core Facility at the College of Life Sciences, Northwest A&F University, particularly Dr. Ningjuan Fan for technical assistance.
Volume
122
Issue
20
Article Number
e2427315122
eISSN
IST-REx-ID
Cite this
Zhang Y, Bao Z, Smoljan A, Liu Y, Wang H, Friml J. Foraging for water by MIZ1-mediated antagonism between root gravitropism and hydrotropism. Proceedings of the National Academy of Sciences of the United States of America. 2025;122(20). doi:10.1073/pnas.2427315122
Zhang, Y., Bao, Z., Smoljan, A., Liu, Y., Wang, H., & Friml, J. (2025). Foraging for water by MIZ1-mediated antagonism between root gravitropism and hydrotropism. Proceedings of the National Academy of Sciences of the United States of America. National Academy of Sciences. https://doi.org/10.1073/pnas.2427315122
Zhang, Yuzhou, Zhulatai Bao, Adrijana Smoljan, Yifan Liu, Huihui Wang, and Jiří Friml. “Foraging for Water by MIZ1-Mediated Antagonism between Root Gravitropism and Hydrotropism.” Proceedings of the National Academy of Sciences of the United States of America. National Academy of Sciences, 2025. https://doi.org/10.1073/pnas.2427315122.
Y. Zhang, Z. Bao, A. Smoljan, Y. Liu, H. Wang, and J. Friml, “Foraging for water by MIZ1-mediated antagonism between root gravitropism and hydrotropism,” Proceedings of the National Academy of Sciences of the United States of America, vol. 122, no. 20. National Academy of Sciences, 2025.
Zhang Y, Bao Z, Smoljan A, Liu Y, Wang H, Friml J. 2025. Foraging for water by MIZ1-mediated antagonism between root gravitropism and hydrotropism. Proceedings of the National Academy of Sciences of the United States of America. 122(20), e2427315122.
Zhang, Yuzhou, et al. “Foraging for Water by MIZ1-Mediated Antagonism between Root Gravitropism and Hydrotropism.” Proceedings of the National Academy of Sciences of the United States of America, vol. 122, no. 20, e2427315122, National Academy of Sciences, 2025, doi:10.1073/pnas.2427315122.
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