DOCSLIB.ORG

Beyond the View of Plants As Mere Machines: on Plant Sensation, Perception, and Awareness

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Beyond the View of Plants As Mere Machines: on Plant Sensation, Perception, and Awareness Beyond the View of Plants as Mere Machines: on Plant Sensation, Perception, and Awareness I‟ve always found plant behavior intriguing. Over the last six years of casual reading on it, starting with a college research report on the ill-named “Plant Neurobiology”, I learned more than I had imagined possible about the agency of plants (even after debunking misleading works such as The Secret Life of Plants). I learned that while plants do not possess a central nervous system, they nevertheless possess remarkable abilities of sensation, perception, and awareness. While these facets of life of course differ between plants and animals, plants nevertheless possess capacities for vision, olfaction, tactition, thermoception, and for detecting location, direction, and motion. Plants possess some forms of procedural memory, short-term memory, and long-term memory. They signal, communicate, and network with other organisms and species. They even wield a vascular system of awareness which some contrast to a central nervous system. All of these points serve to debunk the notion of plants as pure automata, as mere machines. But what, precisely, does that mean? Can a Plant “See”? Vision Without Eyes Plants can sense the ultraviolet spectrum, distinguish time of day based on sun, distinguish large and small light sources, distinguish parts of the light spectrum via phytochrome receptors, discern incoming light direction and duration as well as shadowing over themselves. Again, the decentralized rather than centralized nervous system: “If in the middle of the night you shine a beam of light on different parts of the plant, you discover that it‟s sufficient to illuminate any single leaf in order to regulate flowering in the entire plant.” [What a Plant Knows, p.20] Humans have rhodopsin detecting for light and shadow, and three photopsins for red, blue, and green, as well as cryptochrome for our internal clock. Plants have photoreceptors for blue and red lights as well, and, as photosynthesis-based organisms, depend on photoreceptor cues in ways more complex than humans; as an example, arabidopsis thaliana wields 11 different photoreceptors. Plants detect electromagnetic waves both longer and shorter than humans can. While we convert these signals to pictures, they convert it to growth cues. They detect, as well as respond adaptively. Indeed, plants also have their own comparable circadian rhythms. Can a Plant “Smell”? Olfaction Without Noses Plants also have the ability to perceive odor or scent through stimuli. Ethylene signaling for ripening demonstrates that plants have at least this volatile chemical receptor. As another example, the parasitic plant cuscuta pentagona locates its tomato host via multiple volatile chemical odors, avoiding noxious repellents. Many plants both anticipate and warn others toward phenolic and tannic chemical defense responses against predation via airborne pheromones, and some can responsively produce nectar attracting their predators‟ predators. They detect methyl salicylate odor, which they store and convert to salicylic acid for healing. Plants have pheromone senses like humans do, with limbic responses when they “smell trouble” or “the smell of fear”, just via different organs than humans. Can a Plant “Feel”? Tactition and Thermoception Without Brain or Skin “Not only do they know when they‟re being touched, but plants can differentiate between hot and cold, and know when their branches are swaying in the wind. Plants feel direct contact: some plants, like vines, immediately start rapid growth upon contact with an object like a fence they can wrap themselves around, and the Venus flytrap purposely snaps its jaws shut when an insect lands on its leaves. And plants seemingly don‟t like to be touched too much, as simply touching or shaking a plant can lead to growth arrest.” [What a Plant Knows, p.50] Regarding pressure perception, “…plants perceive tactile sensation, and some of them actually „feel‟ better than we do. Plants like the burr cucumber (Sicyos angulatus) are up to ten times more sensitive than we are when it comes to touch.” [What a Plant Knows, p.50] In plants, contact similarly initiates electric action potential across the organism, triggering mechanoreceptors. Bio-electrochemical currents via sodium, potassium, and calcium channels (similar to mammals) trigger hydraulic pumping, rather than bloodflow, modifying cell membranes and walls rather than muscles. However, “[w]hereas animals produce the action potential by an exchange of sodium and potassium ions, plant potentials are produced with calcium transport that is enhanced by chloride and reduced by potassium.” The process focuses on the pulvinus motor cells, rather than the brain neurons. Plants have touch-activated TCH genes, including one which encodes in plants the same calmodulin proteins involved in such animal processes as memory, inflammation, muscle function, and nerve growth. Electric communication from wounded to non- wounded leaves in a plant promotes adaptive responses, as does olfactory eavesdropping or perhaps signalling between plants. Current scientific research hypothesizes cellular level similarities between animals and plants, but organismal level difference, namely: complex mobile organisms (e.g. some animals) can feel pain, with an evolutionary basis, whereas sessile, rooted organisms (e.g. plants) employ metabolic responses but cannot feel pain. Plants lack the nociceptors indicative of pain- perception. Curiously, however, the same anesthetics that render animals unconscious can induce an unresponsive state in plants, and plants‟ ethylene can anesthetize animals. Additionally, some scientists claim plants signal using serotonin and dopamine, which function as neurotransmitters in animals. These both indicatesomething, though no one knows exactly what. Plants do however certainly detect temperature, and adapt to it. They can produce proteins to protect from the damage of ice formation or falling rates of enzyme catalysis at low temperatures, or enzyme denaturation and increased photorespiration at high temperatures. They can produce antifreeze proteins and dehydrins, or heat shock proteins, or antioxidant systems in case of the build-up of oxygen during metabolic imbalances at temperature extremes. They can change the composition of their membranes; increased unsaturated fatty acids for cold conditions, saturated fatty acids for hot conditions. Can a Plant “Navigate”? On Location, Direction, and Motion “…when a plant has been turned upside down, it will reorient itself in a slow-motion maneuver…so that its roots grow down and its shoots grow up”, “they‟re constantly aware of where their branches are; they know if they‟re growing perpendicular to the ground or at an angle off to one side, and tendrils always have a pretty good idea of where the nearest support is to grab onto.” [What a Plant Knows, p.91-92] Plants sense gravity via statoliths in root caps, rather than otoliths in ears, with their auxin providing the movement hormone. Each individual plant has a movement pattern, in particular a slow-motion, recurring, spiral sway performed throughout the day, inherently and in response to statolith settling and gravity. On Plant Memory “…plants clearly have the ability to retain past events and to recall this information at a later period for integration into their developmental framework: Tobacco plants know the color of the last light they saw. Willow trees know if their neighbors have been attacked by caterpillars. These examples, and many more, illustrate a delayed response to a previous occurrence, which is a key component to memory.” [What a Plant Knows, p.114] Memory requires the capacity to encode, retain, and retrieve information. Scientists have not found evidence for semantic or episodic memory in plants, but rather, procedural memory, as seen in the example that a “…tendril that had been touched in the dark had stored this information and recalled it once he placed it in the light.” [What a Plant Knows, p.115] Venus fly- trap behavior, as one example, demonstrates short-term memory via electric action potential and temporary ionic calcium concentrations. Plants also demonstrate long-term memory, for example through immune memory, or through morphogenetic trauma. “Morphogenetic memory is a type of memory that later influences the shape or form of the plant. In other words, a plant can experience a stimulus at some point, like a rip in its leaf or a fracture of a branch and be unaffected by it at first, but when environmental combinations change, the plant may remember the past experience and respond by changing its growth.” [What a Plant Knows, p.120] Regarding cellular memory, plants respond to weather cues across time (as seen with wheat vernalization). They, like animals, can have epigenetic adaptation (primarily toward environmental and physical stresses) which “…facilitates memory not only from season to season within a single organism but from generation to generation.” [What a Plant Knows, p.129] In fact, “…not only do the stressed plants make new combinations of DNA but their offspring also make the new combinations, even though they themselves had never been directly exposed to any stress. The stress in the parents caused a stable heritable change that was passed on to all their offspinrg: the plants behaved as if they‟d been stressed. They remembered that their parents had been through this stress and reacted similarly.” [What a Plant Knows, p.129] Animals have glutamate receptors responsible
Load more

Recommended publications
  • On Physical Heat Regulation and the Sense of Temperature In
    ON PHYSICAL HEAT REGULATION AND THE SENSE OF TEMPERA TURE IN MAN BY T. H. BENZINGER NAVAL MEDICAL RESEARCH INSTITUTE, BETHESDA, MARYLAND Communicated by Sterling Hendricks, February 26, 1959 Human physiology has given much of its attention to those systems which control in a multicellular organism the essential internal conditions: to respiration as it provides optimal concentrations of carbon dioxide, hydrogen ions and oxygen, to circulation as it maintains adequate blood flowrates and pressures, and to produc- tion and loss of energy as they are balanced through a regulatory mechanism for the maintenance of optimal body temperature. For the purpose of analysis, three main components may be distinguished with any regulatory system in physiology: 1. Specific sensory-receptor organs register the physical or chemical quantity that is to be regulated. They produce nerve impulses commensurate with the magnitude of this stimulus. 2. One or more effector organs act in response to the stimulus. This results in a return of the physical or chemical quantity registered toward the optimal level whereby the stimulus is reduced or abolished at the site of registration and else- where. 3. A coordinating center in the central nervous system receives the afferent nerve impulses. It produces efferent impulses which initiate or maintain the regulatory action of the effector organs. A physiological control mechanism cannot be considered clarified until its effector organs, center of coordination, and receptor sensory structures have been identified, and until the quantitative relations between causes and effects, that is, between physical or chemical stimuli and physiological responses, have been demonstrated. In this paper an attempt is described to clarify experimentally one of these mecha- nisms: the so-called "physical heat regulation"* of man.
    [Show full text]
  • The Plant Immune System: Induction, Memory and De-Priming of Defense
    The plant immune system : induction, memory and de-priming of defense responses by endogenous, exogenous and synthetic elicitors Kay Gully To cite this version: Kay Gully. The plant immune system : induction, memory and de-priming of defense responses by endogenous, exogenous and synthetic elicitors. Agricultural sciences. Université d’Angers, 2019. English. NNT : 2019ANGE0001. tel-02419987 HAL Id: tel-02419987 https://tel.archives-ouvertes.fr/tel-02419987 Submitted on 19 Dec 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Table of contents 1. Abbreviations ................................................................................................................... iv 2. Summary ......................................................................................................................... viii 2.1. Résumé en français ......................................................................................................... x 3. General Introduction ........................................................................................................
    [Show full text]
  • Plant Responses to Abiotic Stresses and Rhizobacterial Biostimulants: Metabolomics and Epigenetics Perspectives
    H OH metabolites OH Review Plant Responses to Abiotic Stresses and Rhizobacterial Biostimulants: Metabolomics and Epigenetics Perspectives Motseoa M. Lephatsi 1 , Vanessa Meyer 2 , Lizelle A. Piater 1 , Ian A. Dubery 1 and Fidele Tugizimana 1,3,* 1 Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa; [email protected] (M.M.L.); [email protected] (L.A.P.); [email protected] (I.A.D.) 2 School of Molecular and Cell Biology, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg 2050, South Africa; [email protected] 3 International Research and Development Division, Omnia Group, Ltd., Johannesburg 2021, South Africa * Correspondence: [email protected]; Tel.: +27-011-559-7784 Abstract: In response to abiotic stresses, plants mount comprehensive stress-specific responses which mediate signal transduction cascades, transcription of relevant responsive genes and the accumulation of numerous different stress-specific transcripts and metabolites, as well as coordinated stress-specific biochemical and physiological readjustments. These natural mechanisms employed by plants are however not always sufficient to ensure plant survival under abiotic stress conditions. Biostimulants such as plant growth-promoting rhizobacteria (PGPR) formulation are emerging as novel strategies for improving crop quality, yield and resilience against adverse environmental conditions. However, to successfully formulate these microbial-based biostimulants and design efficient application programs, the understanding of molecular and physiological mechanisms that govern biostimulant-plant interactions is imperatively required. Systems biology approaches, such as Citation: Lephatsi, M.M.; Meyer, V.; metabolomics, can unravel insights on the complex network of plant-PGPR interactions allowing for Piater, L.A.; Dubery, I.A.; Tugizimana, the identification of molecular targets responsible for improved growth and crop quality.
    [Show full text]
  • Thermoception
    THE FOURTH VIRTUAL DIMENSION Stimulating the Human Senses to Create Virtual Atmospheric Qualities LIAM JORDAN SHEEHAN1, ANDRE BROWN2, MARC AUREL SCHNABEL3 and TANE MOLETA4 1,2,3,4Victoria University of Wellington [email protected] 2,3,4{Andre.Brown|MarcAurel.Schnabel| Tane.Moleta}@vuw.ac.nz Abstract. In a move away from the ubiquitous ocular-centric Virtual Environment, our paper introduces a novel approach to creating other atmospheric qualities within VR scenarios that can address the known shortcoming of the feeling of disembodiment. In particular, we focus on stimulating the human body’s sensory ability to detect temperature changes: thermoception. Currently, users’ perceptions of a 3D virtual environment are often limited by the general focus, in VR development for design, on the two senses of vision and spatialised audio. The processes that we have undertaken include developing individual sensory engagement techniques, refinement of sensory stimuli and the generation of virtual atmospheric qualities. We respond to Pallasmaa’s theoretical stance on the evolution of the human senses, and the western bias of vision in virtual engine development. Consequently, the paper investigates the role our senses, outside of the core ’five senses’, have in creating a ’fourth virtual dimension’. The thermoception dimension is explored in our research. A user can begin to understand and engage with space and the directionality within a virtual scenario, as a bodily response to the stimulation of the body’s thermoception sense. Keywords. Virtual Reality; thermoception; sensory experience; immersion; atmosphere. 1. Introduction Experience, more precisely Human Experience, is set against the backdrop of the perception of space.
    [Show full text]
  • Segregation of an MSH1 Rnai Transgene Produces Heritable Non-Genetic Memory in Association with Methylome Reprogramming
    ARTICLE https://doi.org/10.1038/s41467-020-16036-8 OPEN Segregation of an MSH1 RNAi transgene produces heritable non-genetic memory in association with methylome reprogramming Xiaodong Yang 1,4, Robersy Sanchez 1,4, Hardik Kundariya 1,2,4, Tom Maher1, Isaac Dopp1, ✉ Rosemary Schwegel1, Kamaldeep Virdi 2, Michael J. Axtell3 & Sally A. Mackenzie 1 fi MSH1 1234567890():,; MSH1 is a plant-speci c protein. RNAi suppression of results in phenotype variability for developmental and stress response pathways. Segregation of the RNAi transgene pro- duces non-genetic msh1 ‘memory’ with multi-generational inheritance. First-generation memory versus non-memory comparison, and six-generation inheritance studies, identifies gene-associated, heritable methylation repatterning. Genome-wide methylome analysis integrated with RNAseq and network-based enrichment studies identifies altered circadian clock networks, and phytohormone and stress response pathways that intersect with circa- dian control. A total of 373 differentially methylated loci comprising these networks are sufficient to discriminate memory from nonmemory full sibs. Methylation inhibitor 5- azacytidine diminishes the differences between memory and wild type for growth, gene expression and methylation patterning. The msh1 reprogramming is dependent on functional HISTONE DEACETYLASE 6 and methyltransferase MET1, and transition to memory requires the RNA-directed DNA methylation pathway. This system of phenotypic plasticity may serve as a potent model for defining accelerated plant adaptation during environmental change. 1 Departments of Biology and Plant Science, The Pennsylvania State University, University Park, PA, USA. 2 Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE, USA. 3 Department of Biology, The Pennsylvania State University, University Park, PA, USA.
    [Show full text]
  • “Lacking Warmth” Alexithymia Trait Is Related to Warm-Specific Thermal Somatosensory Processing
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by UCL Discovery Biological Psychology 128 (2017) 132–140 Contents lists available at ScienceDirect Biological Psychology journal homepage: www.elsevier.com/locate/biopsycho “Lacking warmth”: Alexithymia trait is related to warm-specific thermal MARK somatosensory processing ⁎ Khatereh Borhania,b,c,d, Elisabetta Làdavasb,c, Aikaterini Fotopouloue, Patrick Haggarda, a Institute of Cognitive Neuroscience, University College London, London, UK b Department of Psychology, University of Bologna, Viale Berti Pichat 5, 40127 Bologna, Italy c CSRNC, Centre for Studies and Research in Cognitive Neuroscience, University of Bologna, Viale Europa 980, 47521 Cesena, Italy d Institute of Cognitive and Brain Sciences, Shahid Beheshti University, Tehran, Iran e Division of Psychology and Language Sciences, University College London, London, UK ARTICLE INFO ABSTRACT Keywords: Alexithymia is a personality trait involving deficits in emotional processing. The personality construct has been Alexithymia extensively validated, but the underlying neural and physiological systems remain controversial. One theory Somatosensory processig suggests that low-level somatosensory mechanisms act as somatic markers of emotion, underpinning cognitive Emotion processing and affective impairments in alexithymia. In two separate samples (total N = 100), we used an established Quantitative sensory testing (QST) Quantitative Sensory Testing (QST) battery to probe multiple neurophysiological submodalities of somato- Thermal perception sensation, and investigated their associations with the widely-used Toronto Alexithymia Scale (TAS-20). Experiment one found reduced sensitivity to warmth in people with higher alexithymia scores, compared to individuals with lower scores, without deficits in other somatosensory submodalities. Experiment two replicated this result in a new group of participants using a full-sample correlation between threshold for warm detection and TAS-20 scores.
    [Show full text]
  • Sensitisation of Nociceptors – What Are Ion Channels Doing?
    82 The Open Pain Journal, 2010, 3, 82-96 Open Access Sensitisation of Nociceptors – What are Ion Channels Doing? Michael J.M. Fischer*, Stephanie W.Y. Mak and Peter A. McNaughton Department of Pharmacology, University of Cambridge, UK Abstract: Nociceptors are peripheral sensory neurones which respond to painful (noxious) stimuli. The terminals of nociceptors, which have a high threshold to stimulation in their native state, undergo a process known as sensitisation, or lowering of threshold, following injury or inflammation. Amongst sensory receptors, sensitisation is a property unique to nociceptors. A shift in the stimulus-response function of nociceptors renders them more sensitive, resulting in both a reduction in the activation threshold, such that previously non-noxious stimuli are perceived as noxious (allodynia) and an increased response to suprathreshold stimuli (hyperalgesia). Sensitisation protects us from harm and is essential for survival, but it can be disabling in conditions of chronic inflammation. This review focuses on three stages in sensitisation: 1) Inflammatory mediators, which are released from damaged resident cells and from others that invade in response to inflammation, and include bradykinin, prostaglandins, serotonin, low pH, ATP, neurotrophins, nitric oxide and cytokines; 2) Intracellular signalling molecules which are important in transmitting the actions of inflammatory mediators and include protein kinase A and C, Src kinase, mitogen-activated protein kinases and the membrane lipid PIP2; and 3) Ion channel targets of intracellular signalling which ultimately cause sensitisation and include the temperature- sensitive transient receptor potential channels, acid-sensitive ion channels, purinoceptor-gated channels, and the voltage- sensitive sodium, potassium, calcium and HCN channels.
    [Show full text]
  • THE INTELLIGENT PLANT Scientists Debate a New Way of Understanding Flora
    Michael Pollan: How Smart Are Plants? : The New Yorker Page 1 of 21 A REPORTER AT LARGE THE INTELLIGENT PLANT Scientists debate a new way of understanding flora. by Michael Pollan DECEMBER 23, 2013 •Print •More Share Close ◦ ◦ Reddit ◦ Linked In ◦ Email ◦ ◦ StumbleUpon n 1973, a book claiming that plants were sentient Ibeings that feel emotions, prefer classical music to rock and roll, and can respond to the unspoken thoughts of humans hundreds of miles away landed on the New York Times best-seller list for nonfiction. “The Secret Life of Plants,” by Peter Tompkins and Christopher Bird, presented a beguiling mashup of legitimate plant science, quack experiments, and mystical nature worship that captured the public imagination at a time when New Age thinking was seeping into the mainstream. The most memorable passages described the experiments of a former C.I.A. polygraph expert named Cleve Backster, who, in Plants have electrical and chemical 1966, on a whim, hooked up a galvanometer to the signalling systems, may possess memory, and exhibit brainy behavior in the absence of leaf of a dracaena, a houseplant that he kept in his brains. Construction by Stephen Doyle. office. To his astonishment, Backster found that simply by imagining the dracaena being set on fire he could make it rouse the needle of the http://www.newyorker.com/reporting/2013/12/23/131223fa_fact_pollan?printable=true&... 09/01/2014 Michael Pollan: How Smart Are Plants? : The New Yorker Page 2 of 21 polygraph machine, registering a surge of electrical activity suggesting that the plant felt stress. “Could the plant have been reading his mind?” the authors ask.
    [Show full text]
  • Are Plants Cognitive?
    Studies in History and Philosophy of Science xxx (xxxx) xxx–xxx Contents lists available at ScienceDirect Studies in History and Philosophy of Science journal homepage: www.elsevier.com/locate/shpsa Are plants cognitive? A reply to Adams ∗ Miguel Segundo-Ortina, Paco Calvob, a Faculty of Law, Humanities and the Arts, University of Wollongong, Australia b Minimal Intelligence Lab (MINT Lab), Universidad de Murcia, Spain HIGHLIGHTS • Offers an empirically informed philosophical discussion of plant intelligence. • Discusses crucial aspects of the nervous-like vascular system of plants. • Explores important analogies between plant and animal behavior. ARTICLE INFO ABSTRACT Keywords: According to F. Adams [this journal, vol. 68, 2018] cognition cannot be realized in plants or bacteria. In his Adams view, plants and bacteria respond to the here-and-now in a hardwired, inflexible manner, and are therefore Plant cognition incapable of cognitive activity. This article takes issue with the pursuit of plant cognition from the perspective of Adaptive behavior an empirically informed philosophy of plant neurobiology. As we argue, empirical evidence shows, contra Anticipation Adams, that plant behavior is in many ways analogous to animal behavior. This renders plants suitable to be Learning described as cognitive agents in a non-metaphorical way. Sections two to four review the arguments offered by Enactivism Adams in light of scientific evidence on plant adaptive behavior, decision-making, anticipation, as well learning and memory. Section five introduces the ‘phyto-nervous’ system of plants. To conclude, section six resituates the quest for plant cognition into a broader approach in cognitive science, as represented by enactive and ecological schools of thought.
    [Show full text]
  • B-Afferents: a Fundamental Division of the Nervous System Mediating Hoxneostasis?
    Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 1990 Dichotomic classification of sensory neurons: Elegant but problematic Neuhuber, W L DOI: https://doi.org/10.1017/s0140525x00078882 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-154322 Journal Article Published Version Originally published at: Neuhuber, W L (1990). Dichotomic classification of sensory neurons: Elegant but problematic. Behav- ioral and Brain Sciences, 13(02):313-314. DOI: https://doi.org/10.1017/s0140525x00078882 BEHAVIORAL AND BRAIN SCIENCES (1990) 13, 289-331 Printed in the United States of America B-Afferents: A fundamental division of the nervous system mediating hoxneostasis? James C. Prechtl* Terry L* Powley Laboratory of Regulatory Psychobiology, Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907 Electronic mail: [email protected]@brazil.psych.edu *Reprint requests should be addressed to: James C. Prechtl, Department of Neuroscience, A-001, University of California, San Diego, La Jolla, CA 92093 Abstract? The peripheral nervous system (PNS) has classically been separated into a somatic division composed of both afferent and efferent pathways and an autonomic division containing only efferents. J. N. Langley, who codified this asymmetrical plan at the beginning of the twentieth century, considered different afferents, including visceral ones, as candidates for inclusion in his concept of the "autonomic nervous system" (ANS), but he finally excluded all candidates for lack of any distinguishing histological markers. Langley's classification has been enormously influential in shaping modern ideas about both the structure and the function of the PNS.
    [Show full text]
  • Dynamics and Function of DNA Methylation in Plants
    REVIEWS Dynamics and function of DNA methylation in plants Huiming Zhang1,2*, Zhaobo Lang1,2 and Jian- Kang Zhu 1,2,3* Abstract | DNA methylation is a conserved epigenetic modification that is important for gene regulation and genome stability. Aberrant patterns of DNA methylation can lead to plant developmental abnormalities. A specific DNA methylation state is an outcome of dynamic regulation by de novo methylation, maintenance of methylation and active demethylation, which are catalysed by various enzymes that are targeted by distinct regulatory pathways. In this Review, we discuss DNA methylation in plants, including methylating and demethylating enzymes and regulatory factors, and the coordination of methylation and demethylation activities by a so- called methylstat mechanism; the functions of DNA methylation in regulating transposon silencing, gene expression and chromosome interactions; the roles of DNA methylation in plant development; and the involvement of DNA methylation in plant responses to biotic and abiotic stress conditions. DNA methylation at the 5ʹ position of cytosine contrib- and regulatory factors are generally not lethal. However, utes to the epigenetic regulation of nuclear gene expres- DNA methylation appears to be more crucial for devel- sion and to genome stability1,2. Epigenetic changes, opment and environmental- stress responses in plants including DNA methylation, histone modifications and that have more complex genomes. Recent findings histone variants and some non- coding RNA (ncRNA) have uncovered important
    [Show full text]
  • Epigenetic Memory and Growth Responses of the Clonal Plant Glechoma Longituba to Parental Recurrent UV-B Stress
    CSIRO PUBLISHING Functional Plant Biology, 2021, 48, 827–838 https://doi.org/10.1071/FP20303 Epigenetic memory and growth responses of the clonal plant Glechoma longituba to parental recurrent UV-B stress Xiaoyin Zhang A, Cunxia Li A, Dan Tie A, Jiaxin Quan A, Ming Yue A and Xiao Liu A,B AKey Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi’an 710069, China. BCorresponding author. Email: [email protected] Abstract. The responses of plants to recurrent stress may differ from their responses to a single stress event. In this study, we investigated whether clonal plants can remember past environments. Parental ramets of Glechoma longituba (Nakai) Kuprian were exposed to UV-B stress treatments either once or repeatedly (20 and 40 repetitions). Differences in DNA methylation levels and growth parameters among parents, offspring ramets and genets were analysed. Our results showed that UV-B stress reduced the DNA methylation level of parental ramets, and the reduction was enhanced by increasing the number of UV-B treatments. The epigenetic variation exhibited by recurrently stressed parents was maintained for a long time, but that of singly stressed parents was only short-term. Moreover, clonal plants responded to different UV-B stress treatments with different growth strategies. The one-time stress was a eustress that increased genet biomass by increasing offspring leaf allocation and defensive allocation in comparison to the older offspring. In contrast, recurring stress was a distress that reduced genet biomass, increased the biomass of storage stolons, and allocated more defensive substances to the younger ramets.
    [Show full text]