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Bùi TX, Shekhar V, Marc-Martin S, Bellande K, Vermeer JEM. A tightly regulated auxin signaling landscape is required for spatial accommodation of lateral roots in Arabidopsis. PHYSIOLOGIA PLANTARUM 2025; 177:e70184. [PMID: 40133999 DOI: 10.1111/ppl.70184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2024] [Revised: 02/28/2025] [Accepted: 03/05/2025] [Indexed: 03/27/2025]
Abstract
In Arabidopsis thaliana, lateral root (LR) development requires spatial accommodation responses in overlying endodermal cells. This includes loss of cell volume whilst maintaining membrane integrity to allow the expansion of the underlying LR primordia (LRPs). These accommodation responses are regulated by auxin-mediated signaling, specifically through Aux/IAA proteins, involving IAA3/SHY2. Plants that express a stabilized version of SHY2 (shy2-2) in differentiated endodermal cells, CASP1pro::shy2-2 plants, fail to make LRs. Exogenous treatment with 1-naphthaleneacetic acid (NAA) was reported to partially restore LR formation in this spatial accommodation mutant. Using treatments with auxins having different transport properties, such as NAA, indole-3-acetic acid (IAA), and 2,4-dichlorophenoxyacetic acid (2,4-D), we assessed the ability of each auxin to rescue LR formation in CASP1pro::shy2-2 roots. This revealed that IAA is the most effective in partially restoring LR development, NAA is effective in inducing LRPs but cannot maintain their canonical phenotype, whereas 2,4-D induces non-controlled cell divisions. In addition, we show that in CASP1pro::shy2-2 roots, AUX1 appears to be repressed in the zone where oscillation of the auxin response has been described. Our study advances the understanding of auxin-regulated spatial accommodation mechanisms during LRP formation and highlights the complex interplay of auxin transport and signaling in bypassing the endodermal constraints.
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Affiliation(s)
- Thái X Bùi
- Laboratory of Cell and Molecular Biology (LBMC), Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Vinay Shekhar
- Laboratory of Cell and Molecular Biology (LBMC), Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Sophie Marc-Martin
- Laboratory of Cell and Molecular Biology (LBMC), Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Kevin Bellande
- Laboratory of Cell and Molecular Biology (LBMC), Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- IPSiM, University of Montpellier, Montpellier, France
| | - Joop E M Vermeer
- Laboratory of Cell and Molecular Biology (LBMC), Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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Sidhu JS, Lopez-Valdivia I, Strock CF, Schneider HM, Lynch JP. Cortical parenchyma wall width regulates root metabolic cost and maize performance under suboptimal water availability. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:5750-5767. [PMID: 38661441 PMCID: PMC11427841 DOI: 10.1093/jxb/erae191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 04/23/2024] [Indexed: 04/26/2024]
Abstract
We describe how increased root cortical parenchyma wall width (CPW) can improve tolerance to drought stress in maize by reducing the metabolic costs of soil exploration. Significant variation (1.0-5.0 µm) for CPW was observed in maize germplasm. The functional-structural model RootSlice predicts that increasing CPW from 2 µm to 4 µm is associated with a ~15% reduction in root cortical cytoplasmic volume, respiration rate, and nitrogen content. Analysis of genotypes with contrasting CPW grown with and without water stress in the field confirms that increased CPW is correlated with an ~32-42% decrease in root respiration. Under water stress in the field, increased CPW is correlated with 125% increased stomatal conductance, 325% increased leaf CO2 assimilation rate, 73-78% increased shoot biomass, and 92-108% increased yield. CPW was correlated with leaf mesophyll midrib parenchyma wall width, indicating pleiotropy. Genome-wide association study analysis identified candidate genes underlying CPW. OpenSimRoot modeling predicts that a reduction in root respiration due to increased CPW would also benefit maize growth under suboptimal nitrogen, which requires empirical testing. We propose CPW as a new phene that has utility under edaphic stress meriting further investigation.
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Affiliation(s)
- Jagdeep Singh Sidhu
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA
| | - Ivan Lopez-Valdivia
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA
| | - Christopher F Strock
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA
| | - Hannah M Schneider
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Physiology and Cell Biology, Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstr 3, D-06466 Seeland, Germany
| | - Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA
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de Jesus Vieira Teixeira C, Bellande K, van der Schuren A, O'Connor D, Hardtke CS, Vermeer JEM. An atlas of Brachypodium distachyon lateral root development. Biol Open 2024; 13:bio060531. [PMID: 39158386 PMCID: PMC11391822 DOI: 10.1242/bio.060531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 08/05/2024] [Indexed: 08/20/2024] Open
Abstract
The root system of plants is a vital part for successful development and adaptation to different soil types and environments. A major determinant of the shape of a plant root system is the formation of lateral roots, allowing for expansion of the root system. Arabidopsis thaliana, with its simple root anatomy, has been extensively studied to reveal the genetic program underlying root branching. However, to get a more general understanding of lateral root development, comparative studies in species with a more complex root anatomy are required. Here, by combining optimized clearing methods and histology, we describe an atlas of lateral root development in Brachypodium distachyon, a wild, temperate grass species. We show that lateral roots initiate from enlarged phloem pole pericycle cells and that the overlying endodermis reactivates its cell cycle and eventually forms the root cap. In addition, auxin signaling reported by the DR5 reporter was not detected in the phloem pole pericycle cells or young primordia. In contrast, auxin signaling was activated in the overlying cortical cell layers, including the exodermis. Thus, Brachypodium is a valuable model to investigate how signaling pathways and cellular responses have been repurposed to facilitate lateral root organogenesis.
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Affiliation(s)
| | - Kevin Bellande
- Laboratory of Molecular and Cell Biology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
- IPSiM, University of Montpellier, CNRS, INRAE, Institut Agro, 34060 Montpellier, France
| | - Alja van der Schuren
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Devin O'Connor
- Sainsbury Lab, University of Cambridge, CB2 1LR Cambridge, UK
| | - Christian S. Hardtke
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Joop E. M Vermeer
- Laboratory of Molecular and Cell Biology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
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Lynch JP, Galindo-Castañeda T, Schneider HM, Sidhu JS, Rangarajan H, York LM. Root phenotypes for improved nitrogen capture. PLANT AND SOIL 2023; 502:31-85. [PMID: 39323575 PMCID: PMC11420291 DOI: 10.1007/s11104-023-06301-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/18/2023] [Indexed: 09/27/2024]
Abstract
Background Suboptimal nitrogen availability is a primary constraint for crop production in low-input agroecosystems, while nitrogen fertilization is a primary contributor to the energy, economic, and environmental costs of crop production in high-input agroecosystems. In this article we consider avenues to develop crops with improved nitrogen capture and reduced requirement for nitrogen fertilizer. Scope Intraspecific variation for an array of root phenotypes has been associated with improved nitrogen capture in cereal crops, including architectural phenotypes that colocalize root foraging with nitrogen availability in the soil; anatomical phenotypes that reduce the metabolic costs of soil exploration, improve penetration of hard soil, and exploit the rhizosphere; subcellular phenotypes that reduce the nitrogen requirement of plant tissue; molecular phenotypes exhibiting optimized nitrate uptake kinetics; and rhizosphere phenotypes that optimize associations with the rhizosphere microbiome. For each of these topics we provide examples of root phenotypes which merit attention as potential selection targets for crop improvement. Several cross-cutting issues are addressed including the importance of soil hydrology and impedance, phenotypic plasticity, integrated phenotypes, in silico modeling, and breeding strategies using high throughput phenotyping for co-optimization of multiple phenes. Conclusions Substantial phenotypic variation exists in crop germplasm for an array of root phenotypes that improve nitrogen capture. Although this topic merits greater research attention than it currently receives, we have adequate understanding and tools to develop crops with improved nitrogen capture. Root phenotypes are underutilized yet attractive breeding targets for the development of the nitrogen efficient crops urgently needed in global agriculture.
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Affiliation(s)
- Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802 USA
| | | | - Hannah M Schneider
- Department of Plant Sciences, Wageningen University and Research, PO Box 430, 6700AK Wageningen, The Netherlands
| | - Jagdeep Singh Sidhu
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802 USA
| | - Harini Rangarajan
- Department of Plant Science, The Pennsylvania State University, University Park, PA 16802 USA
| | - Larry M York
- Biosciences Division and Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN 37830 USA
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Lopez-Valdivia I, Yang X, Lynch JP. Large root cortical cells and reduced cortical cell files improve growth under suboptimal nitrogen in silico. PLANT PHYSIOLOGY 2023:kiad214. [PMID: 37040571 DOI: 10.1093/plphys/kiad214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/13/2023] [Accepted: 03/13/2023] [Indexed: 06/19/2023]
Abstract
Suboptimal nitrogen availability is a primary constraint to plant growth. We used OpenSimRoot, a functional-structural plant/soil model, to test the hypothesis that larger root cortical cell size (CCS), reduced cortical cell file number (CCFN), and their interactions with root cortical aerenchyma (RCA) and lateral root branching density (LRBD) are useful adaptations to suboptimal soil nitrogen availability in maize (Zea mays). Reduced CCFN increased shoot dry weight over 80%. Reduced respiration, reduced nitrogen content, and reduced root diameter accounted for 23%, 20%, and 33% of increased shoot biomass, respectively. Large CCS increased shoot biomass by 24% compared with small CCS. When simulated independently, reduced respiration and reduced nutrient content increased the shoot biomass by 14% and 3%, respectively. However, increased root diameter resulting from large CCS decreased shoot biomass by 4% due to an increase in root metabolic cost. Under moderate N stress, integrated phenotypes with reduced CCFN, large CCS, and high RCA improved shoot biomass in silt loam and loamy sand soils. In contrast, integrated phenotypes composed of reduced CCFN, large CCS and reduced lateral root branching density had the greatest growth in silt loam, while phenotypes with reduced CCFN, large CCS and high LRBD were the best performers in loamy sands. Our results support the hypothesis that larger CCS, reduced CCFN, and their interactions with RCA and LRBD could increase nitrogen acquisition by reducing root respiration and root nutrient demand. Phene synergisms may exist between CCS, CCFN, and LRBD. CCS and CCFN merit consideration for breeding cereal crops with improved nitrogen acquisition, which is critical for global food security.
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Affiliation(s)
- Ivan Lopez-Valdivia
- Department of Plant Science, The Pennsylvania State University, University Park, PA, U.S.A., 16802
| | - Xiyu Yang
- Department of Plant Science, The Pennsylvania State University, University Park, PA, U.S.A., 16802
| | - Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA, U.S.A., 16802
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Schäfer ED, Ajmera I, Farcot E, Owen MR, Band LR, Lynch JP. In silico evidence for the utility of parsimonious root phenotypes for improved vegetative growth and carbon sequestration under drought. FRONTIERS IN PLANT SCIENCE 2022; 13:1010165. [PMID: 36466274 PMCID: PMC9713484 DOI: 10.3389/fpls.2022.1010165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/03/2022] [Indexed: 05/11/2023]
Abstract
Drought is a primary constraint to crop yields and climate change is expected to increase the frequency and severity of drought stress in the future. It has been hypothesized that crops can be made more resistant to drought and better able to sequester atmospheric carbon in the soil by selecting appropriate root phenotypes. We introduce OpenSimRoot_v2, an upgraded version of the functional-structural plant/soil model OpenSimRoot, and use it to test the utility of a maize root phenotype with fewer and steeper axial roots, reduced lateral root branching density, and more aerenchyma formation (i.e. the 'Steep, Cheap, and Deep' (SCD) ideotype) and different combinations of underlying SCD root phene states under rainfed and drought conditions in three distinct maize growing pedoclimatic environments in the USA, Nigeria, and Mexico. In all environments where plants are subjected to drought stress the SCD ideotype as well as several intermediate phenotypes lead to greater shoot biomass after 42 days. As an additional advantage, the amount of carbon deposited below 50 cm in the soil is twice as great for the SCD phenotype as for the reference phenotype in 5 out of 6 simulated environments. We conclude that crop growth and deep soil carbon deposition can be improved by breeding maize plants with fewer axial roots, reduced lateral root branching density, and more aerenchyma formation.
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Affiliation(s)
- Ernst D. Schäfer
- Department of Plant Science, Pennysylvania State University, State College, PA, United States
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Ishan Ajmera
- Department of Plant Science, Pennysylvania State University, State College, PA, United States
| | - Etienne Farcot
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Markus R. Owen
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Leah R. Band
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
- School of Biosciences, University of Nottingham, Nottingham, United Kingdom
| | - Jonathan P. Lynch
- Department of Plant Science, Pennysylvania State University, State College, PA, United States
- *Correspondence: Jonathan P. Lynch,
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