維管植物的運(yùn)輸課件

1、Chapter 36Transport in Vascular Plants維管植物的運(yùn)輸Overview: Pathways for Survival of vascular plant (維管植物存活途徑)For vascular plants, the evolutionary journey (演化之旅) onto land involved the differentiation of the plant body into roots and shoots (植物體分化為根與枝條)Vascular tissue transports nutrients throughout a p

2、lant; such transport may occur over long distances (長途運(yùn)輸)Figure 36.1Key ConceptsConcept 36.1: Physical forces drive the transport of materials in plants over a range of distancesConcept 36.2: Roots absorb water and minerals from the soilConcept 36.3: Water and minerals ascend from roots to shoots th

3、rough xylem (木質(zhì)部)Concept 36.4: Stomata help regulate the rate of transpiration (蒸散作用)Concept 36.5: Organic nutrients are translocated through the phloem (韌皮部)Concept 36.1: Physical forces drive the transport of materials in plants over a range of distancesTransport in vascular plants occurs on three

4、 scales (三種尺度/三種層次)Transport of water and solutes by individual cells, such as root hairs (個(gè)別細(xì)胞水與溶質(zhì)的運(yùn)輸)Short-distance transport of substances from cell to cell at the levels of tissues and organs (組織與器官內(nèi)細(xì)胞間物質(zhì)的短距離運(yùn)輸)Long-distance transport within xylem and phloem at the level of the whole plant (整株植物

5、木質(zhì)部與韌皮部的長距離運(yùn)輸)A variety of physical processes (物理過程) are involved in the different types of transport (眾 多物理過程介入或參與不同型式的運(yùn)輸)Figure 36.2MineralsH2OCO2O2CO2O2H2OSugarLight Sugars are produced byphotosynthesis in the leaves.5 Sugars are transported asphloem sap to roots and otherparts of the plant.6 Thr

6、ough stomata, leaves take in CO2 and expel O2. The CO2 provides carbon forphotosynthesis. Some O2 produced by photosynthesis is used in cellular respiration.4Transpiration, the loss of waterfrom leaves (mostly throughstomata), creates a force withinleaves that pulls xylem sap upward.3 Water and mine

7、rals aretransported upward fromroots to shoots as xylem sap.2 Roots absorb waterand dissolved mineralsfrom the soil.1 Roots exchange gases with the air spaces of soil, taking in O2 and discharging CO2. In cellular respiration, O2 supports the breakdown of sugars.7(木質(zhì)液)(木質(zhì)液)(蒸散作用)(韌皮液)Selective Perme

8、ability of Membranes: A Review膜的選擇通透性-各種膜系統(tǒng)The selective permeability (選擇通透性) of a plant cells plasma membrane (細(xì)胞膜)Controls the movement of solutes into and out of the cellSpecific transport proteins/transportor (專一性輸送蛋白)Enable plant cells to maintain an internal environment different from their su

9、rroundingsSolutes in cell: cation (陽離子), anion (陰離子), neutral solute (中性溶質(zhì))The Central Role of Proton Pumps (質(zhì)子唧筒)Proton pumps (質(zhì)子唧筒) in plant cellsCreate a hydrogen ion gradient (氫離子梯度) that is a form of potential energy (潛能) that can be harnessed (=used) to do work (作功)Contribute to a voltage know

10、n as a membrane potential (膜電位), also a kind of potential energyFigure 36.3CYTOPLASMEXTRACELLULAR FLUIDATPH+H+H+H+H+H+H+H+Proton pump generates membrane potentialand H+ gradient.+Proton pump細(xì)胞質(zhì)細(xì)胞外液Plant cells use energy stored in the proton gradient (氫離子梯度) and membrane potential (膜電位), both of whic

11、h are potential energyTo drive the transport of many different solutesFigure 36.4a+CYTOPLASMEXTRACELLULAR FLUIDCations ( , for example) are driven into the cell by themembrane potential.Transport protein(transportor)K+K+K+K+K+K+K+K+(a) Membrane potential and cation uptake (陽離子的吸收)+transporter細(xì)胞質(zhì)細(xì)胞外液

12、In the mechanism called cotransport (共同運(yùn)輸)A transport protein (cotransporter) couples the passage of one solute to the passage of anotherFigure 36.4bH+H+H+H+H+H+H+H+H+H+H+H+NO3 NO3 NO3 NO3 NO3 NO3 +NO3(b) Cotransport of anions (陰離子的共同運(yùn)輸)H+of through acotransporter.Cell accumulates anions ( , for exa

13、mple) by coupling their transport to theinward diffusion 共同運(yùn)輸?shù)鞍赘邼舛菻+低濃度NO3-低濃度H+高濃度NO3-cotransporter細(xì)胞質(zhì)細(xì)胞外液Figure 36.4cThe “coattail” effect of cotransport (共同運(yùn)輸)Is also responsible for the uptake of the sugar sucrose (neutral solute) by plant cellsH+H+H+H+H+H+H+H+H+H+SSSSSPlant cells canalso accumu

14、late a neutral solute,such as sucrose( ), bycotransporting down thesteep protongradient.SH+H+H+S+(c) Cotransport of a neutral solute (中性溶質(zhì)的共同運(yùn)輸)cotransporter細(xì)胞外液細(xì)胞質(zhì)低濃度H+高濃度sugar高濃度H+低濃度sugar報(bào)告完畢敬請(qǐng)指教！？?。浚?？??？??？??？Effects of Differences in Water Potential水勢差的效應(yīng)To survive plants must balance water uptake

15、 and lossDifferences in water potential drive water transport in plant cells (水勢差驅(qū)動(dòng)植物細(xì)胞中的水份運(yùn)輸)Osmosis (滲透作用)Determines the net uptake or water loss by a cellIs affected by solute concentration and pressureOsmotic pressure (滲透壓) in animal cellslow osmotic pressure=low solute=high waterhigh osmotic pr

16、essure=high solute=low waterDirection of moving water low osmotic pressure=low solute=high waterhigh osmotic pressure=high solute=low waterIsotonic solution(等張溶液)、 hypertonic solution(高張溶液)、 hypotonic solution(低張溶液)watersolutewaterWater potential (水勢)Is a measurement that combines the effects of sol

17、ute concentration and pressureDetermines the direction of movement of waterWaterFlows from regions of high water potential to regions of low water potentialSolute (溶質(zhì))WaterSoluteInOutMembraneHow Solutes and Pressure Affect Water PotentialBoth pressure and solute concentrationAffect water potentialTh

18、e solute potential of a solutionIs proportional to the number of dissolved moleculesPressure potentialIs the physical pressure on a solutionQuantitative Analysis of Water Potential (水勢)The addition of solutes reduces water potentialFigure 36.5a0.1 MsolutionH2OPurewaterP = 0S = 0.23 = 0.23 MPa = 0 MP

19、a(a)High solute=Low water potentialLow solute=High water potentialApplication of physical pressure (物理性壓力)Increases water potential (水勢)H2OP = 0.23S = 0.23 = 0 MPa = 0 MPa(b)H2OP = 0.30S = 0.23 = 0.07 MPa = 0 MPa(c)Figure 36.5b, cNegative pressure (負(fù)壓)Decreases water potentialH2OP = 0S = 0.23 = 0.23

20、 MPa(d)P = 0.30S = 0 = 0.30 MPaFigure 36.5dWater potential (水勢)Affects uptake and loss of water by plant cellsIf a flaccid cell (鬆弛細(xì)胞) is placed in an environment with a higher solute concentrationThe cell will lose water and become plasmolyzed (膜壁分離)Figure 36.6a0.4 M sucrose solution:Initial flacci

21、d cell:Plasmolyzed cellat osmotic equilibriumwith its surroundingsP = 0S = 0.7P = 0S = 0.9P = 0S = 0.9 = 0.9 MPa = 0.7 MPa = 0.9 MPaIf the same flaccid cell is placed in a solution with a lower solute concentrationThe cell will gain water and become turgid (膨脹)Distilled water:Initial flaccid cell:Tu

22、rgid cellat osmotic equilibriumwith its surroundingsP = 0S = 0.7P = 0S = 0P = 0.7S = 0.7Figure 36.6b = 0.7 MPa = 0 MPa = 0 MPaTurgor (膨壓) loss in plants causes wilting (萎凋)Which can be reversed when the plant is watered (澆水)Figure 36.7報(bào)告完畢敬請(qǐng)指教??？??？??？?。浚。浚。緼quaporin Proteins and Water TransportAquapor

23、ins (水孔蛋白)Are transport proteins (運(yùn)轉(zhuǎn)蛋白) in the cell membrane that allow the passage of waterDo not affect water potentialThree Major Compartments (區(qū)間) of Vacuolated Plant CellsTransport is also regulatedBy the compartmental structure of plant cellsCompartmentation (區(qū)間化/區(qū)隔化/間隔化)Cell wall (細(xì)胞壁)Cytosol

24、 (細(xì)胞質(zhì)液)Vacuole (液胞)The plasma membrane (細(xì)胞膜) Directly controls the traffic of molecules into and out of the protoplastIs a barrier between two major compartments (區(qū)間), the cell wall and the cytosolCell compartments (細(xì)胞間隔) ：同一細(xì)胞內(nèi)The third major compartment in most mature plant cells is the vacuole, a

25、 large organelle that can occupy as much as 90% of more of the protoplasts volume The vacuolar membrane (液胞膜) regulates transport between the cytosol and the vacuoleFigure 36.8aTransport proteins in the plasma membrane regulate traffic of molecules between the cytosol and the cell wall.Transport pro

26、teins inthe vacuolar membrane regulate traffic of molecules between the cytosol and the vacuole.3. Plasmodesma(細(xì)胞質(zhì)連絡(luò)絲)1. Vacuolar membrane(tonoplast) (液胞膜)2. Plasma membraneCell wallCytosolVacuoleCell compartments. The cell wall, cytosol, and vacuole are the three maincompartments of most mature pla

27、nt cells.(a)Three compartmentsIn most plant tissuesThe cell walls and cytosol are continuous from cell to cellThe cytoplasmic continuumIs called the symplast (共質(zhì)體/合胞體)The apoplast (離質(zhì)體/非原質(zhì)體/質(zhì)外體)Is the continuum of cell walls plus extracellular spacesTissue compartments (組織間隔) ：不同細(xì)胞間Figure 36.8bKeySy

28、mplastApoplastThe symplast is thecontinuum ofcytosol connectedby plasmodesmata.The apoplast isthe continuumof cell walls andextracellularspaces.Apoplast1. Transmembrane route2. Symplastic route3. Apoplastic routeSymplastTransport routes between cells. At the tissue level, there are three passages: t

29、he transmembrane, symplastic, and apoplastic routes. Substances may transfer from one route to another.(b)(共質(zhì)體途徑)(質(zhì)外體途徑)(質(zhì)外體)(共質(zhì)體)(穿越細(xì)胞膜途徑)Functions of the Symplast and Apoplast in TransportWater and minerals can travel through a plant by one of three routesOut of one cell, across a cell wall, and i

30、nto another cellVia the symplast (共質(zhì)體/合胞體)Along the apoplast (離質(zhì)體/非原質(zhì)體/質(zhì)外體)Bulk Flow in Long-Distance Transport長距離運(yùn)輸?shù)木蘖鱅n bulk flow (巨流)Movement of fluid (sap) in the xylem and phloem is driven by pressure differences (壓力差) at opposite ends of the xylem vessels (木質(zhì)部導(dǎo)管) and phloem sieve tubes (韌皮部篩管)

31、報(bào)告完畢敬請(qǐng)指教?。浚?？！？！？?。浚?？Concept 36.2: Roots absorb water and minerals from the soilWater and mineral salts (礦物鹽) from the soilEnter the plant through the epidermis of roots and ultimately flow to the shoot systemLateral transport (側(cè)向運(yùn)輸) of minerals and water in rootsFigure 36.9卡氏帶維管束導(dǎo)管(1) Uptake of soil

32、 solution by the hydrophilic walls of root hairs provides access to the apoplast. Water and minerals can then soak into the cortex along this matrix of walls.(2) Minerals and water that crossthe plasma membranes of roothairs enter the symplast.(3) As soil solution moves alongthe apoplast, some water

33、 andminerals are transported intothe protoplasts of cells of theepidermis and cortex and thenmove inward via the symplast.(4) Within the transverse and radial walls of each endodermal cell is the Casparian strip, a belt of waxy material (purple band) that blocks the passage of water and dissolved mi

34、nerals. Only minerals already in the symplast or entering that pathway by crossing the plasma membrane of an endodermal cell can detour around the Casparian strip and pass into the vascular cylinder.(5) Endodermal cells and also parenchyma cells within thevascular cylinder discharge water and minera

35、ls into theirwalls (apoplast). The xylem vessels transport the waterand minerals upward into the shoot system.Casparian stripPathway along apoplast Pathway throughsymplastPlasmamembraneApoplasticrouteSymplasticrouteRoot hairEpidermisCortexEndodermisVascular cylinderVessels(xylem)Casparian stripEndod

36、ermal cell卡氏帶(共質(zhì)體途徑)(質(zhì)外體途徑)(共質(zhì)體途徑)(質(zhì)外體途徑)345表皮皮層內(nèi)皮4512The Roles of Root Hairs, Mycorrhizae, and Cortical CellsMuch of the absorption of water and minerals occurs near root tips, where the epidermis is permeable to water and where root hairs are locatedRoot hairs account for much of the surface area

37、of rootsMost plants form mutually beneficial relationships (互利共生) with fungi, which facilitate (促進(jìn)) the absorption of water and minerals from the soilRoots and fungi form mycorrhizae (菌根), symbiotic structures(共生結(jié)構(gòu)) consisting of plant roots united with fungal hyphae (菌絲)Figure 36.102.5 mm菌根是真菌與根的共生

38、結(jié)合Once soil solution enters the rootsThe extensive surface area of cortical cell membranes enhances uptake of water and selected mineralsThe Endodermis: A Selective Sentry (選擇性進(jìn)入)The endodermis (內(nèi)皮層)Is the innermost layer (最內(nèi)層) of cells in the root cortexSurrounds the vascular cylinder and functions

39、 as the last checkpoint (最後關(guān)卡) for the selective passage of minerals from the cortex (皮質(zhì)) into the vascular tissue (維管束組織)Water can cross the cortex (皮層)Via the symplastic (共質(zhì)體的) or apoplastic route (質(zhì)外體的路徑) The waxy Casparian strip (卡氏帶) of the endodermal wall (內(nèi)皮細(xì)胞壁)Blocks apoplastic transfer of m

40、inerals from the cortex to the vascular cylinder報(bào)告完畢敬請(qǐng)指教??？?。浚?？?。浚。浚?？Concept 36.3: Water and minerals ascend (升高) from roots to shoots through the xylemPlants lose an enormous amount of water through transpiration, the loss of water vapor from leaves and other aerial parts of the plantThe transpired

41、water must be replaced by water transported up from the rootsMineralsH2OCO2O2CO2O2H2OSugarLightFactors Affecting the Ascent of Xylem SapXylem sap (木質(zhì)部汁液)Rises to heights of more than 100 m in the tallest plantsPushing Xylem Sap: Root Pressure (根壓)At night, when transpiration is very lowRoot cells co

42、ntinue pumping mineral ions into the xylem of the vascular cylinder, lowering the water potentialWater flows in from the root cortex (根的皮層)Generating root pressure (根壓) in the xylem Root pressure (根壓) sometimes results in guttation (點(diǎn)泌作用), the exudation (滲出作用) of water droplets (小水滴) on tips of gras

43、s blades or the leaf margins (葉緣) of some small, herbaceous eudicots (草本的真雙子葉植物)Figure 36.11報(bào)告完畢敬請(qǐng)指教！？?。浚?？?。浚。浚?？Pulling Xylem Sap: The Transpiration-Cohesion-Tension Mechanism (拉升木質(zhì)液：蒸散作用內(nèi)聚力-附著力-張力的作用機(jī)制)Water is pulled upward by negative pressure (負(fù)壓) in the xylemTranspirational Pull (蒸散作用的拉力)Water

44、vapor in the airspaces of a leafDiffuses down its water potential gradient and exits the leaf via stomataTranspiration produces negative pressure (tension) in the leaf which exerts a pulling force (拉力) on water in the xylem, pulling water into the leaf Evaporation causes the air-water interface to r

45、etreat farther into the cell wall and become more curved as the rate of transpiration increases. As the interface becomes more curved, the water films pressure becomes more negative. This negative pressure, or tension, pulls water from the xylem, where the pressure is greater.CuticleUpper epidermisM

46、esophyllLower epidermisCuticleWater vaporCO2O2XylemCO2O2Water vaporStomaEvaporation At first, the water vapor lost bytranspiration is replaced by evaporation from the water film that coats mesophyll cells. In transpiration, water vapor (shown as blue dots) diffuses from the moist air spaces of the l

47、eaf to the drier air outside via stomata. AirspaceCytoplasmCell wallVacuoleEvaporationWater filmLow rate oftranspirationHigh rate oftranspirationAir-water interfaceCell wallAirspaceY = 0.15 MPaY = 10.00 MPa312Figure 36.12Air-spaceCohesion and Adhesion in the Ascent of Xylem Sap (木質(zhì)液上升時(shí)的凝聚力與附著力) The

48、transpirational pull (蒸散作用拉力) on xylem sapIs transmitted (傳導(dǎo)/傳遞) all the way from the leaves to the root tips and even into the soil solutionIs facilitated by cohesion and adhesion (凝聚力與附著力)水份在樹木中的上升作用Ascent of xylem sap (木質(zhì)液的上升)Xylem sapOutside air Y = 100.0 MPaLeaf Y (air spaces)= 7.0 MPaLeaf Y (c

49、ell walls)= 1.0 MPaTrunk xylem Y= 0.8 MPaWater potential gradientRoot xylem Y= 0.6 MPaSoil Y= 0.3 MPaMesophyll cellsStomaWater moleculeAtmosphereTranspirationXylemcellsAdhesionCell wallCohesion, by hydrogenbondingWater moleculeRoot hairSoil particleWaterCohesion and adhesionin the xylemWater uptakef

50、rom soil Figure 36.13水勢梯度Xylem Sap Ascent by Bulk Flow: A ReviewThe movement of xylem sap (木質(zhì)液) against gravity (重力/萬有引力)Is maintained by the transpiration-cohesion-tension mechanism報(bào)告完畢敬請(qǐng)指教！？??？?。浚?？??？?。縏he central role of stomataConcept 36.4: Stomata help regulate the rate of transpiration (氣孔協(xié)助調(diào)控蒸散

51、速率)Leaves generally have broad surface areas and high surface-to-volume ratios (表面積/體積比)Both of these characteristicsIncrease photosynthesisIncrease water loss through stomata20 mFigure 36.14Effects of Transpiration on Wilting and Leaf Temperature (蒸散作用對(duì)萎凋與葉溫的影響)Plants lose a large amount of water b

52、y transpirationIf the lost water is not replaced by absorption through the rootsThe plant will lose water and wiltTranspiration also results in evaporative cooling (蒸發(fā)冷卻效應(yīng))Which can lower the temperature of a leaf and prevent the denaturation of various enzymes involved in photosynthesis and other m

53、etabolic processesStomata: Major Pathways for Water LossAbout 90% of the water a plant losesEscapes through stomataGuard cells (保衛(wèi)細(xì)胞)Each stoma is flanked by guard cells which control the diameter of the stoma by changing shapeCells flaccid/Stoma closed細(xì)胞鬆弛/氣孔關(guān)閉Cells turgid/Stoma open細(xì)胞膨脹/氣孔打開Radial

54、ly oriented cellulose microfibrilsCellwallVacuoleGuard cell(a) Changes in guard cell shape and stomatal opening and closing (surface view). Guard cells of a typical angiosperm are illustrated in their turgid (stoma open) and flaccid (stoma closed) states. The pair of guard cells buckle outward (向外彎曲

55、) when turgid. Cellulose microfibrils in the walls resist stretching and compression in the direction parallel to the microfibrils. Thus, the radial orientation of the microfibrils causes the cells to increase in length more than width when turgor increases. The two guard cells are attached at their

56、 tips, so the increase in length causes buckling.Figure 36.15aChanges in turgor pressure (膨壓) that open and close stomataResult primarily from the reversible uptake and loss of potassium (K+) ions by the guard cells(b) Role of potassium in stomatal opening and closing. The transport of K+ (potassium

57、 ions, symbolized here as red dots) across the plasma membrane and vacuolar membrane causes the turgor changes of guard cells.H2OH2OH2OH2OH2OK+H2OH2OH2OH2OH2OFigure 36.15bXerophyte Adaptations That Reduce Transpiration旱生植物減少蒸散作用以適應(yīng)環(huán)境Xerophytes (旱生植物)Are plants adapted to arid climates (乾旱氣候)Have var

58、ious leaf modifications (葉的變形) that reduce the rate of transpirationThe stomata of xerophytes (旱生植物的氣孔)Are concentrated on the lower leaf surface (下表皮)Are often located in depressions that shelter the pores from the dry windFigure 36.16Lower epidermaltissueTrichomes(“hairs”)細(xì)毛CuticleUpper epidermal

59、tissueStomata100 m下表皮上表皮Concept 36.5: Organic nutrients are translocated (轉(zhuǎn)移/運(yùn)移) through the phloemTranslocation (轉(zhuǎn)移/運(yùn)移)Is the transport of organic nutrients in the plantPhloem sap (韌皮液)Is an aqueous solution that is mostly sucroseTravels from a sugar source to a sugar sink Phloem sap (韌皮液)Is an aqu

60、eous solution that is mostly sucroseTravels from a sugar source to a sugar sinkA sugar source (糖的源頭)Is a plant organ that is a net producer of sugar, such as mature leavesA sugar sink (糖的儲(chǔ)存區(qū))Is an organ that is a net consumer or store of sugar, such as a tuber or bulbMovement from Sugar Sources to S