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Bending GD, Newman A, Picot E, Mushinski RM, Jones DL, Carré IA. Diurnal Rhythmicity in the Rhizosphere Microbiome-Mechanistic Insights and Significance for Rhizosphere Function. PLANT, CELL & ENVIRONMENT 2025; 48:2040-2052. [PMID: 39552493 PMCID: PMC11788953 DOI: 10.1111/pce.15283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 10/30/2024] [Accepted: 11/02/2024] [Indexed: 11/19/2024]
Abstract
The rhizosphere is a key interface between plants, microbes and the soil which influences plant health and nutrition and modulates terrestrial biogeochemical cycling. Recent research has shown that the rhizosphere environment is far more dynamic than previously recognised, with evidence emerging for diurnal rhythmicity in rhizosphere chemistry and microbial community composition. This rhythmicity is in part linked to the host plant's circadian rhythm, although some heterotrophic rhizosphere bacteria and fungi may also possess intrinsic rhythmicity. We review the evidence for diurnal rhythmicity in rhizosphere microbial communities and its link to the plant circadian clock. Factors which may drive microbial rhythmicity are discussed, including diurnal change in root exudate flux and composition, rhizosphere physico-chemical properties and plant immunity. Microbial processes which could contribute to community rhythmicity are considered, including self-sustained microbial rhythms, bacterial movement into and out of the rhizosphere, and microbe-microbe interactions. We also consider evidence that changes in microbial composition mediated by the plant circadian clock may affect microbial function and its significance for plant health and broader soil biogeochemical cycling processes. We identify key knowledge gaps and approaches which could help to resolve the spatial and temporal variation and functional significance of rhizosphere microbial rhythmicity. This includes unravelling the factors which determine the oscillation of microbial activity, growth and death, and cross-talk with the host over diurnal time frames. We conclude that diurnal rhythmicity is an inherent characteristic of the rhizosphere and that temporal factors should be considered and reported in rhizosphere studies.
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Affiliation(s)
| | - Amy Newman
- School of Life SciencesUniversity of WarwickCoventryUK
| | - Emma Picot
- School of Life SciencesUniversity of WarwickCoventryUK
| | | | - Davey L. Jones
- School of Environmental and Natural SciencesBangor UniversityBangorUK
- Food Futures InstituteMurdoch UniversityPerthWAAustralia
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Minorsky PV. The "plant neurobiology" revolution. PLANT SIGNALING & BEHAVIOR 2024; 19:2345413. [PMID: 38709727 PMCID: PMC11085955 DOI: 10.1080/15592324.2024.2345413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/10/2024] [Indexed: 05/08/2024]
Abstract
The 21st-century "plant neurobiology" movement is an amalgam of scholars interested in how "neural processes", broadly defined, lead to changes in plant behavior. Integral to the movement (now called plant behavioral biology) is a triad of historically marginalized subdisciplines, namely plant ethology, whole plant electrophysiology and plant comparative psychology, that set plant neurobiology apart from the mainstream. A central tenet held by these "triad disciplines" is that plants are exquisitely sensitive to environmental perturbations and that destructive experimental manipulations rapidly and profoundly affect plant function. Since destructive measurements have been the norm in plant physiology, much of our "textbook knowledge" concerning plant physiology is unrelated to normal plant function. As such, scientists in the triad disciplines favor a more natural and holistic approach toward understanding plant function. By examining the history, philosophy, sociology and psychology of the triad disciplines, this paper refutes in eight ways the criticism that plant neurobiology presents nothing new, and that the topics of plant neurobiology fall squarely under the purview of mainstream plant physiology. It is argued that although the triad disciplines and mainstream plant physiology share the common goal of understanding plant function, they are distinct in having their own intellectual histories and epistemologies.
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Affiliation(s)
- Peter V. Minorsky
- Department of Natural Sciences, Mercy University, Dobbs Ferry, NY, USA
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Nidhi, Kumar P, Pathania D, Thakur S, Sharma M. Environment-mediated mutagenetic interference on genetic stabilization and circadian rhythm in plants. Cell Mol Life Sci 2022; 79:358. [PMID: 35687153 PMCID: PMC11072124 DOI: 10.1007/s00018-022-04368-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/21/2022] [Accepted: 05/07/2022] [Indexed: 12/29/2022]
Abstract
Many mortal organisms on this planet have developed the potential to merge all internal as well as external environmental cues to regulate various processes running inside organisms and in turn make them adaptive to the environment through the circadian clock. This moving rotator controls processes like activation of hormonal, metabolic, or defense pathways, initiation of flowering at an accurate period, and developmental processes in plants to ensure their stability in the environment. All these processes that are under the control of this rotating wheel can be changed either by external environmental factors or by an unpredictable phenomenon called mutation that can be generated by either physical mutagens, chemical mutagens, or by internal genetic interruption during metabolic processes, which alters normal functionality of organisms like innate immune responses, entrainment of the clock, biomass reduction, chlorophyll formation, and hormonal signaling, despite its fewer positive roles in plants like changing plant type, loss of vernalization treatment to make them survivable in different latitudes, and defense responses during stress. In addition, with mutation, overexpression of gene components sometimes supresses mutation effect and promote normal circadian genes abundance in the cell, while sometimes it affects circadian functionality by generating arrhythmicity and shows that not only mutation but overexpression also effects normal functional activities of plant. Therefore, this review mainly summarizes the role of each circadian clock genes in regulating rhythmicity, and shows that how circadian outputs are controlled by mutations as well as overexpression phenomenon.
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Affiliation(s)
- Nidhi
- School of Biological and Environmental Sciences, Shoolini University of Biotechnology and Management Sciences, Solan, 173212, India
| | - Pradeep Kumar
- Central University of Himachal Pradesh, Dharmshala, India
| | - Diksha Pathania
- School of Biological and Environmental Sciences, Shoolini University of Biotechnology and Management Sciences, Solan, 173212, India
| | - Sourbh Thakur
- Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Gliwice, Poland
| | - Mamta Sharma
- School of Biological and Environmental Sciences, Shoolini University of Biotechnology and Management Sciences, Solan, 173212, India.
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Gaggion N, Ariel F, Daric V, Lambert É, Legendre S, Roulé T, Camoirano A, Milone DH, Crespi M, Blein T, Ferrante E. ChronoRoot: High-throughput phenotyping by deep segmentation networks reveals novel temporal parameters of plant root system architecture. Gigascience 2021; 10:giab052. [PMID: 34282452 PMCID: PMC8290196 DOI: 10.1093/gigascience/giab052] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 06/07/2021] [Accepted: 06/25/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Deep learning methods have outperformed previous techniques in most computer vision tasks, including image-based plant phenotyping. However, massive data collection of root traits and the development of associated artificial intelligence approaches have been hampered by the inaccessibility of the rhizosphere. Here we present ChronoRoot, a system that combines 3D-printed open-hardware with deep segmentation networks for high temporal resolution phenotyping of plant roots in agarized medium. RESULTS We developed a novel deep learning-based root extraction method that leverages the latest advances in convolutional neural networks for image segmentation and incorporates temporal consistency into the root system architecture reconstruction process. Automatic extraction of phenotypic parameters from sequences of images allowed a comprehensive characterization of the root system growth dynamics. Furthermore, novel time-associated parameters emerged from the analysis of spectral features derived from temporal signals. CONCLUSIONS Our work shows that the combination of machine intelligence methods and a 3D-printed device expands the possibilities of root high-throughput phenotyping for genetics and natural variation studies, as well as the screening of clock-related mutants, revealing novel root traits.
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Affiliation(s)
- Nicolás Gaggion
- Research Institute for Signals, Systems and Computational Intelligence (sinc(i)), CONICET, FICH, Universidad Nacional del Litoral, Ciudad Universitaria UNL, Santa Fe, Argentina
| | - Federico Ariel
- Instituto de Agrobiotecnología del Litoral (IAL), CONICET, FBCB, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, Santa Fe, Argentina
| | - Vladimir Daric
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, University Paris-Saclay and University of Paris Bâtiment 630, 91192 Gif sur Yvette, France
| | - Éric Lambert
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, University Paris-Saclay and University of Paris Bâtiment 630, 91192 Gif sur Yvette, France
| | - Simon Legendre
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, University Paris-Saclay and University of Paris Bâtiment 630, 91192 Gif sur Yvette, France
| | - Thomas Roulé
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, University Paris-Saclay and University of Paris Bâtiment 630, 91192 Gif sur Yvette, France
| | - Alejandra Camoirano
- Instituto de Agrobiotecnología del Litoral (IAL), CONICET, FBCB, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, Santa Fe, Argentina
| | - Diego H Milone
- Research Institute for Signals, Systems and Computational Intelligence (sinc(i)), CONICET, FICH, Universidad Nacional del Litoral, Ciudad Universitaria UNL, Santa Fe, Argentina
| | - Martin Crespi
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, University Paris-Saclay and University of Paris Bâtiment 630, 91192 Gif sur Yvette, France
| | - Thomas Blein
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, University Paris-Saclay and University of Paris Bâtiment 630, 91192 Gif sur Yvette, France
| | - Enzo Ferrante
- Research Institute for Signals, Systems and Computational Intelligence (sinc(i)), CONICET, FICH, Universidad Nacional del Litoral, Ciudad Universitaria UNL, Santa Fe, Argentina
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Lee HG, Seo PJ. Dependence and independence of the root clock on the shoot clock in Arabidopsis. Genes Genomics 2018; 40:1063-1068. [DOI: 10.1007/s13258-018-0710-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 05/31/2018] [Indexed: 01/16/2023]
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Fu J, Yang L, Dai S. Conservation of Arabidopsis thaliana circadian clock genes in Chrysanthemum lavandulifolium. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 80:337-347. [PMID: 24844451 DOI: 10.1016/j.plaphy.2014.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/05/2014] [Indexed: 06/03/2023]
Abstract
In Arabidopsis, circadian clock genes play important roles in photoperiod pathway by regulating the daytime expression of CONSTANS (CO), but related reports for chrysanthemum are notably limited. In this study, we isolated eleven circadian clock genes, which lie in the three interconnected negative and positive feedback loops in a wild diploid chrysanthemum, Chrysanthemum lavandulifolium. With the exception of ClELF3, ClPRR1 and ClPRR73, most of the circadian clock genes are expressed more highly in leaves than in other tested tissues. The diurnal rhythms of these circadian clock genes are similar to those of their homologs in Arabidopsis. ClELF3 and ClZTL are constitutively expressed at all time points in both assessed photoperiods. The expression succession from morning to night of the PSEUDO RESPONSE REGULATOR (PRR) gene family occurs in the order ClPRR73/ClPRR37, ClPRR5, and then ClPRR1. ClLHY is expressed during the dawn period, and ClGIs is expressed during the dusk period. The peak expression levels of ClFKF1 and ClGIs are synchronous in the inductive photoperiod. However, in the non-inductive night break (NB) condition or non-24 h photoperiod, the peak expression level of ClFKF1 is significantly changed, indicating that ClFKF1 itself or the synchronous expression of ClFKF1 and ClGIs might be essential to initiate the flowering of C. lavandulifolium. This study provides the first extensive evaluation of circadian clock genes, and it presents a useful foundation for dissecting the functions of circadian clock genes in C. lavandulifolium.
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Affiliation(s)
- Jianxin Fu
- Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture and College of Landscape Architecture, Beijing Forestry University, Beijing 100083, China
| | - Liwen Yang
- Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture and College of Landscape Architecture, Beijing Forestry University, Beijing 100083, China
| | - Silan Dai
- Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture and College of Landscape Architecture, Beijing Forestry University, Beijing 100083, China.
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Matos DA, Cole BJ, Whitney IP, MacKinnon KJM, Kay SA, Hazen SP. Daily changes in temperature, not the circadian clock, regulate growth rate in Brachypodium distachyon. PLoS One 2014; 9:e100072. [PMID: 24927130 PMCID: PMC4057399 DOI: 10.1371/journal.pone.0100072] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 05/22/2014] [Indexed: 11/19/2022] Open
Abstract
Plant growth is commonly regulated by external cues such as light, temperature, water availability, and internal cues generated by the circadian clock. Changes in the rate of growth within the course of a day have been observed in the leaves, stems, and roots of numerous species. However, the relative impact of the circadian clock on the growth of grasses has not been thoroughly characterized. We examined the influence of diurnal temperature and light changes, and that of the circadian clock on leaf length growth patterns in Brachypodium distachyon using high-resolution time-lapse imaging. Pronounced changes in growth rate were observed under combined photocyles and thermocycles or with thermocycles alone. A considerably more rapid growth rate was observed at 28°C than 12°C, irrespective of the presence or absence of light. In spite of clear circadian clock regulated gene expression, plants exhibited no change in growth rate under conditions of constant light and temperature, and little or no effect under photocycles alone. Therefore, temperature appears to be the primary cue influencing observed oscillations in growth rate and not the circadian clock or photoreceptor activity. Furthermore, the size of the leaf meristem and final cell length did not change in response to changes in temperature. Therefore, the nearly five-fold difference in growth rate observed across thermocycles can be attributed to proportionate changes in the rate of cell division and expansion. A better understanding of the growth cues in B. distachyon will further our ability to model metabolism and biomass accumulation in grasses.
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Affiliation(s)
- Dominick A. Matos
- Biology Department, University of Massachusetts, Amherst, Massachusetts, United States of America
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Benjamin J. Cole
- Molecular and Computational Biology Section, University of Southern California, Los Angeles, California, United States of America
| | - Ian P. Whitney
- Biology Department, University of Massachusetts, Amherst, Massachusetts, United States of America
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Kirk J.-M. MacKinnon
- Biology Department, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Steve A. Kay
- Molecular and Computational Biology Section, University of Southern California, Los Angeles, California, United States of America
| | - Samuel P. Hazen
- Biology Department, University of Massachusetts, Amherst, Massachusetts, United States of America
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Müller LM, von Korff M, Davis SJ. Connections between circadian clocks and carbon metabolism reveal species-specific effects on growth control. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2915-23. [PMID: 24706717 DOI: 10.1093/jxb/eru117] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The plant circadian system exists in a framework of rhythmic metabolism. Much has been learned about the transcriptional machinery that generates the clock rhythm. Interestingly, these components are largely conserved between monocots and dicots, but key differences in physiological and developmental output processes have been found. How the clock coordinates carbon metabolism to drive plant growth performance is described with a focus on starch breakdown in Arabidopsis. It is proposed that clock effects on plant growth and fitness are more complex than just matching internal with external rhythms. Interesting recent findings support that the products of photosynthesis, probably sucrose, in turn feeds back to the clock to set its rhythm. In this way, the clock both controls and is controlled by carbon fluxes. This has an interesting connection to stress signalling and water-use efficiency, and it is now known that the clock and abscisic acid pathways are reciprocally coordinated. These processes converge to drive growth in a species-specific context such that predictions from the Arabidopsis model to other species can be restricted. This has been seen from phenotypic growth studies that revealed that dicot shoot growth is rhythmic whereas monocot shoot growth is continuous. Taken together, emerging evidence suggests reciprocal interactions between metabolism, the circadian clock, and stress signalling to control growth and fitness in Arabidopsis, but transferability to other species is not always possible due to species-specific effects.
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Affiliation(s)
- Lukas M Müller
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany
| | - Maria von Korff
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany Institute of Plant Genetics, Heinrich-Heine-University, Düsseldorf 40225, Germany Cluster of Excellence on Plant Sciences, Düsseldorf 40225, Germany
| | - Seth J Davis
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany Department of Biology, University of York, York, YO10 5DD, UK
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Ruts T, Matsubara S, Walter A. Synchronous high-resolution phenotyping of leaf and root growth in Nicotiana tabacum over 24-h periods with GROWMAP-plant. PLANT METHODS 2013; 9:2. [PMID: 23343327 PMCID: PMC3573902 DOI: 10.1186/1746-4811-9-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 01/17/2013] [Indexed: 05/03/2023]
Abstract
UNLABELLED BACKGROUND Root growth is highly responsive to temporal changes in the environment. On the contrary, diel (24 h) leaf expansion in dicot plants is governed by endogenous control and therefore its temporal pattern does not strictly follow diel changes in the environment. Nevertheless, root and shoot are connected with each other through resource partitioning and changing environments for one organ could affect growth of the other organ, and hence overall plant growth. RESULTS We developed a new technique, GROWMAP-plant, to monitor growth processes synchronously in leaf and root of the same plant with a high resolution over the diel period. This allowed us to quantify treatment effects on the growth rates of the treated and non-treated organ and the possible interaction between them. We subjected the root system of Nicotiana tabacum seedlings to three different conditions: constant darkness at 22°C (control), constant darkness at 10°C (root cooling), and 12 h/12 h light-dark cycles at 22°C (root illumination). In all treatments the shoot was kept under the same 12 h/12 h light-dark cycles at 22°C. Root growth rates were found to be constant when the root-zone environment was kept constant, although the root cooling treatment significantly reduced root growth. Root velocity was decreased after light-on and light-off events of the root illumination treatment, resulting in diel root growth rhythmicity. Despite these changes in root growth, leaf growth was not affected substantially by the root-zone treatments, persistently showing up to three times higher nocturnal growth than diurnal growth. CONCLUSION GROWMAP-plant allows detailed synchronous growth phenotyping of leaf and root in the same plant. Root growth was very responsive to the root cooling and root illumination, while these treatments altered neither relative growth rate nor diel growth pattern in the seedling leaf. Our results that were obtained simultaneously in growing leaves and roots of the same plants corroborate the high sensitivity of root growth to the environment and the contrasting robustness of diel growth patterns in dicot leaves. Further, they also underpin the importance to carefully control the experimental conditions for root growth analysis to avoid or/and minimize artificial complications.
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Affiliation(s)
- Tom Ruts
- Forschungszentrum Jülich GmbH, IBG-2: Plant Sciences, Jülich, Germany
| | - Shizue Matsubara
- Forschungszentrum Jülich GmbH, IBG-2: Plant Sciences, Jülich, Germany
| | - Achim Walter
- Forschungszentrum Jülich GmbH, IBG-2: Plant Sciences, Jülich, Germany
- ETH Zürich, Institute for Agricultural Sciences, Zürich, Switzerland
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10
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Barlow PW, Fisahn J. Lunisolar tidal force and the growth of plant roots, and some other of its effects on plant movements. ANNALS OF BOTANY 2012; 110:301-18. [PMID: 22437666 PMCID: PMC3394636 DOI: 10.1093/aob/mcs038] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 01/23/2012] [Indexed: 05/06/2023]
Abstract
BACKGROUND Correlative evidence has often suggested that the lunisolar tidal force, to which the Sun contributes 30 % and the Moon 60 % of the combined gravitational acceleration, regulates a number of features of plant growth upon Earth. The time scales of the effects studied have ranged from the lunar day, with a period of approx. 24.8 h, to longer, monthly or seasonal variations. SCOPE We review evidence for a lunar involvement with plant growth. In particular, we describe experimental observations which indicate a putative lunar-based relationship with the rate of elongation of roots of Arabidopsis thaliana maintained in constant light. The evidence suggests that there may be continuous modulation of root elongation growth by the lunisolar tidal force. In order to provide further supportive evidence for a more general hypothesis of a lunisolar regulation of growth, we highlight similarly suggestive evidence from the time courses of (a) bean leaf movements obtained from kymographic observations; (b) dilatation cycles of tree stems obtained from dendrograms; and (c) the diurnal changes of wood-water relationships in a living tree obtained by reflectometry. CONCLUSIONS At present, the evidence for a lunar or a lunisolar influence on root growth or, indeed, on any other plant system, is correlative, and therefore circumstantial. Although it is not possible to alter the lunisolar gravitational force experienced by living organisms on Earth, it is possible to predict how this putative lunisolar influence will vary at times in the near future. This may offer ways of testing predictions about possible Moon-plant relationships. As for a hypothesis about how the three-body system of Earth-Sun-Moon could interact with biological systems to produce a specific growth response, this remains a challenge for the future. Plant growth responses are mainly brought about by differential movement of water across protoplasmic membranes in conjunction with water movement in the super-symplasm. It may be in this realm of water movements, or even in the physical forms which water adopts within cells, that the lunisolar tidal force has an impact upon living growth systems.
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Affiliation(s)
- Peter W Barlow
- School of Biological Sciences, University of Bristol, Bristol, UK.
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11
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Abstract
Circadian regulated changes in growth rates have been observed in numerous plants as well as in unicellular and multicellular algae. The circadian clock regulates a multitude of factors that affect growth in plants, such as water and carbon availability and light and hormone signalling pathways. The combination of high-resolution growth rate analyses with mutant and biochemical analysis is helping us elucidate the time-dependent interactions between these factors and discover the molecular mechanisms involved. At the molecular level, growth in plants is modulated through a complex regulatory network, in which the circadian clock acts at multiple levels.
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Affiliation(s)
- E M Farré
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA.
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12
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Abstract
Plant organ phenotyping by noninvasive video imaging techniques provides a powerful tool to assess physiological traits, circadian and diurnal rhythms, and biomass production. In particular, growth of individual plant organs is known to exhibit a high plasticity and occurs as a result of the interaction between various endogenous and environmental processes. Thus, any investigation aiming to unravel mechanisms that determine plant or organ growth has to accurately control and document the environmental growth conditions. Here we describe challenges in establishing a recently developed plant root monitoring platform (PlaRoM) specially suited for noninvasive high-throughput plant growth analysis with highest emphasis on the detailed documentation of capture time, as well as light and temperature conditions. Furthermore, we discuss the experimental procedure for measuring root elongation kinetics and key points that must be considered in such measurements. PlaRoM consists of a robotized imaging platform enclosed in a custom designed phytochamber and a root extension profiling software application. This platform has been developed for multi-parallel recordings of root growth phenotypes of up to 50 individual seedlings over several days, with high spatial and temporal resolution. Two Petri dishes are mounted on a vertical sample stage in a custom designed phytochamber that provides exact temperature control. A computer-controlled positioning unit moves these Petri dishes in small increments and enables continuous screening of the surface under a binocular microscope. Detection of the root tip is achieved by applying thresholds on image pixel data and verifying the neighbourhood for each dark pixel. The growth parameters are visualized as position over time or growth rate over time graphs and averaged over consecutive days, light-dark periods and 24 h day periods. This setup enables the investigation of root extension profiles of different genotypes in various growth conditions (e.g., light protocol, temperature, growth media) and is especially suited for the detection of diurnal or circadian growth rhythms.
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