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Uzilday B, Takahashi K, Kobayashi A, Uzilday RO, Fujii N, Takahashi H, Turkan I. Role of Abscisic Acid, Reactive Oxygen Species, and Ca 2+ Signaling in Hydrotropism-Drought Avoidance-Associated Response of Roots. PLANTS (BASEL, SWITZERLAND) 2024; 13:1220. [PMID: 38732435 PMCID: PMC11085316 DOI: 10.3390/plants13091220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 04/23/2024] [Accepted: 04/24/2024] [Indexed: 05/13/2024]
Abstract
Plant roots exert hydrotropism in response to moisture gradients to avoid drought stress. The regulatory mechanism underlying hydrotropism involves novel regulators such as MIZ1 and GNOM/MIZ2 as well as abscisic acid (ABA), reactive oxygen species (ROS), and Ca2+ signaling. ABA, ROS, and Ca2+ signaling are also involved in plant responses to drought stress. Although the mechanism of moisture gradient perception remains largely unknown, the sensory apparatus has been reported to reside in the root elongation zone rather than in the root cap. In Arabidopsis roots, hydrotropism is mediated by the action of MIZ1 and ABA in the cortex of the elongation zone, the accumulation of ROS at the root curvature, and the variation in the cytosolic Ca2+ concentration in the entire root tip including the root cap and stele of the elongation zone. Moreover, root exposure to moisture gradients has been proposed to cause asymmetric ABA distribution or Ca2+ signaling, leading to the induction of the hydrotropic response. A comprehensive and detailed analysis of hydrotropism regulators and their signaling network in relation to the tissues required for their function is apparently crucial for understanding the mechanisms unique to root hydrotropism. Here, referring to studies on plant responses to drought stress, we summarize the recent findings relating to the role of ABA, ROS, and Ca2+ signaling in hydrotropism, discuss their functional sites and plausible networks, and raise some questions that need to be answered in future studies.
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Affiliation(s)
- Baris Uzilday
- Department of Biology, Faculty of Science, Ege University, Bornova 35100, Izmir, Turkey
| | - Kaori Takahashi
- Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan
| | - Akie Kobayashi
- Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan
| | - Rengin Ozgur Uzilday
- Department of Biology, Faculty of Science, Ege University, Bornova 35100, Izmir, Turkey
| | - Nobuharu Fujii
- Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan
| | - Hideyuki Takahashi
- Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan
- Research Center for Space Agriculture and Horticulture, Graduate School of Horticulture, Chiba University, Matsudo, Chiba 271-8510, Japan
| | - Ismail Turkan
- Department of Biology, Faculty of Science, Ege University, Bornova 35100, Izmir, Turkey
- Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan
- Faculty of Agricultural Sciences and Technologies, Yasar University, University Street, No. 37-39, Bornova 35100, Izmir, Turkey
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Vahldick H. Don't be MIZguided, know where to grow! Commun Biol 2024; 7:73. [PMID: 38195918 PMCID: PMC10776833 DOI: 10.1038/s42003-023-05707-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2024] Open
Affiliation(s)
- Hannah Vahldick
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052, Ghent, Belgium.
- VIB Center for Plant Systems Biology, Technologiepark 71, 9052, Ghent, Belgium.
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Akita K, Miyazawa Y. Auxin biosynthesis, transport, and response directly attenuate hydrotropism in the latter stages to fine-tune root growth direction in Arabidopsis. PHYSIOLOGIA PLANTARUM 2023; 175:e14051. [PMID: 37882259 DOI: 10.1111/ppl.14051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/28/2023] [Accepted: 10/05/2023] [Indexed: 10/27/2023]
Abstract
Roots detect water potential gradients in the soil and orient toward moister areas, a response known as hydrotropism that aids drought avoidance. Although auxin is crucial in tropism, its polar transport is not essential for hydrotropism in Arabidopsis. Moreover, antiauxin treatments in Arabidopsis produced inconsistent outcomes: some studies indicated auxin action was necessary while others did not. In this study, we examined auxin's physiological role in hydrotropism. We found that inhibiting auxin biosynthesis or transport intensified hydrotropic bending not only in wild-type, but also in hydrotropism defective mutants, namely miz1-1 and miz2 plants. Given that miz1-1 and miz2 exhibited compromised hydrotropism even under clinorotated conditions, we infer that auxin biosynthesis and transport directly suppress hydrotropism. Additionally, tir1-10, afb1-3, and afb2-3 displayed augmented hydrotropism. We observed a significant delay in hydrotropic bending in arf7-1arf19-1, suggesting that ARF7 and ARF19 amplify hydrotropism in its early stages. To discern the functional ties of ARF7/19 with MIZ1 and MIZ2, we studied the hydrotropic phenotypes of arf7-1arf19-1miz1-1 and arf7-1arf19-1miz2. Both triple mutants had diminished early-stage hydrotropism yet showed partial but significant recovery in the later stages. Given MIZ1's role in reducing auxin levels and MIZ2's essentiality for MIZ1 functionality, we conclude that auxin inhibits hydrotropism downstream of MIZ1 in later stages to refine root bending. Furthermore, it is posited that gene expression driven by ARF7 and ARF19 is pivotal for early-stage root hydrotropism.
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Affiliation(s)
- Kotaro Akita
- Graduate School of Science and Engineering, Yamagata University, Yamagata, Japan
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