DOCSLIB.ORG

Translocation of Neonicotinoid Insecticides from Coated Seeds to Seedling Guttation Drops: a Novel Way of Intoxication for Bees

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Translocation of Neonicotinoid Insecticides from Coated Seeds to Seedling Guttation Drops: a Novel Way of Intoxication for Bees ECOTOXICOLOGY Translocation of Neonicotinoid Insecticides From Coated Seeds to Seedling Guttation Drops: A Novel Way of Intoxication for Bees V. GIROLAMI,1,2 L. MAZZON,1 A. SQUARTINI,3 N. MORI,1 M. MARZARO,1 A. DI BERNARDO,1 4 5 5 M. GREATTI, C. GIORIO, AND A. TAPPARO J. Econ. Entomol. 102(5): 1808Ð1815 (2009) ABSTRACT The death of honey bees, Apis mellifera L., and the consequent colony collapse disorder causes major losses in agriculture and plant pollination worldwide. The phenomenon showed in- creasing rates in the past years, although its causes are still awaiting a clear answer. Although neonicotinoid systemic insecticides used for seed coating of agricultural crops were suspected as possible reason, studies so far have not shown the existence of unquestionable sources capable of delivering directly intoxicating doses in the Þelds. Guttation is a natural plant phenomenon causing the excretion of xylem ßuid at leaf margins. Here, we show that leaf guttation drops of all the corn plants germinated from neonicotinoid-coated seeds contained amounts of insecticide constantly higher than 10 mg/l, with maxima up to 100 mg/l for thiamethoxam and clothianidin, and up to 200 mg/l for imidacloprid. The concentration of neonicotinoids in guttation drops can be near those of active ingredients commonly applied in Þeld sprays for pest control, or even higher. When bees consume guttation drops, collected from plants grown from neonicotinoid-coated seeds, they en- counter death within few minutes. KEY WORDS guttation, neonicotinoid, honey bee, seed coating Phytophagous insects occurring in soil at sowing time 2008). The reduced load of insecticide per Þeld unit, tend to concentrate around on corn, Zea mays L., allowed by conÞning it on the seed, represents main seedlings causing extensive damage. Granular insec- advantages in environmental terms compared with ticides applied to the soil have been the method of former products requiring whole-soil or furrow appli- choice for their control for a long time. More recently, cations. Elbert et al. (2008) pointed out impressive the strategy has been surpassed by the seed coating Þgures revealing the turnover toward insecticidal seed technique using neonicotinoids, which are active treatment. Starting from: a niche-level market of €155 against a broad range of pest species, including wire- million in 1990, mostly represented by carbamates, by worms (Agriotes spp.) and the rootworm Diabrotica 2005 seed coating developed into a €535 million mar- virgifera virgifera LeConte (Altmann 2003). ket, with a 77% share for neonicotinoid insecticides. Among the main reasons of success of neonicotin- The loss of pollinating bees is a worldwide crisis. In oids is their systemic action. Upon application on the particular it became manifest as colony collapse dis- seed surface, the active compound is translocated and order (CCD), characterized by a sudden disappear- distributed throughout the whole plant, conferring a ance of worker bees that do not return to the hive. substantial and long-lasting control of insects and pro- Parasitic mites and viruses have come under suspicion, tecting young plants also from sucking leafhoppers although no clear conclusions could be drawn as con- and aphids (Magalhaes et al. 2009), which are poten- cerns these biotic causes. Pesticides have been shown tial vectors of plant virus (MaienÞsch et al. 2001). to be more directly involved and in recent years the Nowadays, neonicotinoids are widely used for seed attention has been focused on neonicotinoids (imi- treatment in cotton (Gossypium spp.), sugarbeet (Beta dacloprid, clothianidin, and thiamethoxam), a class of vulgaris L.), oilseed rape (Brassica napus L.) corn (Zea insecticides among the most widely used worldwide. mays L.), and other cereals and crops (Elbert et al. The effects of neonicotinoids, such as imidacloprid on honey bees (Suchail et al. 2000, Maus et al. 2003) could 1 Dipartimento di Agronomia Ambientale e Produzioni Vegetali, be consistent with the symptoms of CCD. However, Entomologia, Universita` di Padova, Viale dellÕUniversita` 16, 35020 the blame on neonicotinoids has not yet been con- Legnaro (Padova) Italy. 2 Corresponding author, e-mail: [email protected]. clusive as the amounts detected in nectar and pollen 3 Dipartimento di Biotecnologie Agrarie, Universita` di Padova, of plants grown from treated seeds were lower than 10 Viale dellÕUniversita` 16, 35020 Legnaro (Padova) Italy. ng/g (10 ppb), whereas higher doses, as Ͼ40 ␮g/liter 4 Dipartimento di Biologia e Protezione delle Piante, Entomologia, (40 ppb) are necessary for abnormal honey bee for- Universita` di Udine, Via delle Scienze 208, 33100 Udine, Italy. Ͼ 5 Dipartimento di Scienze Chimiche, Universita` di Padova, Via aging behavior, 0.5 mg/liter (0.5 ppm) for the Þrst Marzolo 1, 35131 Padova, Italy. missing bees, and Ͼ3 mg/liter (3 ppm) for 100% of the 0022-0493/09/1808Ð1815$04.00/0 ᭧ 2009 Entomological Society of America October 2009 GIROLAMI ET AL.: GUTTATION TOXICITY OF SEEDLING FROM COATED SEEDS 1809 bees failing to return to a source of sugar offered to Þpronil (Regent 500 FS, BASF SE, Ludwigshafen, Ger- them (Yang et al. 2008). many; 1 mg/seed). The last nonsystemic compound is In Italy, a highly recurring coincidence between a member of the phenyl pyrazole class of pesticides. corn sowing time and bee death has been noticed Each of the four insecticides mentioned was a regu- previously (Greatti et al. 2003, Greatti et al. 2006), larly registered product for corn seed coating in Italy leading to the hypothesis that solid coating debris and in 2008. Seeds used (hybrid PR34N84) were from dust uplifted from sowing machines could fall over Pioneer Hi-Bred Italy (Johnston, IA), and all also were nearby vegetation and contaminate wildßowers. coated with the fungicide Celest XL (Syngenta), Within the same frame of thought, we postulated based on Fludioxonil (2.4%) and Metalaxyl-M that a different and hitherto overlooked source of (0.93%). The untreated control was also from Pioneer directly lethal doses could be present in the Þelds, and Hi-Bred (for biological agriculture) and belonged to we took into consideration the hypothesis that intox- the hybrid PR33A46. icating concentrations could accumulate in guttation In Þeld crops, we had cases treated with each of the drops of young corn plants. above-mentioned compounds. For potted plants, we Guttation (from the Latin “gutta”ϭdrop) is the for- focused essentially on imidacloprid. mation of drops of xylem sap on the tips or along the Collection of Guttation Drops. During spring edges of leaves. It is a physiological phenomenon oc- (April) corn seedlings were grown in open Þeld, curring in many vascular plants, in particular grasses, spaced 20 cm within the row and 75 cm between rows. water entering roots creates a slight pressure that In subsequent periods (May), tests were replicated by forces it to rise and be exuded through the hydatodes sowing coated seeds in pots with a diameter of 15 cm at leaf margins. This is a regular occurrence in many and growing two to Þve plants per pot in the labora- plants and is not restricted to nighttime, although in tory. In total, six to eight pots for each compound were the dark stomatal closure can lead to higher internal used and equal numbers were sown with uncoated pressure that increases guttation drop volumes, seeds as control, or with seeds coated with fungicides. thereby enhancing the visibility of the phenomenon For each seedling, we gathered all guttation drops (Goatley and Lewis 1966, Koulman et al. 2007). Gut- at all plant levels, by using Pasteur micropipettes. tation is common but often unnoticed as easily con- Collection in the Þeld was carried out from 8:00 to 9:00 fused with dew characterized by small condensation a.m. from all plants within a row, until a volume of 5 drops from atmospheric humidity. Guttation drop can ml was available. In the laboratory, because guttation roll off, evaporate or may be sucked back into the leaf occurs throughout the days and night, it was possible (Chen and Chen 2007). to collect them three times a day, yielding a volume of Bees require intense drinking activity (Visscher et Ϸ1Ð2 ml/d. Samples were stored at ϩ2ЊC. Half of the al. 1996, Ku¨ hnholz and Seeley 1997) and have been volume was sent for chemical analyses and half for reported to collect guttation water (Shawki et al. toxicity bioassays, which were normally performed 2005). within 2Ð3 d. In the current study, we wanted to verify whether Collection of guttation drops was carried out from neonicotinoids used for seed coating could be trans- corn emergence up to the Þrst 3 wk for each of the located in guttation drops and reach concentrations treatments as subsequently the phenomenon ceased toxic to bees. In parallel, we tested the toxicity of serial in its intensity both in the Þeld and in the laboratory. concentrations of these insecticides by setting up a Insecticide Content in Guttation Drops. Pure test apt to evaluate, in reasonably short time, the chemicals for the preparation of solutions of thiame- appearance of intoxication symptoms in bees upon thoxam, clothianidin, imidacloprid, and Þpronil, to be consumption of neonicotinoid aqueous solutions. used for reference toxicity curves and as analytical determination standards, were from Fluka (Sigma- Aldrich Group, Milan, Italy; Pestanal, purity Ͼ99.7% Materials and Methods for thiamethoxam, clothianidin, imidacloprid, Ͼ97.6% Insect Origin. Trials were carried out in the exper- for Þpronil). Methanol (VWR, International, Milan, imental farm of the faculty of Agriculture (University Italy), and acetonitrile (Riedel de Hae¨n, Sigma-Al- of Padova) located in Legnaro, Italy. Bees (Apis mel- drich Group) were of high-performance liquid chro- lifera L.) used for the tests were collected from dif- matography (HPLC) grade. Pure water was produced ferent colonies residing within the farmÕs Þeld facili- by Milli-Q equipment (Millipore, Billerica, MA).
Load more

Recommended publications
  • Plant Water Relations: Absorption, Transport and Control Mechanisms
    5 Plant Water Relations: Absorption, Transport and Control Mechanisms Geraldo Chavarria1 and Henrique Pessoa dos Santos2 1The University of Passo Fundo 2Embrapa Grape & Wine Brazil 1. Introduction Although water is abundant on Earth - covering 71% of the total surface - its distribution is not uniform and can easily cause restrictions in availability to vegetal production. At global scale, these restrictions are easily observed in dry climates and can appear in other regions which do not currently experience drought, as provided by the future backdrop of climate change (IPCC, 2007). The influences of water restriction on losses in the production and distribution of vegetation on the terrestrial surface are significantly larger than all other losses combined which are caused by biotic and abiotic factors (Boyer, 1985). This striking effect of water on plants emerges from its physiological importance, being an essential factor for successful plant growth, involving photosynthesis and several other biochemical processes such as the synthesis of energetic composites and new tissue. Therefore, in order to characterise the growth and productive behaviour of plant species it is essential to have an understanding of plant water relations, as well as the consequences of an inadequate water supply. Broadly, the water state of a plant is controlled by relative rates of loss and absorption, moreover it depends on the ability to adjust and keep an adequate water status. This will be considered throughout this chapter. 2. Absorption and water flow through plants Independent of the species, plants require from the soil a water volume that overcomes its metabolic necessities. Through the transpiration process plants transmit to the atmosphere the majority of the water absorbed from soil (generally around 90%).
    [Show full text]
  • Anatomy of Leaf Apical Hydathodes in Four Monocotyledon Plants of Economic and Academic Relevance Alain Jauneau, Aude Cerutti, Marie-Christine Auriac, Laurent D
    Anatomy of leaf apical hydathodes in four monocotyledon plants of economic and academic relevance Alain Jauneau, Aude Cerutti, Marie-Christine Auriac, Laurent D. Noël To cite this version: Alain Jauneau, Aude Cerutti, Marie-Christine Auriac, Laurent D. Noël. Anatomy of leaf apical hydathodes in four monocotyledon plants of economic and academic relevance. PLoS ONE, Public Library of Science, 2020, 15 (9), pp.e0232566. 10.1371/journal.pone.0232566. hal-02972304 HAL Id: hal-02972304 https://hal.inrae.fr/hal-02972304 Submitted on 20 Oct 2020 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. Distributed under a Creative Commons Attribution| 4.0 International License PLOS ONE RESEARCH ARTICLE Anatomy of leaf apical hydathodes in four monocotyledon plants of economic and academic relevance 1☯ 2☯ 1,2 2 Alain Jauneau *, Aude Cerutti , Marie-Christine Auriac , Laurent D. NoeÈlID * 1 FeÂdeÂration de Recherche 3450, Universite de Toulouse, CNRS, Universite Paul Sabatier, Castanet- Tolosan, France, 2 LIPM, Universite de Toulouse, INRAE, CNRS, Universite Paul Sabatier, Castanet- Tolosan, France ☯ These authors contributed equally to this work. a1111111111 * [email protected] (AJ); [email protected] (LN) a1111111111 a1111111111 a1111111111 a1111111111 Abstract Hydathode is a plant organ responsible for guttation in vascular plants, i.e.
    [Show full text]
  • 3115 SAPS Operating Instructions
    OPERATING INSTRUCTIONS FIELD PLANT WATER STATUS CONSOLE March 2017 Fig. 1 - Model 3115 Portable Plant Water Console shown with 22 c/f Compressed Gas Cylinder, 3072V22 SOILMOISTURE EQUIPMENT CORP. P.O. Box 30025, Santa Barbara, CA 93105 U.S.A. Telephone 805-964-3525 - Fax No. 805-683-2189 Email: [email protected] - Website: http://www.soilmoisture.com Table of Contents Chapter - Page 1 Description ............................................................................................................................... 1 - 4 2 Technical Specification ............................................................................................................ 2 - 5 2.1 Weight .......................................................................................................................... 2 - 5 2.2 Dimensions ................................................................................................................... 2 - 5 2.3 Pressure Vessel ............................................................................................................. 2 - 5 2.4 Gauges .......................................................................................................................... 2 - 5 2.5 Valves ........................................................................................................................... 2 - 5 2.6 Connecting Hose .......................................................................................................... 2 - 5 2.7 Pressure Tank ..............................................................................................................
    [Show full text]
  • Differences Between Transpiration and Guttation
    BIOLOGY TRANSPIRATION Significance and Factors affecting Transpiration Factors Affecting the Rate of Transpiration •On a bright sunny day, stomata open fully, so transpiration is increased. •On a cloudy day, stomata open partially, so Intensity of sunlight transpiration is reduced. •At night, stomata close; hence, transpiration is greatly reduced or negligible. •Increase in temperature of the air increases the rate Temperature of transpiration. •Transpiration increases with rapid or active air Velocity of wind movement. Humidity •If the air is humid, the rate of transpiration is reduced. •Increase in the CO2 level in the atmosphere over Carbon dioxide normal 0.03% causes stomatal closure. Hence, it decreases the rate of transpiration. •With decrease in atmospheric pressure, the rate of Atmospheric pressure transpiration increases. www.topperlearning.com 2 BIOLOGY TRANSPIRATION Adaptation in Plants to Control Excessive Transpiration Plants which grow in dry climate have evolved a variety of adaptations to curtail transpiration. Morphological Leaves may be modified into spines as in cactus or into needles as in pines. Adaptations Spines Needles Leaves may be folded or rolled up. Rolled up Leaves Leaves may be shed. Example: deciduous trees. Deciduous Trees Anatomical The number of stomata is reduced, and they may be sunken in pits. Adaptations Sunken Stoma www.topperlearning.com 3 BIOLOGY TRANSPIRATION Structure of Sunken Stomata A thick waxy cuticle develops on the leaves. Example: Banyan tree, evergreen trees. Banyan Tree Shrubs and grass develop a waterproof covering of cork or bark. A multiple epidermis may develop in some leaves. www.topperlearning.com 4 BIOLOGY TRANSPIRATION Significance of Transpiration Cooling Effect Suction Force Distribution of Water and Mineral Salts Evaporation reduces the As water evaporates from leaves, Higher the rate of transpiration, temperature of leaf a suction force is created.
    [Show full text]
  • Anatomy of Epithemal Hydathodes in Four Monocotyledon Plants of Economic and Academic
    bioRxiv preprint doi: https://doi.org/10.1101/2020.04.20.050823; this version posted April 20, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 Anatomy of epithemal hydathodes in four monocotyledon plants of economic and academic 2 relevance 3 4 Running title: Anatomy of monocot hydathodes 5 6 Alain Jauneau 1*, Aude Cerutti 2, Marie-Christine Auriac 1,2 and Laurent D. Noël 2* 7 8 1 Fédération de Recherche 3450, Université de Toulouse, CNRS, Université Paul Sabatier, Castanet- 9 Tolosan, France 10 2 LIPM, Université de Toulouse, INRAE, CNRS, Université Paul Sabatier, Castanet-Tolosan, France 11 * Authors for correspondence: 12 Alain Jauneau; Institut Fédératif de Recherche 3450, Plateforme Imagerie, Pôle de Biotechnologie 13 Végétale, Castanet-Tolosan 31326, France; E-mail: [email protected] 14 Laurent D. Noël; Laboratoire des interactions plantes micro-organismes (LIPM), UMR2594/441 15 CNRS/INRA, chemin de Borde Rouge, CS52627, F-31326 Castanet-Tolosan Cedex, France; Tel: 16 +33 5 6128 5047; E-mail: [email protected]. 17 18 AJ and AC contributed equally to this study 19 20 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.04.20.050823; this version posted April 20, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.
    [Show full text]
  • Ch. 36 Transport in Vascular Plants
    Ch. 36 Transport in Vascular Plants Feb 4­1:32 PM 1 Essential Question: How does a tall tree get the water from its roots to the top of the tree? Feb 4­1:38 PM 2 Shoot architecture and Light Capture: Phyllotaxy ­ arrangement of leaves on a stem to maximize light capture, reduce self shading ­ determined by shoot apical meristem and specific to each species ­alternate = one leaf per node ­opposite = two leaves per node ­whorled = more than two leaves per node Norway spruce ­ 1 is youngest leaf Apr 14­7:00 AM 3 leaf area index = ratio of total upper leaf surface of a single plant divided by surface area of land, normal value ~ 7 if above 7 ­ leaves,branches undergo self pruning ­ programmed cell death Mar 28­2:46 PM 4 Leaf orientations: horizontal leaf orientation ­ for low­light, capture sunlight more effectively vertical leaf orientation ­ for high light, grasses, light rays coming in parallel to leaf so not too much light Apr 14­7:05 AM 5 Root architecture: mychorrhizae ­ mutualistic relationship between fungi and roots ­80% of land plants have this ­increases surface area for water and mineral absorption Mar 28­2:49 PM 6 Overview of transport in trees Feb 6­9:37 AM 7 Three types of transport in vascular plants: 1. transport of water and solutes by individual cells a. passive transport (osmosis) through aquaporins ­ transport proteins water potential ­ combined effects of solute concentration and physical pressure (esp. in plants due to cell wall) ­determines direction of movement of water ­free water moves high to low [ ] ­measured in megapascals (MPa) ­water potential = "0" in an open container (at sea level and rm.
    [Show full text]
  • Internal Organisation of Plants
    INTERNAL ORGANISATION OF PLANTS • In unicellular and colonial forms every cell behaves as an independent unit and performs all functions • Levels of organisation in plant Anatomy are Tissues - Tissue systems - Organs - Plant body. • Study of tissues and tissue systems of plant body is called Histology • A group of similar or dissimilar cells that have a common origin and function is called tissue. • Tissues are formed as a response to division of labour. Tissues are of two types namely. A) Meristematic tissue B) Permanent tissue. A) Meristamatic tissue: A group of undifferentiated cells having the power of cell division is called Meristematic tissue or Formative tissue. The term 'meristem' was coined by K. Nageli (1858) Characters of meristematic tissue i) Cells are smallin size and isodiametric, cubical or polyhedral in shape. ii) Cells are young and immature iii) Cells are arranged compactly without intercellular spaces. iv) Cell wall is thin and formed of cellulose. v) Dense cytoplasm and abundant with numerous smaller vacuoles vi) Proplastids are present. vii) Ergastic substances absent. viii) Prominent big Nucleus is present ix) Cells divide continously and show active metabolism. Types of Meristems: Basing on origin, meristems are classified into two types namely Primary meristems & Secondary meristems. Meristems which originate from embryonic tissues and continue to remain active in mature parts of the plant is called primary meristems. (mainly seen in apices of root which is continuation of radical) and main stem which is continuation of Plumule) Meristem derived from permanent cells by dedifferentiation is called secondary meristem. Eg: Interfascicular cambium, and cork cambium etc. Secondary meristems are lateral in position parallel to the periphery and help in secondary growth.
    [Show full text]
  • Chapter 36 Transport in Vascular Plants Lecture Outline
    Chapter 36 Transport in Vascular Plants Lecture Outline Overview: Pathways for Survival The algal ancestors of plants obtained water, minerals and CO2 from the water in which they were completely immersed. For vascular plants, the evolutionary journey onto land involved the differentiation of the plant body into roots, which absorb water and minerals from the soil, and shoots, which absorb light and atmospheric CO2 for photosynthesis. This morphological solution created a new problem: the need to transport materials between roots and shoots. Xylem transports water and minerals from the roots to the shoots. Phloem transports sugars from the site of production to the regions that need them for growth and metabolism. Concept 36.1 Physical forces drive the transport of materials in plants over a range of distances Transport in plants occurs on three levels: 1. The uptake and loss of water and solutes by individual cells, such as root hairs. 2. Short-distance transport of substances from cell to cell at the level of tissues or organs, such as the loading of sugar from photosynthetic leaf cells into the sieve tubes of phloem. 3. Long-distance transport of sap within xylem and phloem at the level of the whole plant. Transport at the cellular level depends on the selective permeability of membranes. The selective permeability of a plant cell’s plasma membrane controls the movement of solutes between the cell and the extracellular solution. Molecules tend to move down their concentration gradient. Diffusion across a membrane is called passive transport and occurs without the direct expenditure of metabolic energy by the cell.
    [Show full text]
  • Biol 695 Plant Water Relationships Chapter 4
    BIOL 695 PLANT WATER RELATIONSHIPS CHAPTER 4 Mengel et al., 5th Ed WATER POTENTIAL - 1 µ - µº Y = w w vw Y = water potential µw = chem potential of water in system µ°w = chem potential of pure free water Vw = partial molar vol of water in system Units for water potential - kPa or Mpa Pa = Pascal 1 bar = 105 Pa WATER POTENTIAL - 2 Y = yp + ys + ym yp - pressure potential = hydrostatic pressure - positive ys - osmotic potential - effect of solutes - negative ym - matric potential - capillarity and adsorption effects - negative Gradient in Water Potential • Potential of Pure Free Water = 0 • Potential in plants < 0 (-0.1 - -1.5 MPa) • Gradient during day (stomata open) – atmosphere >> leaf cells > xylem sap > root cells > external solution Gradient in Water Potential • Water potential, Y , represents driving force for water transfer in cells, tissues, whole plants • Water movement is function of potential difference and resistance to flow • Resistance from cell walls, membranes, cuticles, etc. F = Y 1 - Y 2 R Y 1, Y 2 = water potential at two points F = flow rate R = resistance OSMOSIS Semi permeable membrane Semi permeable membrane a) b) High Low Low High Water potential Turgor a) net H2O movement-high to low Y Water molecule- b) equilib. Between both H2O Y / Sucrose molecule - high turgor in sucrose sol’n / no net water movement OSMOTIC POTENTIAL 0 Water potential -10 Y = y p + y s -20 r a +10 b l, a ti Turgor, hydrostatic pressure n +5 te y o p P 0 -10 Osmotic potential -15 y s -20 Relative cell volume 1.0 1.5 Flaccid Fully turgid OSMOSIS
    [Show full text]
  • How Does Water Move Through Plants to Get to the Top Of
    http://www.nature.com/scitable/knowledge/library/water-uptake-and-tra... By: Andrew J. McElrone (U.S. Department of Agriculture, Agricultural Research Service, University of California, Davis), Brendan Choat (University of Western Sydney), Greg A. Gambetta (University of California, Davis) & Craig R. Brodersen (University of Florida) © 2013 Nature Education Citation: McElrone, A. J., Choat, B., Gambetta, G. A. & Brodersen, C. R. (2013) Water Uptake and Transport in Vascular Plants. Nature Education Knowledge 4(5):6 How does water move through plants to get to the top of tall trees? Here we describe the pathways and mechanisms driving water uptake and transport through plants, and causes of flow disruption. Why Do Plants Need So Much Water? Water is the most limiting abiotic (non-living) factor to plant growth and productivity, and a principal determinant of vegetation distributions worldwide. Since antiquity, humans have recognized plants' thirst for water as evidenced by the existence of irrigation systems at the beginning of recorded history. Water's importance to plants stems from its central role in growth and photosynthesis, and the distribution of organic and inorganic molecules. Despite this dependence, plants retain less than 5% of the water absorbed by roots for cell expansion and plant growth. The remainder passes through plants directly into the atmosphere, a process referred to as transpiration. The amount of water lost via transpiration can be incredibly high; a single irrigated corn plant growing in Kansas can use 200 L of water during a typical summer, while some large rainforest trees can use nearly 1200 L of water in a single day! If water is so important to plant growth and survival, then why would plants waste so much of it? The answer to this question lies in another process vital to plants — photosynthesis.
    [Show full text]
  • Xylem Hydraulics and the Soil–Plant–Atmosphere Continuum: Opportunities and Unresolved Issues
    Xylem Hydraulics and the Soil–Plant–Atmosphere Continuum: Opportunities and Unresolved Issues John S. Sperry,* Volker Stiller, and Uwe G. Hacke ABSTRACT about the hydraulic properties of the plant vascular sys- Soil and xylem are similar hydraulically. An unsaturated conductiv- tem. The traditional view of plant hydraulics being dom- ity curve for soil is called a vulnerability curve for xylem—but the inated by resistances of endodermis and root cortex underlying physical basis is the same. Thus, any transport model that (Boyer, 1985; Philip, 1966) is expanding to include well treats unsaturated soil conductivity would benefit by also incorporat- documented and surprisingly dynamic responses of xy- ing the analogous xylem vulnerability curves. This is especially the lem flow resistance to environment. The behavior of case for crop plants, which as a group have relatively vulnerable xylem. water in soil and xylem is strikingly identical, making it Although the cohesion–tension mechanism for xylem transport has possible to model xylem flow with the same quantitative withstood recent challenges, a number of gaps remain in our under- precision as soil flow. The result is an opportunity for standing of xylem hydraulics. These include the extent and mechanism SPAC models to incorporate more mechanistic and pre- of cavitation reversal and thus hysteresis in the vulnerability curve, the structural basis for differences in air entry pressure (ϭcavitation dictive treatment of plant hydraulics and a better under- pressure) for different xylem types, a quantitative model of xylem standing of how the SPAC is influenced by drought conductivity, and a mechanistic understanding of how stomata regu- cycles.
    [Show full text]
  • A Survey of Root Pressure in 53 Asian Species of Bamboo Wang, Tian, Ding, Wan, M
    A survey of root pressure in 53 Asian species of bamboo Wang, Tian, Ding, Wan, M. Tyree To cite this version: Wang, Tian, Ding, Wan, M. Tyree. A survey of root pressure in 53 Asian species of bamboo. Annals of Forest Science, Springer Nature (since 2011)/EDP Science (until 2010), 2011, 68 (4), pp.783-791. 10.1007/s13595-011-0075-1. hal-00930808 HAL Id: hal-00930808 https://hal.archives-ouvertes.fr/hal-00930808 Submitted on 1 Jan 2011 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. Annals of Forest Science (2011) 68:783–791 DOI 10.1007/s13595-011-0075-1 ORIGINAL PAPER A survey of root pressure in 53 Asian species of bamboo Fusheng Wang & Xinli Tian & Yulong Ding & Xianchong Wan & M. T. Tyree Received: 4 October 2010 /Accepted: 4 January 2011 /Published online: 1 June 2011 # INRA and Springer Science+Business Media B.V. 2011 Abstract is comparatively rare. Xylem exudate and guttation fluid & Introduction Root pressure is a potentially important had an osmotic pressure greater than root pressure and this mechanism for dissolving embolisms in previously cavitat- can be explained in terms of a low reflection coefficient in ed vessels, but the occurrence of root pressure is not a context of how root pressure is generated according to the universal property in plants.
    [Show full text]