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Lynch JP. Harnessing root architecture to address global challenges. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 109:415-431. [PMID: 34724260 PMCID: PMC9299910 DOI: 10.1111/tpj.15560] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 05/06/2023]
Abstract
Root architecture can be targeted in breeding programs to develop crops with better capture of water and nutrients. In rich nations, such crops would reduce production costs and environmental pollution and, in developing nations, they would improve food security and economic development. Crops with deeper roots would have better climate resilience while also sequestering atmospheric CO2 . Deeper rooting, which improves water and N capture, is facilitated by steeper root growth angles, fewer axial roots, reduced lateral branching, and anatomical phenotypes that reduce the metabolic cost of root tissue. Mechanical impedance, hypoxia, and Al toxicity are constraints to subsoil exploration. To improve topsoil foraging for P, K, and other shallow resources, shallower root growth angles, more axial roots, and greater lateral branching are beneficial, as are metabolically cheap roots. In high-input systems, parsimonious root phenotypes that focus on water capture may be advantageous. The growing prevalence of Conservation Agriculture is shifting the mechanical impedance characteristics of cultivated soils in ways that may favor plastic root phenotypes capable of exploiting low resistance pathways to the subsoil. Root ideotypes for many low-input systems would not be optimized for any one function, but would be resilient against an array of biotic and abiotic challenges. Root hairs, reduced metabolic cost, and developmental regulation of plasticity may be useful in all environments. The fitness landscape of integrated root phenotypes is large and complex, and hence will benefit from in silico tools. Understanding and harnessing root architecture for crop improvement is a transdisciplinary opportunity to address global challenges.
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Affiliation(s)
- Jonathan P. Lynch
- Department of Plant ScienceThe Pennsylvania State UniversityUniversity ParkPA16802USA
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52
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Burridge JD, Grondin A, Vadez V. Optimizing Crop Water Use for Drought and Climate Change Adaptation Requires a Multi-Scale Approach. FRONTIERS IN PLANT SCIENCE 2022; 13:824720. [PMID: 35574091 PMCID: PMC9100818 DOI: 10.3389/fpls.2022.824720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/11/2022] [Indexed: 05/09/2023]
Abstract
Selection criteria that co-optimize water use efficiency and yield are needed to promote plant productivity in increasingly challenging and variable drought scenarios, particularly dryland cereals in the semi-arid tropics. Optimizing water use efficiency and yield fundamentally involves transpiration dynamics, where restriction of maximum transpiration rate helps to avoid early crop failure, while maximizing grain filling. Transpiration restriction can be regulated by multiple mechanisms and involves cross-organ coordination. This coordination involves complex feedbacks and feedforwards over time scales ranging from minutes to weeks, and from spatial scales ranging from cell membrane to crop canopy. Aquaporins have direct effect but various compensation and coordination pathways involve phenology, relative root and shoot growth, shoot architecture, root length distribution profile, as well as other architectural and anatomical aspects of plant form and function. We propose gravimetric phenotyping as an integrative, cross-scale solution to understand the dynamic, interwoven, and context-dependent coordination of transpiration regulation. The most fruitful breeding strategy is likely to be that which maintains focus on the phene of interest, namely, daily and season level transpiration dynamics. This direct selection approach is more precise than yield-based selection but sufficiently integrative to capture attenuating and complementary factors.
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Affiliation(s)
- James D. Burridge
- DIADE Group, Cereal Root Systems, Institute de Recherche pour le Développement/Université de Montpellier, Montpellier, France
- *Correspondence: James D. Burridge,
| | - Alexandre Grondin
- DIADE Group, Cereal Root Systems, Institute de Recherche pour le Développement/Université de Montpellier, Montpellier, France
- Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, Laboratoire Mixte International, Dakar, Senegal
- Centre d’Étude Régional pour l’Amélioration de l’Adaptation à la Sécheresse, Thiès, Senegal
| | - Vincent Vadez
- DIADE Group, Cereal Root Systems, Institute de Recherche pour le Développement/Université de Montpellier, Montpellier, France
- Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, Laboratoire Mixte International, Dakar, Senegal
- Centre d’Étude Régional pour l’Amélioration de l’Adaptation à la Sécheresse, Thiès, Senegal
- International Crops Research Institute for Semi-Arid Tropics (ICRISAT), Patancheru, India
- Vincent Vadez,
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53
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Wang X, Zhang J, Wang H, Rengel Z, Li H. Plasticity and co‐variation of root traits govern differential phosphorus acquisition among 20 wheat genotypes. OIKOS 2021. [DOI: 10.1111/oik.08606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Xin‐Xin Wang
- Mountain Area Research Inst., Hebei Agricultural Univ. Baoding PR China
- State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agricultural Univ. Hebei Baoding PR China
| | - Jiaqi Zhang
- Mountain Area Research Inst., Hebei Agricultural Univ. Baoding PR China
| | - Hong Wang
- Mountain Area Research Inst., Hebei Agricultural Univ. Baoding PR China
| | - Zed Rengel
- Soil Science&Plant Nutrition, UWA School of Agriculture and Environment, The Univ. of Western Australia Perth Australia
- Inst. for Adriatic Crops and Karst Reclamation Split Croatia
| | - Hongbo Li
- Inst. of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences Beijing PR China
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Zeng D, Li M, Jiang N, Ju Y, Schreiber H, Chambers E, Letscher D, Ju T, Topp CN. TopoRoot: a method for computing hierarchy and fine-grained traits of maize roots from 3D imaging. PLANT METHODS 2021; 17:127. [PMID: 34903248 PMCID: PMC8667396 DOI: 10.1186/s13007-021-00829-z] [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: 08/24/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND 3D imaging, such as X-ray CT and MRI, has been widely deployed to study plant root structures. Many computational tools exist to extract coarse-grained features from 3D root images, such as total volume, root number and total root length. However, methods that can accurately and efficiently compute fine-grained root traits, such as root number and geometry at each hierarchy level, are still lacking. These traits would allow biologists to gain deeper insights into the root system architecture. RESULTS We present TopoRoot, a high-throughput computational method that computes fine-grained architectural traits from 3D images of maize root crowns or root systems. These traits include the number, length, thickness, angle, tortuosity, and number of children for the roots at each level of the hierarchy. TopoRoot combines state-of-the-art algorithms in computer graphics, such as topological simplification and geometric skeletonization, with customized heuristics for robustly obtaining the branching structure and hierarchical information. TopoRoot is validated on both CT scans of excavated field-grown root crowns and simulated images of root systems, and in both cases, it was shown to improve the accuracy of traits over existing methods. TopoRoot runs within a few minutes on a desktop workstation for images at the resolution range of 400^3, with minimal need for human intervention in the form of setting three intensity thresholds per image. CONCLUSIONS TopoRoot improves the state-of-the-art methods in obtaining more accurate and comprehensive fine-grained traits of maize roots from 3D imaging. The automation and efficiency make TopoRoot suitable for batch processing on large numbers of root images. Our method is thus useful for phenomic studies aimed at finding the genetic basis behind root system architecture and the subsequent development of more productive crops.
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Affiliation(s)
- Dan Zeng
- Department of Computer Science and Engineering, Washington University in St. Louis, Saint Louis, MO, 63130, USA.
| | - Mao Li
- Donald Danforth Plant Science Center, Saint Louis, MO, 63132, USA
| | - Ni Jiang
- Donald Danforth Plant Science Center, Saint Louis, MO, 63132, USA
| | - Yiwen Ju
- Department of Computer Science and Engineering, Washington University in St. Louis, Saint Louis, MO, 63130, USA
| | - Hannah Schreiber
- Department of Computer Science, Saint Louis University, Saint Louis, MO, 63103, USA
| | - Erin Chambers
- Department of Computer Science, Saint Louis University, Saint Louis, MO, 63103, USA
| | - David Letscher
- Department of Computer Science, Saint Louis University, Saint Louis, MO, 63103, USA
| | - Tao Ju
- Department of Computer Science and Engineering, Washington University in St. Louis, Saint Louis, MO, 63130, USA
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55
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Bucciarelli B, Xu Z, Ao S, Cao Y, Monteros MJ, Topp CN, Samac DA. Phenotyping seedlings for selection of root system architecture in alfalfa (Medicago sativa L.). PLANT METHODS 2021; 17:125. [PMID: 34876178 PMCID: PMC8650460 DOI: 10.1186/s13007-021-00825-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/26/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND The root system architecture (RSA) of alfalfa (Medicago sativa L.) affects biomass production by influencing water and nutrient uptake, including nitrogen fixation. Further, roots are important for storing carbohydrates that are needed for regrowth in spring and after each harvest. Previous selection for a greater number of branched and fibrous roots significantly increased alfalfa biomass yield. However, phenotyping root systems of mature alfalfa plant is labor-intensive, time-consuming, and subject to environmental variability and human error. High-throughput and detailed phenotyping methods are needed to accelerate the development of alfalfa germplasm with distinct RSAs adapted to specific environmental conditions and for enhancing productivity in elite germplasm. In this study methods were developed for phenotyping 14-day-old alfalfa seedlings to identify measurable root traits that are highly heritable and can differentiate plants with either a branched or a tap rooted phenotype. Plants were grown in a soil-free mixture under controlled conditions, then the root systems were imaged with a flatbed scanner and measured using WinRhizo software. RESULTS The branched root plants had a significantly greater number of tertiary roots and significantly longer tertiary roots relative to the tap rooted plants. Additionally, the branch rooted population had significantly more secondary roots > 2.5 cm relative to the tap rooted population. These two parameters distinguishing phenotypes were confirmed using two machine learning algorithms, Random Forest and Gradient Boosting Machines. Plants selected as seedlings for the branch rooted or tap rooted phenotypes were used in crossing blocks that resulted in a genetic gain of 10%, consistent with the previous selection strategy that utilized manual root scoring to phenotype 22-week-old-plants. Heritability analysis of various root architecture parameters from selected seedlings showed tertiary root length and number are highly heritable with values of 0.74 and 0.79, respectively. CONCLUSIONS The results show that seedling root phenotyping is a reliable tool that can be used for alfalfa germplasm selection and breeding. Phenotypic selection of RSA in seedlings reduced time for selection by 20 weeks, significantly accelerating the breeding cycle.
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Affiliation(s)
- Bruna Bucciarelli
- Department of Agronomy and Plant Genetics, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN, 55108, USA
| | - Zhanyou Xu
- USDA-ARS, Plant Science Research Unit, 1991 Upper Buford Circle, St. Paul, MN, 55108, USA
| | - Samadangla Ao
- Department of Agronomy and Plant Genetics, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN, 55108, USA
- Kohima Science College, Jotsoma, 797002, Nagaland, India
| | - Yuanyuan Cao
- Department of Plant Pathology, University of Minnesota, 1991 Upper Buford Circle, 495 Borlaug Hall, St. Paul, MN, 55108, USA
- School of Life Sciences, Anhui Agricultural University, Hefei, 230036, Anhui, China
| | - Maria J Monteros
- Noble Research Institute, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
- Bayer Crop Science, Chesterfield, MO, 63017, USA
| | - Christopher N Topp
- Donald Danforth Plant Science Center, 975 N Warson Road, Olivette, MO, 63132, USA
| | - Deborah A Samac
- USDA-ARS, Plant Science Research Unit, 1991 Upper Buford Circle, St. Paul, MN, 55108, USA.
- Department of Plant Pathology, University of Minnesota, 1991 Upper Buford Circle, 495 Borlaug Hall, St. Paul, MN, 55108, USA.
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56
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Karlova R, Boer D, Hayes S, Testerink C. Root plasticity under abiotic stress. PLANT PHYSIOLOGY 2021; 187:1057-1070. [PMID: 34734279 PMCID: PMC8566202 DOI: 10.1093/plphys/kiab392] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/25/2021] [Indexed: 05/08/2023]
Abstract
Abiotic stresses increasingly threaten existing ecological and agricultural systems across the globe. Plant roots perceive these stresses in the soil and adapt their architecture accordingly. This review provides insights into recent discoveries showing the importance of root system architecture (RSA) and plasticity for the survival and development of plants under heat, cold, drought, salt, and flooding stress. In addition, we review the molecular regulation and hormonal pathways involved in controlling RSA plasticity, main root growth, branching and lateral root growth, root hair development, and formation of adventitious roots. Several stresses affect root anatomy by causing aerenchyma formation, lignin and suberin deposition, and Casparian strip modulation. Roots can also actively grow toward favorable soil conditions and avoid environments detrimental to their development. Recent advances in understanding the cellular mechanisms behind these different root tropisms are discussed. Understanding root plasticity will be instrumental for the development of crops that are resilient in the face of abiotic stress.
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Affiliation(s)
- Rumyana Karlova
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Damian Boer
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Scott Hayes
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Christa Testerink
- Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Author for communication:
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57
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Guo H, Ayalew H, Seethepalli A, Dhakal K, Griffiths M, Ma X, York LM. Functional phenomics and genetics of the root economics space in winter wheat using high-throughput phenotyping of respiration and architecture. THE NEW PHYTOLOGIST 2021; 232:98-112. [PMID: 33683730 PMCID: PMC8518983 DOI: 10.1111/nph.17329] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/26/2021] [Indexed: 05/05/2023]
Abstract
The root economics space is a useful framework for plant ecology but is rarely considered for crop ecophysiology. In order to understand root trait integration in winter wheat, we combined functional phenomics with trait economic theory, utilizing genetic variation, high-throughput phenotyping, and multivariate analyses. We phenotyped a diversity panel of 276 genotypes for root respiration and architectural traits using a novel high-throughput method for CO2 flux and the open-source software RhizoVision Explorer to analyze scanned images. We uncovered substantial variation in specific root respiration (SRR) and specific root length (SRL), which were primary indicators of root metabolic and structural costs. Multiple linear regression analysis indicated that lateral root tips had the greatest SRR, and the residuals from this model were used as a new trait. Specific root respiration was negatively correlated with plant mass. Network analysis, using a Gaussian graphical model, identified root weight, SRL, diameter, and SRR as hub traits. Univariate and multivariate genetic analyses identified genetic regions associated with SRR, SRL, and root branching frequency, and proposed gene candidates. Combining functional phenomics and root economics is a promising approach to improving our understanding of crop ecophysiology. We identified root traits and genomic regions that could be harnessed to breed more efficient crops for sustainable agroecosystems.
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Affiliation(s)
- Haichao Guo
- Noble Research Institute LLC2510 Sam Noble ParkwayArdmoreOK73401USA
| | - Habtamu Ayalew
- Noble Research Institute LLC2510 Sam Noble ParkwayArdmoreOK73401USA
| | | | - Kundan Dhakal
- Noble Research Institute LLC2510 Sam Noble ParkwayArdmoreOK73401USA
| | - Marcus Griffiths
- Noble Research Institute LLC2510 Sam Noble ParkwayArdmoreOK73401USA
| | - Xue‐Feng Ma
- Noble Research Institute LLC2510 Sam Noble ParkwayArdmoreOK73401USA
| | - Larry M. York
- Noble Research Institute LLC2510 Sam Noble ParkwayArdmoreOK73401USA
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58
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Guo H, Ayalew H, Seethepalli A, Dhakal K, Griffiths M, Ma XF, York LM. Functional phenomics and genetics of the root economics space in winter wheat using high-throughput phenotyping of respiration and architecture. THE NEW PHYTOLOGIST 2021. [PMID: 33683730 DOI: 10.1101/2020.11.12.380238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The root economics space is a useful framework for plant ecology but is rarely considered for crop ecophysiology. In order to understand root trait integration in winter wheat, we combined functional phenomics with trait economic theory, utilizing genetic variation, high-throughput phenotyping, and multivariate analyses. We phenotyped a diversity panel of 276 genotypes for root respiration and architectural traits using a novel high-throughput method for CO2 flux and the open-source software RhizoVision Explorer to analyze scanned images. We uncovered substantial variation in specific root respiration (SRR) and specific root length (SRL), which were primary indicators of root metabolic and structural costs. Multiple linear regression analysis indicated that lateral root tips had the greatest SRR, and the residuals from this model were used as a new trait. Specific root respiration was negatively correlated with plant mass. Network analysis, using a Gaussian graphical model, identified root weight, SRL, diameter, and SRR as hub traits. Univariate and multivariate genetic analyses identified genetic regions associated with SRR, SRL, and root branching frequency, and proposed gene candidates. Combining functional phenomics and root economics is a promising approach to improving our understanding of crop ecophysiology. We identified root traits and genomic regions that could be harnessed to breed more efficient crops for sustainable agroecosystems.
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Affiliation(s)
- Haichao Guo
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Habtamu Ayalew
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Anand Seethepalli
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Kundan Dhakal
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Marcus Griffiths
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Xue-Feng Ma
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Larry M York
- Noble Research Institute LLC, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
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59
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Bardhan K, York LM, Hasanuzzaman M, Parekh V, Jena S, Pandya MN. Can smart nutrient applications optimize the plant's hidden half to improve drought resistance? PHYSIOLOGIA PLANTARUM 2021; 172:1007-1015. [PMID: 33432608 DOI: 10.1111/ppl.13332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 11/03/2020] [Accepted: 01/08/2021] [Indexed: 05/14/2023]
Abstract
Global agriculture is challenged with achieving sustainable food security while the climate changes and the threat of drought increases. Much of the research attention has focused on above-ground plant responses with an aim to improve drought resistance. The hidden half, that is, the root system belowground, is receiving increasing attention as the interface of the plant with the soil. Because roots are a sensing organ for nutrients and moisture, we speculate that crop root system traits can be managed using smart nutrient application in order to increase drought resistance. Roots are known to be influenced both by their underlying genetics and also by responses to the environment, termed root plasticity. Though very little is known about the combined effect of water and nutrients on root plasticity, we explore the possibilities of root system manipulation by nutrient application. We compare the effects of different water or nutrient levels on root plasticity and its genetic regulation, with a focus on how this may affect drought resistance. We propose four primary mechanisms through which smart nutrient management can optimize root traits for drought resistance: (1) overall plant vigor, (2) increased root allocation, (3) influence specific root traits, and (4) use smart placement and timing to encourage deep rooting. In the longer term, we envision that beneficial root traits, including plasticity, could be bred into efficient varieties and combined with advanced precision management of water and nutrients to achieve agricultural sustainability.
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Affiliation(s)
- Kirti Bardhan
- Department of Basic Sciences and Humanities, Navsari Agricultural University, Navsari, India
| | - Larry M York
- Noble Research Institute, LLC, Ardmore, Oklahoma, USA
| | - Mirza Hasanuzzaman
- Department of Agronomy, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
| | - Vipulkumar Parekh
- Department of Basic Sciences and Humanities, Navsari Agricultural University, Navsari, India
| | - Suchismita Jena
- Department of Fruit Science, Navsari Agricultural University, Navsari, India
| | - Mansi N Pandya
- Department of Genetics and Plant Breeding, Navsari Agricultural University, Navsari, India
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60
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Hendel E, Bacher H, Oksenberg A, Walia H, Schwartz N, Peleg Z. Deciphering the genetic basis of wheat seminal root anatomy uncovers ancestral axial conductance alleles. PLANT, CELL & ENVIRONMENT 2021; 44:1921-1934. [PMID: 33629405 DOI: 10.1111/pce.14035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/19/2021] [Accepted: 02/21/2021] [Indexed: 05/24/2023]
Abstract
Root axial conductance, which describes the ability of water to move through the xylem, contributes to the rate of water uptake from the soil throughout the whole plant lifecycle. Under the rainfed wheat agro-system, grain-filling is typically occurring during declining water availability (i.e., terminal drought). Therefore, preserving soil water moisture during grain filling could serve as a key adaptive trait. We hypothesized that lower wheat root axial conductance can promote higher yields under terminal drought. A segregating population derived from a cross between durum wheat and its direct progenitor wild emmer wheat was used to underpin the genetic basis of seminal root architectural and functional traits. We detected 75 QTL associated with seminal roots morphological, anatomical and physiological traits, with several hotspots harbouring co-localized QTL. We further validated the axial conductance and central metaxylem QTL using wild introgression lines. Field-based characterization of genotypes with contrasting axial conductance suggested the contribution of low axial conductance as a mechanism for water conservation during grain filling and consequent increase in grain size and yield. Our findings underscore the potential of harnessing wild alleles to reshape the wheat root system architecture and associated hydraulic properties for greater adaptability under changing climate.
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Affiliation(s)
- Elisha Hendel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
- The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Harel Bacher
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Adi Oksenberg
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Harkamal Walia
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Nimrod Schwartz
- The Institute of Environmental Sciences, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Zvi Peleg
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
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61
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Chapman JM, Muday GK. Flavonols modulate lateral root emergence by scavenging reactive oxygen species in Arabidopsis thaliana. J Biol Chem 2021; 296:100222. [PMID: 33839683 PMCID: PMC7948594 DOI: 10.1074/jbc.ra120.014543] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 12/19/2020] [Accepted: 12/21/2020] [Indexed: 11/20/2022] Open
Abstract
Flavonoids are a class of specialized metabolites with subclasses including flavonols and anthocyanins, which have unique properties as antioxidants. Flavonoids modulate plant development, but whether and how they impact lateral root development is unclear. We examined potential roles for flavonols in this process using Arabidopsis thaliana mutants with defects in genes encoding key enzymes in flavonoid biosynthesis. We observed the tt4 and fls1 mutants, which produce no flavonols, have increased lateral root emergence. The tt4 root phenotype was reversed by genetic and chemical complementation. To more specifically define the flavonoids involved, we tested an array of flavonoid biosynthetic mutants, eliminating roles for anthocyanins and the flavonols quercetin and isorhamnetin in modulating lateral root development. Instead, two tt7 mutant alleles, with defects in a branchpoint enzyme blocking quercetin biosynthesis, formed reduced numbers of lateral roots and tt7-2 had elevated levels of kaempferol. Using a flavonol-specific dye, we observed that in the tt7-2 mutant, kaempferol accumulated within lateral root primordia at higher levels than wild-type. These data are consistent with kaempferol, or downstream derivatives, acting as a negative regulator of lateral root emergence. We examined ROS accumulation using ROS-responsive probes and found reduced fluorescence of a superoxide-selective probe within the primordia of tt7-2 compared with wild-type, but not in the tt4 mutant, consistent with opposite effects of these mutants on lateral root emergence. These results support a model in which increased level of kaempferol in the lateral root primordia of tt7-2 reduces superoxide concentration and ROS-stimulated lateral root emergence.
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Affiliation(s)
- Jordan M Chapman
- Biology Department, Wake Forest University, Winston Salem, North Carolina, USA
| | - Gloria K Muday
- Biology Department, Wake Forest University, Winston Salem, North Carolina, USA.
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62
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Does Elevated [CO 2] Only Increase Root Growth in the Topsoil? A FACE Study with Lentil in a Semi-Arid Environment. PLANTS 2021; 10:plants10040612. [PMID: 33804836 PMCID: PMC8063810 DOI: 10.3390/plants10040612] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 11/16/2022]
Abstract
Atmospheric carbon dioxide concentrations [CO2] are increasing steadily. Some reports have shown that root growth in grain crops is mostly stimulated in the topsoil rather than evenly throughout the soil profile by e[CO2], which is not optimal for crops grown in semi-arid environments with strong reliance on stored water. An experiment was conducted during the 2014 and 2015 growing seasons with two lentil (Lens culinaris) genotypes grown under Free Air CO2 Enrichment (FACE) in which root growth was observed non-destructively with mini-rhizotrons approximately every 2-3 weeks. Root growth was not always statistically increased by e[CO2] and not consistently between depths and genotypes. In 2014, root growth in the top 15 cm of the soil profile (topsoil) was indeed increased by e[CO2], but increases at lower depths (30-45 cm) later in the season were greater than in the topsoil. In 2015, e[CO2] only increased root length in the topsoil for one genotype, potentially reflecting the lack of plant available soil water between 30-60 cm until recharged by irrigation during grain filling. Our limited data to compare responses to e[CO2] showed that root length increases in the topsoil were correlated with a lower yield response to e[CO2]. The increase in yield response was rather correlated with increases in root growth below 30 cm depth.
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63
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Gebre MG, Earl HJ. Soil Water Deficit and Fertilizer Placement Effects on Root Biomass Distribution, Soil Water Extraction, Water Use, Yield, and Yield Components of Soybean [ Glycine max (L.) Merr.] Grown in 1-m Rooting Columns. FRONTIERS IN PLANT SCIENCE 2021; 12:581127. [PMID: 33790918 PMCID: PMC8005719 DOI: 10.3389/fpls.2021.581127] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 02/22/2021] [Indexed: 05/24/2023]
Abstract
Typical small-pot culture systems are not ideal for controlled environment phenotyping for drought tolerance, especially for root-related traits. We grew soybean plants in a greenhouse in 1-m rooting columns filled with amended field soil to test the effects of drought stress on water use, root growth, shoot growth, and yield components. There were three watering treatments, beginning at first flower: watered daily to 100% of the maximum soil water holding capacity (control), 75% (mild drought stress), or 50% (drought stress). We also tested whether applying fertilizer throughout the 1-m soil depth instead of only in the top 30 cm would modify root distribution by depth in the soil profile and thereby affect responses to drought stress. Distributing the fertilizer over the entire 1-m soil depth altered the root biomass distribution and volumetric soil water content profile at first flower, but these effects did not persist to maturity and thus did not enhance drought tolerance. Compared to the control (100%) watering treatment, the 50% watering treatment significantly reduced seed yield by 40%, pod number by 42%, seeds per pod by 3%, shoot dry matter by 48%, root dry matter by 53%, and water use by 52%. Effects of the 75% watering treatment were intermittent between the 50 and 100%. The 50% treatment significantly increased root-to-shoot dry matter ratio by 23%, harvest index by 17%, and water-use efficiency by 7%. Seed size was not affected by either fertilizer or watering treatments. More than 65% of the total root dry matter was distributed in the upper 20 cm of the profile in all watering treatments. However, the two drought stress treatments, especially the mild drought stress, had a greater proportion of root dry matter located in the deeper soil layers. The overall coefficient of variation for seed yield was low at 5.3%, suggesting good repeatability of the treatments. Drought stress imposed in this culture system affected yield components similarly to what is observed in the field, with pod number being the component most strongly affected. This system should be useful for identifying variation among soybean lines for a wide variety of traits related to drought tolerance.
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64
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Schneider HM, Yang JT, Brown KM, Lynch JP. Nodal root diameter and node number in maize ( Zea mays L.) interact to influence plant growth under nitrogen stress. PLANT DIRECT 2021; 5:e00310. [PMID: 33748655 PMCID: PMC7963125 DOI: 10.1002/pld3.310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 01/23/2021] [Accepted: 01/25/2021] [Indexed: 05/11/2023]
Abstract
Under nitrogen limitation, plants increase resource allocation to root growth relative to shoot growth. The utility of various root architectural and anatomical phenotypes for nitrogen acquisition are not well understood. Nodal root number and root cross-sectional area were evaluated in maize in field and greenhouse environments. Nodal root number and root cross-sectional area were inversely correlated under both high and low nitrogen conditions. Attenuated emergence of root nodes, as opposed to differences in the number of axial roots per node, was associated with substantially reduced root number. Greater root cross-sectional area was associated with a greater stele area and number of cortical cell files. Genotypes that produced few, thick nodal roots rather than many, thin nodal roots had deeper rooting and better shoot growth in low nitrogen environments. Fewer nodal roots offset the respiratory and nitrogen costs of thicker diameter roots, since total nodal root respiration and nitrogen content was similar for genotypes with many, thin and few, thick nodal roots. We propose that few, thick nodal roots may enable greater capture of deep soil nitrogen and improve plant performance under nitrogen stress. Synergistic interactions between an architectural and anatomical trait may be an important strategy for nitrogen acquisition. Understanding trait interactions among different root nodes has important implications in for improving crop nutrient uptake and stress tolerance.
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Affiliation(s)
- Hannah M. Schneider
- Department of Plant ScienceThe Pennsylvania State UniversityUniversity ParkPAUSA
| | - Jennifer T. Yang
- Department of Plant ScienceThe Pennsylvania State UniversityUniversity ParkPAUSA
- Present address:
Wellesley CollegeWellesleyMAUSA
| | - Kathleen M. Brown
- Department of Plant ScienceThe Pennsylvania State UniversityUniversity ParkPAUSA
| | - Jonathan P. Lynch
- Department of Plant ScienceThe Pennsylvania State UniversityUniversity ParkPAUSA
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65
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Yamauchi T, Pedersen O, Nakazono M, Tsutsumi N. Key root traits of Poaceae for adaptation to soil water gradients. THE NEW PHYTOLOGIST 2021; 229:3133-3140. [PMID: 33222170 PMCID: PMC7986152 DOI: 10.1111/nph.17093] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 11/12/2020] [Indexed: 05/16/2023]
Abstract
Drought and flooding are contrasting abiotic stressors for plants. Evidence is accumulating for root anatomical traits being essential for the adaptation to drought or flooding. However, an integrated approach to comprehensively understand root anatomical traits has not yet been established. Here we analysed the root anatomical traits of 18 wild Poaceae species differing in adaptation to a range of soil water content. Regression model analyses revealed the optimal anatomical traits that were required by the plants to adapt to low or high soil water content. While the area and number of each root tissue (e.g. stele, cortex, xylem or aerenchyma) were not strongly correlated to the soil water content, the ratio of the root tissue areas (cortex to stele ratio (CSR), xylem to stele ratio (XSR) and aerenchyma to cortex ratio (ACR)) could fully explain the adaptations of the wild Poaceae species to the soil water gradients. Our results demonstrate that the optimal anatomical traits for the adaptations to soil water content can be determined by three indices (i.e. CSR, XSR and ACR), and thus we propose that these root anatomical indices can be used to improve the tolerance of crops to drought and flooding stresses.
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Affiliation(s)
- Takaki Yamauchi
- Japan Science and Technology AgencyPRESTOKawaguchiSaitama332‐0012Japan
- Graduate School of Agricultural and Life SciencesThe University of TokyoBunkyoTokyo113‐8657Japan
| | - Ole Pedersen
- Freshwater Biological LaboratoryDepartment of BiologyUniversity of CopenhagenUniversitetsparken 4, 3 floorCopenhagen2100Denmark
- UWA School of Agriculture and EnvironmentFaculty of ScienceThe University of Western AustraliaPerthWA6009Australia
| | - Mikio Nakazono
- UWA School of Agriculture and EnvironmentFaculty of ScienceThe University of Western AustraliaPerthWA6009Australia
- Graduate School of Bioagricultural SciencesNagoya UniversityNagoyaAichi464‐8601Japan
| | - Nobuhiro Tsutsumi
- Graduate School of Agricultural and Life SciencesThe University of TokyoBunkyoTokyo113‐8657Japan
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66
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Schneider HM, Strock CF, Hanlon MT, Vanhees DJ, Perkins AC, Ajmera IB, Sidhu JS, Mooney SJ, Brown KM, Lynch JP. Multiseriate cortical sclerenchyma enhance root penetration in compacted soils. Proc Natl Acad Sci U S A 2021; 118:e2012087118. [PMID: 33536333 PMCID: PMC8017984 DOI: 10.1073/pnas.2012087118] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mechanical impedance limits soil exploration and resource capture by plant roots. We examine the role of root anatomy in regulating plant adaptation to mechanical impedance and identify a root anatomical phene in maize (Zea mays) and wheat (Triticum aestivum) associated with penetration of hard soil: Multiseriate cortical sclerenchyma (MCS). We characterize this trait and evaluate the utility of MCS for root penetration in compacted soils. Roots with MCS had a greater cell wall-to-lumen ratio and a distinct UV emission spectrum in outer cortical cells. Genome-wide association mapping revealed that MCS is heritable and genetically controlled. We identified a candidate gene associated with MCS. Across all root classes and nodal positions, maize genotypes with MCS had 13% greater root lignin concentration compared to genotypes without MCS. Genotypes without MCS formed MCS upon exogenous ethylene exposure. Genotypes with MCS had greater lignin concentration and bending strength at the root tip. In controlled environments, MCS in maize and wheat was associated improved root tensile strength and increased penetration ability in compacted soils. Maize genotypes with MCS had root systems with 22% greater depth and 49% greater shoot biomass in compacted soils in the field compared to lines without MCS. Of the lines we assessed, MCS was present in 30 to 50% of modern maize, wheat, and barley cultivars but was absent in teosinte and wild and landrace accessions of wheat and barley. MCS merits investigation as a trait for improving plant performance in maize, wheat, and other grasses under edaphic stress.
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Affiliation(s)
- Hannah M Schneider
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802
| | - Christopher F Strock
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802
| | - Meredith T Hanlon
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802
| | - Dorien J Vanhees
- Division of Agricultural and Environment Sciences, School of Biosciences, University of Nottingham, Leicestershire LE12 5RD, United Kingdom
- The James Hutton Institute, Invergowrie DD2 5DA, United Kingdom
| | - Alden C Perkins
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802
| | - Ishan B Ajmera
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802
| | - Jagdeep Singh Sidhu
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802
| | - Sacha J Mooney
- Division of Agricultural and Environment Sciences, School of Biosciences, University of Nottingham, Leicestershire LE12 5RD, United Kingdom
- Centre for Plant Integrative Biology, University of Nottingham, Leicestershire LE12 5RD, United Kingdom
| | - Kathleen M Brown
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802
| | - Jonathan P Lynch
- Department of Plant Science, Pennsylvania State University, University Park, PA 16802;
- Division of Agricultural and Environment Sciences, School of Biosciences, University of Nottingham, Leicestershire LE12 5RD, United Kingdom
- Centre for Plant Integrative Biology, University of Nottingham, Leicestershire LE12 5RD, United Kingdom
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67
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Root Response of Moso Bamboo (Phyllostachys edulis (Carrière) J. Houz.) Seedlings to Drought with Different Intensities and Durations. FORESTS 2020. [DOI: 10.3390/f12010050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The root of Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) develops extremely rapidly at seedling phase and is highly sensitive to water content in soil, but its response patterns and adaptation strategies of its root to drought are little known. The aim of this study was to investigate the response of root morphology and architecture of Moso bamboo to drought at seedling phase and then to explore the drought adaptation strategies of its root. One-year-old potted seedlings of Moso bamboo were planted under three drought treatments (control, moderate drought and severe drought) for three months. Seedling growth, specific root length (SRL), root architecture (fractal dimension (FD), root branching angle (RBA) and root topological index (TI)) and non-structural carbohydrate (NSC) concentrations in roots were measured every month. The results are as follows: (i) The dry weight of root and shoot decreased significantly under drought stress. (ii) The SRL decreased under drought stress in the early duration (the first month), and then increased in the late duration (the third month). Both FD and RBA decreased, while TI and the concentrations of NSCs increased under drought stress. (iii) The NSC concentrations were positively correlated with SRL and TI, but exhibited an inverse relationship to FD and RBA. Our results indicated that Moso bamboo seedlings formed a “steeper, simpler, expensive (low SRL and high TI)” root architecture to adapt to a short-term drought (one month), and formed a “cheaper (high SRL)” root to adapt to a long-term drought (three months). Increase of NSC concentrations supported the root architecture plasticity to some extent.
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68
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Vescio R, Abenavoli MR, Sorgonà A. Single and Combined Abiotic Stress in Maize Root Morphology. PLANTS (BASEL, SWITZERLAND) 2020; 10:E5. [PMID: 33374570 PMCID: PMC7822427 DOI: 10.3390/plants10010005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/16/2020] [Accepted: 12/18/2020] [Indexed: 12/17/2022]
Abstract
Plants are continually exposed to multiple stresses, which co-occur in nature, and the net effects are frequently more nonadditive (i.e., synergistic or antagonistic), suggesting "unique" responses with respect to that of the individual stress. Further, plant stress responses are not uniform, showing a high spatial and temporal variability among and along the different organs. In this respect, the present work investigated the morphological responses of different root types (seminal, seminal lateral, primary and primary lateral) of maize plants exposed to single (drought and heat) and combined stress (drought + heat). Data were evaluated by a specific root image analysis system (WinRHIZO) and analyzed by uni- and multivariate statistical analyses. The results indicated that primary roots and their laterals were the types more sensitive to the single and combined stresses, while the seminal laterals specifically responded to the combined only. Further, antagonistic and synergistic effects were observed for the specific traits in the primary and their laterals and in the seminal lateral roots in response to the combined stress. These results suggested that the maize root system modified specific root types and traits to deal with different stressful environmental conditions, highlighting that the adaptation strategy to the combined stress may be different from that of the individual ones. The knowledge of "unique or shared" responses of plants to multiple stress can be utilized to develop varieties with broad-spectrum stress tolerance.
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Affiliation(s)
| | | | - Agostino Sorgonà
- Dipartimento Agraria, Università “Mediterranea” di Reggio Calabria, Feo di Vito, 89122 Reggio Calabria (RC), Italy; (R.V.); (M.R.A.)
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69
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Zacarias Rafael D, Arriagada O, Toro G, Mashilo J, Mora-Poblete F, Contreras-Soto RI. Plasticity of the Root System Architecture and Leaf Gas Exchange Parameters Are Important for Maintaining Bottle Gourd Responses under Water Deficit. PLANTS (BASEL, SWITZERLAND) 2020; 9:plants9121697. [PMID: 33287101 PMCID: PMC7761539 DOI: 10.3390/plants9121697] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 05/29/2023]
Abstract
The evaluation of root system architecture (RSA) development and the physiological responses of crop plants grown under water-limited conditions are of great importance. The purpose of this study was to examine the short-term variation of the morphological and physiological plasticity of Lagenaria siceraria genotypes under water deficit, evaluating the changes in the relationship between the root system architecture and leaf physiological responses. Bottle gourd genotypes were grown in rhizoboxes under well-watered and water deficit conditions. Significant genotype-water regime interactions were observed for several RSA traits and physiological parameters. Biplot analyses confirmed that the drought-tolerant genotypes (BG-48 and GC) showed a high net CO2 assimilation rate, stomatal conductance, transpiration rates with a smaller length, and a reduced root length density of second-order lateral roots, whereas the genotypes BG-67 and Osorno were identified as drought-sensitive and showed greater values for average root length and the density of second-order lateral roots. Consequently, a reduced length and density of lateral roots in bottle gourd should constitute a response to water deficit. The root traits studied here can be used to evaluate bottle gourd performance under novel water management strategies and as criteria for breeding selection.
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Affiliation(s)
| | - Osvin Arriagada
- Departamento de Ciencias Vegetales, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago 306-22, Chile;
| | - Guillermo Toro
- Plant Stress Physiology Laboratory, Centro de Estudios Avanzados en Fruticultura (CEAF), Rengo 2940000, Chile;
| | - Jacob Mashilo
- Limpopo Department of Agriculture and Rural, Bela-Bela 0480, South Africa;
| | - Freddy Mora-Poblete
- Institute of Biological Science, University of Talca, Talca 3460000, Chile; (D.Z.R.); (F.M.-P.)
| | - Rodrigo Iván Contreras-Soto
- Instituto de Ciencias Agroalimentarias, Animales y Ambientales, Universidad de O’Higgins, San Fernando 3070000, Chile
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van der Bom FJT, Williams A, Bell MJ. Root architecture for improved resource capture: trade-offs in complex environments. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:5752-5763. [PMID: 32667996 DOI: 10.1093/jxb/eraa324] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 07/10/2020] [Indexed: 05/24/2023]
Abstract
Root architecture is a promising breeding target for developing resource-efficient crops. Breeders and plant physiologists have called for root ideotypes that have narrow, deep root systems for improved water and nitrate capture, or wide, shallower root systems for better uptake of less mobile topsoil nutrients such as phosphorus. Yet evidence of relationships between root architecture and crop yield is limited. Many studies focus on the response to a single constraint, despite the fact that crops are frequently exposed to multiple soil constraints. For example, in dryland soils under no-till management, topsoil nutrient stratification is an emergent profile characteristic, leading to spatial separation of water and nutrients as the soil profile dries. This results in spatio-temporal trade-offs between efficient resource capture and pre-defined root ideotypes developed to counter a single constraint. We believe there is need to identify and better understand trade-offs involved in the efficient capture of multiple, spatially disjunct soil resources. Additionally, how these trade-offs interact with genotype (root architecture), environment (soil constraints), and management (agronomy) are critical unknowns. We argue that identifying root traits that enable efficient capture of multiple soil resources under fluctuating environmental constraints is a key step towards meeting the challenges of global food security.
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Affiliation(s)
- Frederik J T van der Bom
- School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Alwyn Williams
- School of Agriculture and Food Sciences, The University of Queensland, Gatton, QLD, Australia
| | - Michael J Bell
- School of Agriculture and Food Sciences, The University of Queensland, Gatton, QLD, Australia
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Gatton, QLD, Australia
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71
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Benny J, Marchese A, Giovino A, Marra FP, Perrone A, Caruso T, Martinelli F. Gaining Insight into Exclusive and Common Transcriptomic Features Linked to Drought and Salinity Responses across Fruit Tree Crops. PLANTS (BASEL, SWITZERLAND) 2020; 9:E1059. [PMID: 32825043 PMCID: PMC7570245 DOI: 10.3390/plants9091059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/29/2022]
Abstract
The present study aimed at identifying and mapping key genes expressed in root tissues involved in drought and salinity tolerance/resistance conserved among different fruit tree species. Twenty-six RNA-Seq samples were analyzed from six published studies in five plant species (Olea europaea, Vitis riparia Michx, Prunus mahaleb, Prunus persica, Phoenix dactylifera). This meta-analysis used a bioinformatic pipeline identifying 750 genes that were commonly modulated in three salinity studies and 683 genes that were commonly regulated among three drought studies, implying their conserved role in resistance/tolerance/response to these environmental stresses. A comparison was done on the genes that were in common among both salinity and drought resulted in 82 genes, of which 39 were commonly regulated with the same trend of expression (23 were upregulated and 16 were downregulated). Gene set enrichment and pathway analysis pointed out that pathways encoding regulation of defense response, drug transmembrane transport, and metal ion binding are general key molecular responses to these two abiotic stress responses. Furthermore, hormonal molecular crosstalk plays an essential role in the fine-tuning of plant responses to drought and salinity. Drought and salinity induced a different molecular "hormonal fingerprint". Dehydration stress specifically enhanced multiple genes responsive to abscisic acid, gibberellin, brassinosteroids, and the ethylene-activated signaling pathway. Salt stress mostly repressed genes encoding for key enzymes in signaling proteins in auxin-, gibberellin-(gibberellin 2 oxidase 8), and abscisic acid-related pathways (aldehyde oxidase 4, abscisic acid-responsive element-binding protein 3). Abiotic stress-related genes were mapped into the chromosome to identify molecular markers usable for the improvement of these complex quantitative traits. This meta-analysis identified genes that serve as potential targets to develop cultivars with enhanced drought and salinity resistance and/or tolerance across different fruit tree crops in a biotechnological sustainable way.
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Affiliation(s)
- Jubina Benny
- Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze—Ed. 4, 90128 Palermo, Italy; (J.B.); (T.C.)
| | - Annalisa Marchese
- Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze—Ed. 4, 90128 Palermo, Italy; (J.B.); (T.C.)
| | - Antonio Giovino
- Council for Agricultural Research and Economics (CREA), Research Centre for Plant Protection and Certification (CREA-DC), 90011 Bagheria, Italy;
| | - Francesco Paolo Marra
- Department of Architecture (DARCH), University of Palermo, Viale delle Scienze—Ed. 8, 90128 Palermo, Italy;
| | - Anna Perrone
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy;
| | - Tiziano Caruso
- Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze—Ed. 4, 90128 Palermo, Italy; (J.B.); (T.C.)
| | - Federico Martinelli
- Department of Biology, University of Florence, Sesto Fiorentino, 50019 Florence, Italy;
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Strock CF, Lynch JP. Root secondary growth: an unexplored component of soil resource acquisition. ANNALS OF BOTANY 2020; 126:205-218. [PMID: 32588876 PMCID: PMC7523590 DOI: 10.1093/aob/mcaa068] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Indexed: 05/06/2023]
Abstract
BACKGROUND AND AIMS Despite recent progress in elucidating the molecular basis of secondary growth (cambial growth), the functional implications of this developmental process remain poorly understood. Targeted studies exploring how abiotic and biotic factors affect this process, as well as the relevance of secondary growth to fitness of annual dicotyledonous crop species under stress, are almost entirely absent from the literature. Specifically, the physiological role of secondary growth in roots has been completely neglected yet entails a unique array of implications for plant performance that are distinct from secondary growth in shoot tissue. SCOPE Since roots are directly responsible for soil resource capture, understanding of the fitness landscape of root phenotypes is important in both basic and applied plant biology. Interactions between root secondary growth, edaphic conditions and soil resource acquisition may have significant effects on plant fitness. Our intention here is not to provide a comprehensive review of a sparse and disparate literature, but rather to highlight knowledge gaps, propose hypotheses and identify opportunities for novel and agriculturally relevant research pertaining to secondary growth of roots. This viewpoint: (1) summarizes evidence from our own studies and other published work; (2) proposes hypotheses regarding the fitness landscape of secondary growth of roots in annual dicotyledonous species for abiotic and biotic stress; and (3) highlights the importance of directing research efforts to this topic within an agricultural context. CONCLUSIONS Secondary growth of the roots of annual dicots has functional significance with regards to soil resource acquisition and transport, interactions with soil organisms and carbon sequestration. Research on these topics would contribute significantly toward understanding the agronomic value of secondary growth of roots for crop improvement.
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Affiliation(s)
- Christopher F Strock
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
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Vanhees DJ, Loades KW, Bengough AG, Mooney SJ, Lynch JP. Root anatomical traits contribute to deeper rooting of maize under compacted field conditions. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:4243-4257. [PMID: 32420593 PMCID: PMC7337194 DOI: 10.1093/jxb/eraa165] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 04/30/2020] [Indexed: 05/21/2023]
Abstract
To better understand the role of root anatomy in regulating plant adaptation to soil mechanical impedance, 12 maize lines were evaluated in two soils with and without compaction treatments under field conditions. Penetrometer resistance was 1-2 MPa greater in the surface 30 cm of the compacted plots at a water content of 17-20% (v/v). Root thickening in response to compaction varied among genotypes and was negatively associated with rooting depth at one field site under non-compacted plots. Thickening was not associated with rooting depth on compacted plots. Genotypic variation in root anatomy was related to rooting depth. Deeper-rooting plants were associated with reduced cortical cell file number in combination with greater mid cortical cell area for node 3 roots. For node 4, roots with increased aerenchyma were deeper roots. A greater influence of anatomy on rooting depth was observed for the thinner root classes. We found no evidence that root thickening is related to deeper rooting in compacted soil; however, anatomical traits are important, especially for thinner root classes.
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Affiliation(s)
- Dorien J Vanhees
- Division of Agricultural and Environment Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK
- The James Hutton Institute, Invergowrie, UK
| | | | - A Glyn Bengough
- The James Hutton Institute, Invergowrie, UK
- School of Science and Engineering, The University of Dundee, Dundee, UK
| | - Sacha J Mooney
- Division of Agricultural and Environment Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK
| | - Jonathan P Lynch
- Division of Agricultural and Environment Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK
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Bagnall GC, Koonjoo N, Altobelli SA, Conradi MS, Fukushima E, Kuethe DO, Mullet JE, Neely H, Rooney WL, Stupic KF, Weers B, Zhu B, Rosen MS, Morgan CL. Low-field magnetic resonance imaging of roots in intact clayey and silty soils. GEODERMA 2020; 370:10.1016/j.geoderma.2020.114356. [PMID: 36452276 PMCID: PMC9706682 DOI: 10.1016/j.geoderma.2020.114356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The development of a robust method to non-invasively visualize root morphology in natural soils has been hampered by the opaque, physical, and structural properties of soils. In this work we describe a novel technology, low field magnetic resonance imaging (LF-MRI), for imaging energy sorghum (Sorghum bicolor (L.) Moench) root morphology and architecture in intact soils. The use of magnetic fields much weaker than those used with traditional MRI experiments reduces the distortion due to magnetic material naturally present in agricultural soils. A laboratory based LF-MRI operating at 47 mT magnetic field strength was evaluated using two sets of soil cores: 1) soil/root cores of Weswood silt loam (Udifluventic Haplustept) and a Belk clay (Entic Hapluderts) from a conventionally tilled field, and 2) soil/root cores from rhizotrons filled with either a Houston Black (Udic Haplusterts) clay or a sandy loam purchased from a turf company. The maximum soil water nuclear magnetic resonance (NMR) relaxation time T2 (4 ms) and the typical root water relaxation time T2 (100 ms) are far enough apart to provide a unique contrast mechanism such that the soil water signal has decayed to the point of no longer being detectable during the data collection time period. 2-D MRI projection images were produced of roots with a diameter range of 1.5-2.0 mm using an image acquisition time of 15 min with a pixel resolution of 1.74 mm in four soil types. Additionally, we demonstrate the use of a data-driven machine learning reconstruction approach, Automated Transform by Manifold Approximation (AUTOMAP) to reconstruct raw data and improve the quality of the final images. The application of AUTOMAP showed a SNR (Signal to Noise Ratio) improvement of two fold on average. The use of low field MRI presented here demonstrates the possibility of applying low field MRI through intact soils to root phenotyping and agronomy to aid in understanding of root morphology and the spatial arrangement of roots in situ.
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Affiliation(s)
- G. Cody Bagnall
- Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX, USA
| | - Neha Koonjoo
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA
- Harvard Medical School, Boston, MA 02115, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | | | - Mark S. Conradi
- ABQMR, Inc. 2301 Yale Blvd SE, Suite C2, Albuquerque, NM 87106, USA
| | - Eiichi Fukushima
- ABQMR, Inc. 2301 Yale Blvd SE, Suite C2, Albuquerque, NM 87106, USA
| | - Dean O. Kuethe
- ABQMR, Inc. 2301 Yale Blvd SE, Suite C2, Albuquerque, NM 87106, USA
| | - John E. Mullet
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Haly Neely
- Department of Soil and Crop Science, Texas A&M University, College Station, TX, USA
| | - William L. Rooney
- Department of Soil and Crop Science, Texas A&M University, College Station, TX, USA
| | - Karl F. Stupic
- National Institute of Standards and Technology, Applied Physics Division, 325 Broadway, Boulder, CO 80305, USA
| | - Brock Weers
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Bo Zhu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA
- Harvard Medical School, Boston, MA 02115, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Matthew S. Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA
- Harvard Medical School, Boston, MA 02115, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
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75
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Chapman K, Ivanovici A, Taleski M, Sturrock CJ, Ng JLP, Mohd-Radzman NA, Frugier F, Bennett MJ, Mathesius U, Djordjevic MA. CEP receptor signalling controls root system architecture in Arabidopsis and Medicago. THE NEW PHYTOLOGIST 2020; 226:1809-1821. [PMID: 32048296 DOI: 10.1111/nph.16483] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 02/04/2020] [Indexed: 06/10/2023]
Abstract
Root system architecture (RSA) influences the effectiveness of resources acquisition from soils but the genetic networks that control RSA remain largely unclear. We used rhizoboxes, X-ray computed tomography, grafting, auxin transport measurements and hormone quantification to demonstrate that Arabidopsis and Medicago CEP (C-TERMINALLY ENCODED PEPTIDE)-CEP RECEPTOR signalling controls RSA, the gravitropic set-point angle (GSA) of lateral roots (LRs), auxin levels and auxin transport. We showed that soil-grown Arabidopsis and Medicago CEP receptor mutants have a narrower RSA, which results from a steeper LR GSA. Grafting showed that CEPR1 in the shoot controls GSA. CEP receptor mutants exhibited an increase in rootward auxin transport and elevated shoot auxin levels. Consistently, the application of auxin to wild-type shoots induced a steeper GSA and auxin transport inhibitors counteracted the CEP receptor mutant's steep GSA phenotype. Concordantly, CEP peptides increased GSA and inhibited rootward auxin transport in wild-type but not in CEP receptor mutants. The results indicated that CEP-CEP receptor-dependent signalling outputs in Arabidopsis and Medicago control overall RSA, LR GSA, shoot auxin levels and rootward auxin transport. We propose that manipulating CEP signalling strength or CEP receptor downstream targets may provide means to alter RSA.
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Affiliation(s)
- Kelly Chapman
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Ariel Ivanovici
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Michael Taleski
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Craig J Sturrock
- The Hounsfield Facility, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Jason L P Ng
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Nadiatul A Mohd-Radzman
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Florian Frugier
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, Université, Paris Sud, Université, Paris Diderot, INRA, Univ d'Evry, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Malcolm J Bennett
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Ulrike Mathesius
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Michael A Djordjevic
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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76
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Schneider HM, Klein SP, Hanlon MT, Nord EA, Kaeppler S, Brown KM, Warry A, Bhosale R, Lynch JP. Genetic control of root architectural plasticity in maize. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3185-3197. [PMID: 32080722 PMCID: PMC7260711 DOI: 10.1093/jxb/eraa084] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/20/2020] [Indexed: 05/05/2023]
Abstract
Root phenotypes regulate soil resource acquisition; however, their genetic control and phenotypic plasticity are poorly understood. We hypothesized that the responses of root architectural phenes to water deficit (stress plasticity) and different environments (environmental plasticity) are under genetic control and that these loci are distinct. Root architectural phenes were phenotyped in the field using a large maize association panel with and without water deficit stress for three seasons in Arizona and without water deficit stress for four seasons in South Africa. All root phenes were plastic and varied in their plastic response. We identified candidate genes associated with stress and environmental plasticity and candidate genes associated with phenes in well-watered conditions in South Africa and in well-watered and water-stress conditions in Arizona. Few candidate genes for plasticity overlapped with those for phenes expressed under each condition. Our results suggest that phenotypic plasticity is highly quantitative, and plasticity loci are distinct from loci that control phene expression in stress and non-stress, which poses a challenge for breeding programs. To make these loci more accessible to the wider research community, we developed a public online resource that will allow for further experimental validation towards understanding the genetic control underlying phenotypic plasticity.
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Affiliation(s)
- Hannah M Schneider
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Stephanie P Klein
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Meredith T Hanlon
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Eric A Nord
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Shawn Kaeppler
- Department of Agronomy, University of Wisconsin, Madison, WI, USA
| | - Kathleen M Brown
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Andrew Warry
- Advanced Data Analysis Centre, University of Nottingham, Nottingham, UK
| | - Rahul Bhosale
- Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, UK
| | - Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
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77
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Schneider HM, Lynch JP. Should Root Plasticity Be a Crop Breeding Target? FRONTIERS IN PLANT SCIENCE 2020; 11:546. [PMID: 32499798 PMCID: PMC7243933 DOI: 10.3389/fpls.2020.00546] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/09/2020] [Indexed: 05/18/2023]
Abstract
Root phenotypic plasticity has been proposed as a target for the development of more productive crops in variable environments. However, the plasticity of root anatomical and architectural responses to environmental cues is highly complex, and the consequences of these responses for plant fitness are poorly understood. We propose that root phenotypic plasticity may be beneficial in natural or low-input systems in which the availability of soil resources is spatiotemporally dynamic. Crop ancestors and landraces were selected with multiple stresses, competition, significant root loss and heterogenous resource distribution which favored plasticity in response to resource availability. However, in high-input agroecosystems, the value of phenotypic plasticity is unclear, since human management has removed many of these constraints to root function. Further research is needed to understand the fitness landscape of plastic responses including understanding the value of plasticity in different environments, environmental signals that induce plastic responses, and the genetic architecture of plasticity before it is widely adopted in breeding programs. Phenotypic plasticity has many potential ecological, and physiological benefits, but its costs and adaptive value in high-input agricultural systems is poorly understood and merits further research.
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Affiliation(s)
| | - Jonathan P. Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA, United States
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78
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Guo J, Li C, Zhang X, Li Y, Zhang D, Shi Y, Song Y, Li Y, Yang D, Wang T. Transcriptome and GWAS analyses reveal candidate gene for seminal root length of maize seedlings under drought stress. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 292:110380. [PMID: 32005385 DOI: 10.1016/j.plantsci.2019.110380] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 12/12/2019] [Accepted: 12/14/2019] [Indexed: 05/21/2023]
Abstract
Water deficits are a major constraint on maize growth and yield, and deep roots are one of the major mechanisms of drought tolerance. In this study, four root and shoot traits were evaluated within an association panel consisting of 209 diverse maize accessions under well-watered (WW) and water-stressed (WS) conditions. A significant positive correlation was observed between seminal root length (SRL) under WS treatment and the drought tolerance index (DI) of maize seedlings. The transcriptome profiles of maize seminal roots were compared between four drought-tolerant lines and four drought-sensitive lines under both water conditions to identify genes associated with the drought stress response. After drought stress, 343 and 177 common differentially expressed genes (DEGs) were identified in the drought-tolerant group and drought-sensitive group, respectively. In parallel, a coexpression network underlying SRL was constructed on the basis of transcriptome data, and 10 hub genes involved in two significant associated modules were identified. Additionally, a genome-wide association study (GWAS) of the SRL revealed 62 loci for the two water treatments. By integrating the results of the GWAS, the common DEGs and the coexpression network analysis, 7 promising candidate genes were prioritized for further research. Together, our results provide a foundation for the enhanced understanding of seminal root changes in response to drought stress in maize.
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Affiliation(s)
- Jian Guo
- College of Agriculture, Northeast Agricultural University, Harbin, China
| | - Chunhui Li
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
| | | | - Yongxiang Li
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Dengfeng Zhang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yunsu Shi
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yanchun Song
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yu Li
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Deguang Yang
- College of Agriculture, Northeast Agricultural University, Harbin, China.
| | - Tianyu Wang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
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79
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Schneider HM, Klein SP, Hanlon MT, Kaeppler S, Brown KM, Lynch JP. Genetic control of root anatomical plasticity in maize. THE PLANT GENOME 2020; 13:e20003. [PMID: 33016634 DOI: 10.1002/tpg2.20003] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 11/01/2019] [Indexed: 05/06/2023]
Abstract
Root anatomical phenes have important roles in soil resource capture and plant performance; however, their phenotypic plasticity and genetic architecture is poorly understood. We hypothesized that (a) the responses of root anatomical phenes to water deficit (stress plasticity) and different environmental conditions (environmental plasticity) are genetically controlled and (b) stress and environmental plasticity are associated with different genetic loci than those controlling the expression of phenes under water-stress and well-watered conditions. Root anatomy was phenotyped in a large maize (Zea mays L.) association panel in the field with and without water deficit stress in Arizona and without water deficit stress in South Africa. Anatomical phenes displayed stress and environmental plasticity; many phenotypic responses to water deficit were adaptive, and the magnitude of response varied by genotype. We identified 57 candidate genes associated with stress and environmental plasticity and 64 candidate genes associated with phenes under well-watered and water-stress conditions in Arizona and under well-watered conditions in South Africa. Four candidate genes co-localized between plasticity groups or for phenes expressed under each condition. The genetic architecture of phenotypic plasticity is highly quantitative, and many distinct genes control plasticity in response to water deficit and different environments, which poses a challenge for breeding programs.
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Affiliation(s)
- Hannah M Schneider
- Dep. of Plant Science, Pennsylvania State Univ., University Park, PA, 16802, USA
| | - Stephanie P Klein
- Dep. of Plant Science, Pennsylvania State Univ., University Park, PA, 16802, USA
| | - Meredith T Hanlon
- Dep. of Plant Science, Pennsylvania State Univ., University Park, PA, 16802, USA
| | - Shawn Kaeppler
- Dep. of Agronomy, Univ. of Wisconsin, Madison, WI, 53706, USA
| | - Kathleen M Brown
- Dep. of Plant Science, Pennsylvania State Univ., University Park, PA, 16802, USA
| | - Jonathan P Lynch
- Dep. of Plant Science, Pennsylvania State Univ., University Park, PA, 16802, USA
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80
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Yang JT, Schneider HM, Brown KM, Lynch JP. Genotypic variation and nitrogen stress effects on root anatomy in maize are node specific. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5311-5325. [PMID: 31231768 PMCID: PMC6793441 DOI: 10.1093/jxb/erz293] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 06/11/2019] [Indexed: 05/18/2023]
Abstract
Root phenotypes that improve nitrogen acquisition are avenues for crop improvement. Root anatomy affects resource capture, metabolic cost, hydraulic conductance, anchorage, and soil penetration. Cereal root phenotyping has centered on primary, seminal, and early nodal roots, yet critical nitrogen uptake occurs when the nodal root system is well developed. This study examined root anatomy across nodes in field-grown maize (Zea mays L.) hybrid and inbred lines under high and low nitrogen regimes. Genotypes with high nitrogen use efficiency (NUE) had larger root diameter and less cortical aerenchyma across nodes under stress than genotypes with lower NUE. Anatomical phenes displayed slightly hyperallometric relationships to shoot biomass. Anatomical plasticity varied across genotypes; most genotypes decreased root diameter under stress when averaged across nodes. Cortex, stele, total metaxylem vessel areas, and cortical cell file and metaxylem vessel numbers scaled strongly with root diameter across nodes. Within nodes, metaxylem vessel size and cortical cell size were correlated, and root anatomical phenotypes in the first and second nodes were not representative of subsequent nodes. Node, genotype, and nitrogen treatment affect root anatomy. Understanding nodal variation in root phenes will enable the development of plants that are adapted to low nitrogen conditions.
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Affiliation(s)
- Jennifer T Yang
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
- Present address: Wellesley College, Wellesley, MA 02481, USA
| | - Hannah M Schneider
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Kathleen M Brown
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
- Correspondence:
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81
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Guo H, York LM. Maize with fewer nodal roots allocates mass to more lateral and deep roots that improve nitrogen uptake and shoot growth. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5299-5309. [PMID: 31145788 PMCID: PMC6793442 DOI: 10.1093/jxb/erz258] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/23/2019] [Indexed: 05/19/2023]
Abstract
Simulations indicated that reduced nodal root (NR) number (NRN) was promising for maize breeding, and were partially confirmed by relying on variation in NRN among inbreds. Using maize inbred line B73, experiments were conducted in hydroponics and tall mesocosms containing solid media with treatments involving no NR excision (0% NRE) or excising either 33% or 67% of the NRs as they emerged under high or low levels of nitrogen (N). Reduced NRN was hypothesized to increase elongation of all remaining root classes, N acquisition under low N, and shoot mass. Plants with 67% NRE had 12% and 19% less root mass fraction, 61% and 91% greater lateral to axial root length ratio regardless of N levels, and 61% and 182% greater biomass of embryonic roots under low N, compared with 0% NRE for hydroponics and mesocosms studies, respectively. Under low N in mesocosms, plants with 67% NRE had 52% greater shoot biomass, 450% greater root length at depth, and 232% greater deep-injected 15N content in the shoot relative to 0% NRE. These results reveal the mechanism by which plants with fewer NRs increase N capture and shoot mass by reallocation of biomass to lateral roots, embryonic roots, and first whorl NRs that increases foraging efficiency in solid media.
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Affiliation(s)
- Haichao Guo
- Noble Research Institute, LLC, Ardmore, OK, USA
| | - Larry M York
- Noble Research Institute, LLC, Ardmore, OK, USA
- Correspondence:
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82
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Abstract
Roots provide the primary mechanism that plants use to absorb water and nutrients from their environment. These functions are dependent on developmental mechanisms that direct root growth and branching into regions of soil where these resources are relatively abundant. Water is the most limiting factor for plant growth, and its availability is determined by the weather, soil structure, and salinity. In this review, we define the developmental pathways that regulate the direction of growth and branching pattern of the root system, which together determine the expanse of soil from which a plant can access water. The ability of plants to regulate development in response to the spatial distribution of water is a focus of many recent studies and provides a model for understanding how biological systems utilize positional cues to affect signaling and morphogenesis. A better understanding of these processes will inform approaches to improve crop water use efficiency to more sustainably feed a growing population.
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Affiliation(s)
- José R. Dinneny
- Department of Biology, Stanford University, Stanford, California 94305, USA
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83
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Muller B, Guédon Y, Passot S, Lobet G, Nacry P, Pagès L, Wissuwa M, Draye X. Lateral Roots: Random Diversity in Adversity. TRENDS IN PLANT SCIENCE 2019; 24:810-825. [PMID: 31320193 DOI: 10.1016/j.tplants.2019.05.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 05/24/2019] [Accepted: 05/31/2019] [Indexed: 06/10/2023]
Abstract
Lateral roots are essential for soil foraging and uptake of minerals and water. They feature a large morphological diversity that results from divergent primordia or root growth and development patterns. Besides a structured diversity, resulting from the hierarchical and developmental organization of root systems, there exists a random diversity, occurring between roots of similar age, of the same hierarchical order, and exposed to uniform conditions. The physiological bases and functional consequences of this random diversity are largely ignored. Here we review the evidence for such random diversity throughout the plant kingdom, present innovative approaches based on statistical modeling to account for such diversity, and set the list of its potential benefits in front of a variable and unpredictable soil environment.
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Affiliation(s)
- Bertrand Muller
- INRA, Supagro, Université Montpellier, UMR 759 Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 34060 Montpellier, France.
| | - Yann Guédon
- CIRAD, Université Montpellier, UMR 1334 Adaptation Génétique et Amélioration des Plantes, 34398, Montpellier, France
| | - Sixtine Passot
- Université catholique de Louvain, Earth and Life Institute, 1348 Louvain-la-Neuve, Belgium
| | - Guillaume Lobet
- Université catholique de Louvain, Earth and Life Institute, 1348 Louvain-la-Neuve, Belgium; Forschungszentrum Juelich GmbH, IBG3 Agrosphere, 52428 Juelich, Germany
| | - Philippe Nacry
- INRA, Supagro, CNRS, Université Montpellier, UMR 5004 Biochimie et Physiologie Moléculaire des Plantes, 340660 Montpellier, France
| | - Loïc Pagès
- INRA, UR, 1115 Plantes et Systèmes de culture Horticoles, Site Agroparc, 84914 Avignon, France
| | - Matthias Wissuwa
- Japan International Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki, 305-8686, Japan
| | - Xavier Draye
- Université catholique de Louvain, Earth and Life Institute, 1348 Louvain-la-Neuve, Belgium.
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84
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Gonin M, Bergougnoux V, Nguyen TD, Gantet P, Champion A. What Makes Adventitious Roots? PLANTS (BASEL, SWITZERLAND) 2019; 8:E240. [PMID: 31336687 PMCID: PMC6681363 DOI: 10.3390/plants8070240] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/08/2019] [Accepted: 07/17/2019] [Indexed: 12/28/2022]
Abstract
The spermatophyte root system is composed of a primary root that develops from an embryonically formed root meristem, and of different post-embryonic root types: lateral and adventitious roots. Adventitious roots, arising from the stem of the plants, are the main component of the mature root system of many plants. Their development can also be induced in response to adverse environmental conditions or stresses. Here, in this review, we report on the morphological and functional diversity of adventitious roots and their origin. The hormonal and molecular regulation of the constitutive and inducible adventitious root initiation and development is discussed. Recent data confirmed the crucial role of the auxin/cytokinin balance in adventitious rooting. Nevertheless, other hormones must be considered. At the genetic level, adventitious root formation integrates the transduction of external signals, as well as a core auxin-regulated developmental pathway that is shared with lateral root formation. The knowledge acquired from adventitious root development opens new perspectives to improve micropropagation by cutting in recalcitrant species, root system architecture of crops such as cereals, and to understand how plants adapted during evolution to the terrestrial environment by producing different post-embryonic root types.
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Affiliation(s)
- Mathieu Gonin
- Université de Montpellier, IRD, UMR DIADE, 34,394 Montpellier, France
| | - Véronique Bergougnoux
- Department of Molecular Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
| | - Thu D Nguyen
- Department of Molecular Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
| | - Pascal Gantet
- Université de Montpellier, IRD, UMR DIADE, 34,394 Montpellier, France
- Department of Molecular Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
| | - Antony Champion
- Université de Montpellier, IRD, UMR DIADE, 34,394 Montpellier, France
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85
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Fromm H. Root Plasticity in the Pursuit of Water. PLANTS (BASEL, SWITZERLAND) 2019; 8:E236. [PMID: 31336579 PMCID: PMC6681320 DOI: 10.3390/plants8070236] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/19/2019] [Accepted: 07/19/2019] [Indexed: 01/22/2023]
Abstract
One of the greatest challenges of terrestrial vegetation is to acquire water through soil-grown roots. Owing to the scarcity of high-quality water in the soil and the environment's spatial heterogeneity and temporal variability, ranging from extreme flooding to drought, roots have evolutionarily acquired tremendous plasticity regarding their geometric arrangement of individual roots and their three-dimensional organization within the soil. Water deficiency has also become an increasing threat to agriculture and dryland ecosystems due to climate change. As a result, roots have become important targets for genetic selection and modification in an effort to improve crop resilience under water-limiting conditions. This review addresses root plasticity from different angles: Their structures and geometry in response to the environment, potential genetic control of root traits suitable for water-limiting conditions, and contemporary and future studies of the principles underlying root plasticity post-Darwin's 'root-brain' hypothesis. Our increasing knowledge of different disciplines of plant sciences and agriculture should contribute to a sustainable management of natural and agricultural ecosystems for the future of mankind.
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Affiliation(s)
- Hillel Fromm
- School of Plant Sciences and Food Security, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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86
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Lynch JP. Root phenotypes for improved nutrient capture: an underexploited opportunity for global agriculture. THE NEW PHYTOLOGIST 2019; 223:548-564. [PMID: 30746704 DOI: 10.1111/nph.15738] [Citation(s) in RCA: 203] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Accepted: 01/29/2019] [Indexed: 05/22/2023]
Abstract
Nutrient-efficient crops are a solution to the two grand challenges of modern agriculture: improving food security while reducing environmental impacts. The primary challenges are (1) nitrogen (N) and phosphorus (P) efficiency; (2) potassium (K), calcium (Ca), and magnesium (Mg) efficiency for acid soils; and (3) iron (Fe) and zinc (Zn) efficiency for alkaline soils. Root phenotypes are promising breeding targets for each of these. The Topsoil Foraging ideotype is beneficial for P capture and should also be useful for capture of K, Ca, and Mg in acid soils. The Steep, Cheap, and Deep ideotype for subsoil foraging is beneficial for N and water capture. Fe and Zn capture can be improved by targeting mechanisms of metal mobilization in the rhizosphere. Root hairs and phenes that reduce the metabolic cost of soil exploration should be prioritized in breeding programs. Nutrient-efficient crops should provide benefits at all input levels. Although our current understanding is sufficient to deploy root phenotypes for improved nutrient capture in crop breeding, this complex topic does not receive the resources it merits in either applied or basic plant biology. Renewed emphasis on these topics is needed in order to develop the nutrient-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
- School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire, LE12 5RD, UK
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87
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Fried HG, Narayanan S, Fallen B. Evaluation of soybean [Glycine max (L.) Merr.] genotypes for yield, water use efficiency, and root traits. PLoS One 2019; 14:e0212700. [PMID: 30794664 PMCID: PMC6386299 DOI: 10.1371/journal.pone.0212700] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 02/07/2019] [Indexed: 11/19/2022] Open
Abstract
Drought stress has been identified as the major environmental factor limiting soybean [Glycine max (L.) Merr.] yield worldwide. Current breeding efforts in soybean largely focus on identifying genotypes with high seed yield and drought tolerance. Water use efficiency (WUE) that results in greater yield per unit rainfall is an important parameter in determining crop yields in many production systems, and is often related with crop drought tolerance. Even though roots are major plant organs that perceive and respond to drought stress, their utility in improving soybean yield and WUE under different environmental and management conditions are largely unclear. The objectives of this research was to evaluate soybean cultivars and breeding and germplasm lines for yield, WUE, root penetrability of hardpan, and root morphology. Field experiments were conducted at two locations in South Carolina (southeastern United States) during the 2017 cropping season to test the genotypes for yield and root morphology under irrigated and non-irrigated conditions. Two independent controlled-environmental experiments were conducted to test the genotypes for WUE and root penetrability of synthetic hardpans. The slow wilting lines NTCPR94-5157 and N09-13890 had equal or greater yield than the checks- cultivar NC-Raleigh and the elite South Carolina breeding line SC07-1518RR, under irrigated and non-irrigated conditions. The high yielding genotypes NTCPR94-5157, N09-13890, and SC07-1518RR exhibited root parsimony (reduced root development). This supported the recent hypothesis in literature that root parsimony would have adaptational advantage to improve yield under high input field conditions. The high yielding genotypes NTCPR94-5157, N09-13890, NC-Raleigh, and SC07-1518RR and a cultivar Boggs (intermediate in yield) possessed high WUE and had increased root penetrability of hardpans. These genotypes offer useful genetic materials for soybean breeding programs for improving yield, drought tolerance, and/or hardpan penetrability.
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Affiliation(s)
- Harrison Gregory Fried
- Department of Plant and Environmental Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Sruthi Narayanan
- Department of Plant and Environmental Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Benjamin Fallen
- Pee Dee Research and Education Center, Clemson University, Florence, South Carolina, United States of America
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88
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Hazman M, Brown KM. Progressive drought alters architectural and anatomical traits of rice roots. RICE (NEW YORK, N.Y.) 2018; 11:62. [PMID: 30511228 PMCID: PMC6277260 DOI: 10.1186/s12284-018-0252-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 10/24/2018] [Indexed: 05/18/2023]
Abstract
BACKGROUND Root architectural and anatomical phenotypes are important for adaptation to drought. Many rice-growing regions face increasing water scarcity. This study describes drought responses of 11 Egyptian rice cultivars with emphasis on plastic root responses that may enhance drought adaptation. RESULTS Eleven Egyptian rice cultivars were phenotyped for root architectural and anatomical traits after 6 weeks growth in soil mesocosms under well-watered conditions. Four of these cultivars were more intensively phenotyped under progressive drought stress in mesocosms, using a system where more moisture was available at depth than near the surface. In response to drought stress, all cultivars significantly reduced nodal root number while increasing large lateral root branching density and total lateral root length in the deepest portions of the mesocosm, where moisture was available. Nodal root cross-sectional area, but not stele area, was reduced by drought stress, especially in the basal segments of the root, and the number of late metaxylem vessels was reduced in only one cultivar. Alterations in deposition of lignin were detected by UV illumination from laser ablation tomography, enhanced by digital staining, and confirmed with standard histochemical methods. In well-watered plants, the sclerenchyma and endodermis were heavily lignified, and lignin was also visible throughout the epidermis and cortex. Under drought stress, very little lignin was detected in the outer cell layers and none in the cortex of nodal roots, but lignin deposition was enhanced in the stele. Root anatomical phenes, including cross-section area and metaxylem vessel number and lignin deposition varied dramatically along large lateral root axes under drought stress, with increasing diameter and less lignification of the stele in successive samples taken from the base to the root apex. CONCLUSIONS Root architectural and anatomical traits varied significantly among a set of Egyptian cultivars. Most traits were plastic, i.e. changed significantly with drought treatment, and, in many cases, plasticity was cultivar-dependent. These phenotypic alterations may function to enhance water uptake efficiency. Increased large lateral root branching in the deep soil should maintain water acquisition, while water transport during drought should be secured with a more extensively lignified stele.
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Affiliation(s)
- Mohamed Hazman
- Department of Plant Science, The Pennsylvania State University, 102 Tyson Building, University Park, University Park, PA, 16802-4200, USA
- Agricultural Genetic Engineering Research Institute (AGERI), Agricultural Research Centre (ARC), 9 Gamma St., Giza, 12619, Egypt
| | - Kathleen M Brown
- Department of Plant Science, The Pennsylvania State University, 102 Tyson Building, University Park, University Park, PA, 16802-4200, USA.
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89
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Del Bianco M, Kepinski S. Building a future with root architecture. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:5319-5323. [PMID: 30445468 PMCID: PMC6255693 DOI: 10.1093/jxb/ery390] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Affiliation(s)
- Marta Del Bianco
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Stefan Kepinski
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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90
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Fry EL, Evans AL, Sturrock CJ, Bullock JM, Bardgett RD. Root architecture governs plasticity in response to drought. PLANT AND SOIL 2018; 433:189-200. [PMID: 30930495 PMCID: PMC6406839 DOI: 10.1007/s11104-018-3824-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 09/17/2018] [Indexed: 05/13/2023]
Abstract
AIMS Root characteristics are important for predicting plant and ecosystem responses to resource scarcity. Simple, categorical traits for roots could be broadly applied to ecosystem function and restoration experiments, but they need to be evaluated for their role and behaviour under various stresses, including water limitation. We hypothesised that more complex root architectures allow more plastic responses to limited water than do tap roots. METHODS We carried out two greenhouse experiments: one with a range of grassland plant species; the other with only species of Asteraceae to test the responsiveness of root architectural classes to location of limited water in the soil column. Using trait screening techniques and X-ray tomography, we measured the plasticity of the roots in response to water location. RESULTS Plasticity of root biomass was lowest in tap rooted species, while fibrous and rhizomatous roots allocated biomass preferentially to where the soil was wettest. X-ray tomography indicated that root morphology was least plastic in rhizomatous species. CONCLUSIONS Our results provide a starting point to effective categorisation of plants in terms of rooting architecture that could aid in understanding drought tolerance of grassland species. They also demonstrate the utility of X-ray tomography in root analyses.
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Affiliation(s)
- Ellen L. Fry
- School of Earth and Environmental Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester, M13 9PT UK
| | - Amy L. Evans
- School of Earth and Environmental Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester, M13 9PT UK
| | - Craig J. Sturrock
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD UK
| | - James M. Bullock
- NERC Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB UK
| | - Richard D. Bardgett
- School of Earth and Environmental Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester, M13 9PT UK
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91
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Varshney RK, Tuberosa R, Tardieu F. Progress in understanding drought tolerance: from alleles to cropping systems. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:3175-3179. [PMID: 29878257 PMCID: PMC5991209 DOI: 10.1093/jxb/ery187] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- Rajeev K Varshney
- Center of Excellence in Genomics & Systems Biology (CEGSB), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India
| | - Roberto Tuberosa
- Department of Agricultural and Food Sciences, University of Bologna, Italy
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