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Retzer K, Weckwerth W. Recent insights into metabolic and signalling events of directional root growth regulation and its implications for sustainable crop production systems. FRONTIERS IN PLANT SCIENCE 2023; 14:1154088. [PMID: 37008498 PMCID: PMC10060999 DOI: 10.3389/fpls.2023.1154088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
Roots are sensors evolved to simultaneously respond to manifold signals, which allow the plant to survive. Root growth responses, including the modulation of directional root growth, were shown to be differently regulated when the root is exposed to a combination of exogenous stimuli compared to an individual stress trigger. Several studies pointed especially to the impact of the negative phototropic response of roots, which interferes with the adaptation of directional root growth upon additional gravitropic, halotropic or mechanical triggers. This review will provide a general overview of known cellular, molecular and signalling mechanisms involved in directional root growth regulation upon exogenous stimuli. Furthermore, we summarise recent experimental approaches to dissect which root growth responses are regulated upon which individual trigger. Finally, we provide a general overview of how to implement the knowledge gained to improve plant breeding.
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Affiliation(s)
- Katarzyna Retzer
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czechia
| | - Wolfram Weckwerth
- Department of Functional and Evolutionary Ecology, Faculty of Life Sciences, Molecular Systems Biology (MoSys), University of Vienna, Wien, Austria
- Vienna Metabolomics Center (VIME), University of Vienna, Wien, Austria
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Stafen CF, Kleine-Vehn J, Maraschin FDS. Signaling events for photomorphogenic root development. TRENDS IN PLANT SCIENCE 2022; 27:1266-1282. [PMID: 36057533 DOI: 10.1016/j.tplants.2022.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 07/26/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Abstract
A germinating seedling incorporates environmental signals such as light into developmental outputs. Light is not only a source of energy, but also a central coordinative signal in plants. Traditionally, most research focuses on aboveground organs' response to light; therefore, our understanding of photomorphogenesis in roots is relatively scarce. However, root development underground is highly responsive to light signals from the shoot and understanding these signaling mechanisms will give a better insight into early seedling development. Here, we review the central light signaling hubs and their role in root growth promotion of Arabidopsis thaliana seedlings.
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Affiliation(s)
- Cássia Fernanda Stafen
- PPGBM - Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS, Brazil
| | - Jürgen Kleine-Vehn
- Institute of Biology II, Chair of Molecular Plant Physiology (MoPP), University of Freiburg, Freiburg, Germany; Center for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, 79104 Freiburg, Germany
| | - Felipe Dos Santos Maraschin
- PPGBM - Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS, Brazil; Departamento de Botânica, Universidade Federal do Rio Grande do Sul - UFRGS, Porto Alegre, RS, Brazil.
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Villacampa A, Fañanás‐Pueyo I, Medina FJ, Ciska M. Root growth direction in simulated microgravity is modulated by a light avoidance mechanism mediated by flavonols. PHYSIOLOGIA PLANTARUM 2022; 174:e13722. [PMID: 35606933 PMCID: PMC9327515 DOI: 10.1111/ppl.13722] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/11/2022] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
In a microgravity environment, without any gravitropic signal, plants are not able to define and establish a longitudinal growth axis. Consequently, absorption of water and nutrients by the root and exposure of leaves to sunlight for efficient photosynthesis is hindered. In these conditions, other external cues can be explored to guide the direction of organ growth. Providing a unilateral light source can guide the shoot growth, but prolonged root exposure to light causes a stress response, affecting growth and development, and also affecting the response to other environmental factors. Here, we have investigated how the protection of the root from light exposure, while the shoot is illuminated, influences the direction of root growth in microgravity. We report that the light avoidance mechanism existing in roots guides their growth towards diminishing light and helps establish the proper longitudinal seedling axis in simulated microgravity conditions. This process is regulated by flavonols, as shown in the flavonoid-accumulating mutant transparent testa 3, which shows an increased correction of the root growth direction in microgravity, when the seedling is grown with the root protected from light. This finding may improve the efficiency of water and nutrient sourcing and photosynthesis under microgravity conditions, as they exist in space, contributing to better plant fitness and biomass production in space farming enterprises, necessary for space exploration by humans.
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Affiliation(s)
- Alicia Villacampa
- Centro de Investigaciones Biológicas Margarita Salas – CSICMadridSpain
| | | | - F. Javier Medina
- Centro de Investigaciones Biológicas Margarita Salas – CSICMadridSpain
| | - Malgorzata Ciska
- Centro de Investigaciones Biológicas Margarita Salas – CSICMadridSpain
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Serine Hydroxymethyltransferase 1 Is Essential for Primary-Root Growth at Low-Sucrose Conditions. Int J Mol Sci 2022; 23:ijms23094540. [PMID: 35562931 PMCID: PMC9100158 DOI: 10.3390/ijms23094540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/18/2022] [Accepted: 04/18/2022] [Indexed: 11/23/2022] Open
Abstract
Plant roots are essential organs for absorbing nutrients from the soil or medium. Sucrose functions as a vital carbon source in root development, and sucrose starvation interferes with the redox state of plant cells. However, the mechanism of root growth at sucrose starvation remains unclear. Here, we report that SHMT1 (serine hydroxymethyltransferase 1) plays a crucial role in primary-root growth. SHMT1 mutation caused decreased sugar levels, excessive H2O2 accumulation, and severe root-growth arrest at sucrose-free conditions, whereas plants with SHMT1 overexpression had increased sugar and decreased H2O2 levels, and longer primary roots. Sucrose supply fully restored root growth of shm1-2, but CO2 alone could not, and SHMT1 is much more stable in roots than shoots at sucrose conditions, suggesting that SHMT1 accumulation in roots is critical for sucrose accumulation and root growth. Further ROS scavenging by GSH application or ROS synthesis inhibition by apocynin application or RBOHD mutation reduced H2O2 levels and partially restored the root-growth arrest phenotype of shm1-2 at low-sucrose conditions, suggesting that SHMT1 modulates root growth via sucrose-mediated ROS accumulation. Our findings demonstrated the role of SHMT1 in primary-root growth by regulating sucrose accumulation and ROS homeostasis in roots.
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García-González J, Lacek J, Weckwerth W, Retzer K. Throttling Growth Speed: Evaluation of aux1-7 Root Growth Profile by Combining D-Root system and Root Penetration Assay. PLANTS 2022; 11:plants11050650. [PMID: 35270119 PMCID: PMC8912881 DOI: 10.3390/plants11050650] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 01/16/2023]
Abstract
Directional root growth control is crucial for plant fitness. The degree of root growth deviation depends on several factors, whereby exogenous growth conditions have a profound impact. The perception of mechanical impedance by wild-type roots results in the modulation of root growth traits, and it is known that gravitropic stimulus influences distinct root movement patterns in concert with mechanoadaptation. Mutants with reduced shootward auxin transport are described as being numb towards mechanostimulus and gravistimulus, whereby different growth conditions on agar-supplemented medium have a profound effect on how much directional root growth and root movement patterns differ between wild types and mutants. To reduce the impact of unilateral mechanostimulus on roots grown along agar-supplemented medium, we compared the root movement of Col-0 and auxin resistant 1-7 in a root penetration assay to test how both lines adjust the growth patterns of evenly mechanostimulated roots. We combined the assay with the D-root system to reduce light-induced growth deviation. Moreover, the impact of sucrose supplementation in the growth medium was investigated because exogenous sugar enhances root growth deviation in the vertical direction. Overall, we observed a more regular growth pattern for Col-0 but evaluated a higher level of skewing of aux1-7 compared to the wild type than known from published data. Finally, the tracking of the growth rate of the gravistimulated roots revealed that Col-0 has a throttling elongation rate during the bending process, but aux1-7 does not.
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Affiliation(s)
- Judith García-González
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.G.-G.); (J.L.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Jozef Lacek
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.G.-G.); (J.L.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Wolfram Weckwerth
- Department of Functional and Evolutionary Ecology, Molecular Systems Biology (MoSys), Faculty of Life Sciences, University of Vienna, Djerassiplatz 1, 1030 Wien, Austria;
- Vienna Metabolomics Center (VIME), University of Vienna, Djerassiplatz 1, 1030 Wien, Austria
| | - Katarzyna Retzer
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.G.-G.); (J.L.)
- Correspondence:
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Lacek J, García-González J, Weckwerth W, Retzer K. Lessons Learned from the Studies of Roots Shaded from Direct Root Illumination. Int J Mol Sci 2021; 22:12784. [PMID: 34884591 PMCID: PMC8657594 DOI: 10.3390/ijms222312784] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 11/16/2022] Open
Abstract
The root is the below-ground organ of a plant, and it has evolved multiple signaling pathways that allow adaptation of architecture, growth rate, and direction to an ever-changing environment. Roots grow along the gravitropic vector towards beneficial areas in the soil to provide the plant with proper nutrients to ensure its survival and productivity. In addition, roots have developed escape mechanisms to avoid adverse environments, which include direct illumination. Standard laboratory growth conditions for basic research of plant development and stress adaptation include growing seedlings in Petri dishes on medium with roots exposed to light. Several studies have shown that direct illumination of roots alters their morphology, cellular and biochemical responses, which results in reduced nutrient uptake and adaptability upon additive stress stimuli. In this review, we summarize recent methods that allow the study of shaded roots under controlled laboratory conditions and discuss the observed changes in the results depending on the root illumination status.
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Affiliation(s)
- Jozef Lacek
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.L.); (J.G.-G.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Judith García-González
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.L.); (J.G.-G.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 128 00 Prague, Czech Republic
| | - Wolfram Weckwerth
- Department of Functional and Evolutionary Ecology, Molecular Systems Biology (MoSys), Faculty of Life Sciences, University of Vienna, Djerassiplatz 1, 1030 Wien, Austria;
- Vienna Metabolomics Center (VIME), University of Vienna, Djerassiplatz 1, 1030 Wien, Austria
| | - Katarzyna Retzer
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, Czech Academy of Sciences, 165 02 Prague, Czech Republic; (J.L.); (J.G.-G.)
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