维管植物的运输课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,2020年5月29日星期五,#,27 十一月 2024,维管植物的运输,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 plant; such transport may occur over long distances,(長途運輸),Figure 36.1,Key Concepts,Concept 36.1:,Physical forces,drive the transport of materials in plants over a range of distances,Concept 36.2:,Roots,absorb water and minerals from the soil,Concept 36.3:,Water and minerals ascend from roots to shoots through,xylem (,木質部,),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 distances,Transport in vascular plants occurs on,three scales,(三種尺度/三種層次),Transport of water and solutes by,individual cells, such as root hairs,(個別細胞水與溶質的運輸),Short-distance transport,of substances from cell to cell at the levels of tissues and organs,(組織與器官內細胞間物質的短距離運輸),Long-distance transport,within,xylem and phloem,at the level of the whole plant,(整株植物木質部與韌皮部的長距離運輸),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輸),Figure 36.2,Minerals,H,2,O,CO,2,O,2,CO,2,O,2,H,2,O,Sugar,Light,Sugars,are produced by,photosynthesis in the leaves.,5,Sugars are transported as,phloem sap,to roots and other,parts of the plant.,6,Through,stomata, leaves take in CO,2,and expel O,2,. The CO,2,provides carbon for,photosynthesis. Some O,2,produced by photosynthesis is used in cellular respiration.,4,Transpiration, the loss of water,from leaves (mostly through,stomata), creates a force within,leaves that pulls,xylem sap,upward.,3,Water and minerals are,transported,upward,from,roots to shoots as,xylem sap,.,2,Roots,absorb water,and dissolved minerals,from the soil.,1,Roots exchange gases,with the air spaces of soil,taking in O,2,and discharging,CO,2,. In cellular respiration,O,2,supports the breakdown,of sugars.,7,(木質液),(木質液),(蒸散作用),(韌皮液),Selective Permeability of Membranes:,A Review,膜的選擇通透性-各種膜系統,The selective permeability,(,選擇通透性,),of a plant cells plasma membrane,(,細胞膜,),Controls the movement of solutes into and out of the cell,Specific transport proteins/transportor,(專一性輸送蛋白),Enable plant cells to maintain an internal environment different from their surroundings,Solutes in cell: cation (陽離子), anion (陰離子), neutral solute (中性溶質),The Central Role of Proton Pumps,(質子唧筒),Proton pumps,(質子唧筒),in plant cells,Create 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 known as a,membrane potential,(膜電位),also a kind of potential energy,Figure 36.3,CYTOPLASM,EXTRACELLULAR FLUID,ATP,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,Proton pump generates,membrane potential,and,H,+,gradient.,+,+,+,+,+,Proton pump,細胞質,細胞外液,Plant cells use energy stored in the,proton gradient,(氫離子梯度),and,membrane potential,(膜電位,), both of which are,potential energy,To drive the transport of many different solutes,Figure 36.4a,+,CYTOPLASM,EXTRACELLULAR FLUID,Cations ( , 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,細胞質,細胞外液,In the mechanism called,cotransport,(共同運輸),A,transport protein,(cotransporter),couples the passage of one solute to the passage of another,Figure 36.4b,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,NO,3,NO,3,NO,3,NO,3,NO,3,NO,3,+,+,+,+,+,+,NO,3,(b) Cotransport of anions,(陰離子的共同運輸),H,+,of through a,cotransporter.,Cell accumulates,anions (, for,example) by,coupling their transport to theinward diffusion,共同運輸蛋白,高濃度H,+,低濃度NO,3,-,低濃度H,+,高濃度NO,3,-,cotransporter,細胞質,細胞外液,Figure 36.4c,The “coattail” effect of cotransport,(共同運輸),Is also responsible for the uptake of the sugar,sucrose,(neutral solute) by plant cells,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,H,+,S,S,S,S,S,Plant cells can,also accumulate a,neutral solute,such as,sucrose,( ),by,cotransporting,down the,steep proton,gradient.,S,H,+,+,+,+,+,+,H,+,H,+,S,+,(c) Cotransport of a neutral solute,(中性溶質的,共同運輸,),cotransporter,細胞外液,細胞質,低濃度H,+,高濃度sugar,高濃度H,+,低濃度sugar,報告完畢,敬請指教,！？,！？,！？,！？,！？,！？,Effects of Differences in Water Potential水勢差的效應,To survive plants must balance water uptake and loss,Differences in,water potential,drive water transport in plant cells (,水勢差,驅動植物細胞中的水份運輸),Osmosis,(滲透作用),Determines the net uptake or water loss by a cell,Is affected by solute concentration and pressure,Osmotic pressure (滲透壓) in animal cells,low osmotic pressure=low solute=high water,high osmotic pressure=high solute=low water,Direction of moving water,low osmotic,pressure,=,low solute=,high water,high osmotic pressure,=,high solute=,low water,Isotonic solution(等張溶液)、,hypertonic solution(高張溶液)、,hypotonic solution(低張溶液),water,solute,water,Water potential,(水勢),Is a measurement that combines the effects of,solute concentration and pressure,Determines the direction of movement of water,Water,Flows from regions of,high water potential,to regions of,low water potential,Solute,(,溶質,),Water,Solute,In,Out,Membrane,How Solutes and Pressure Affect Water Potential,Both pressure and solute concentration,Affect water potential,The,solute potential,of a solution,Is proportional to the number of dissolved molecules,Pressure potential,Is the physical pressure on a solution,Quantitative Analysis of Water Potential,(水勢),The addition of solutes reduces water potential,Figure 36.5a,0.1,M,solution,H,2,O,Pure,water,P,= 0,S,= 0.23,= 0.23 MPa,= 0 MPa,(a),High solute,=Low water potential,Low solute,=High water potential,Application of,physical pressure,(物理性壓力),Increases,water potential,(水勢),H,2,O,P,= 0.23,S,= 0.23,= 0 MPa,= 0 MPa,(b),H,2,O,P,= 0.30,S,= 0.23,= 0.07 MPa,= 0 MPa,(c),Figure 36.5b, c,Negative pressure,(負壓),Decreases water potential,H,2,O,P,= 0,S,= 0.23,= 0.23 MPa,(d),P,= 0.30,S,= 0,= 0.30 MPa,Figure 36.5d,Water potential,(水勢),Affects uptake and loss of water by plant cells,If a,flaccid cell,(鬆弛細胞),is placed in an environment with a higher solute concentration,The cell will lose water and become,plasmolyzed,(膜壁分離),Figure 36.6a,0.4,M,sucrose solution:,Initial flaccid cell:,Plasmolyzed cell,at osmotic equilibrium,with its surroundings,P,= 0,S,= 0.7,P,= 0,S,= 0.9,P,= 0,S,= 0.9,=,0.9 MPa,= 0.7 MPa,=,0.9 MPa,If the same,flaccid cell,is placed in a solution with a lower solute concentration,The cell will gain water and become,turgid,(膨脹),Distilled water:,Initial flaccid cell:,Turgid cell,at osmotic equilibrium,with its surroundings,P,= 0,S,= 0.7,P,= 0,S,= 0,P,= 0.7,S,= 0.7,Figure 36.6b,= 0.7 MPa,= 0 MPa,= 0 MPa,Turgor (膨壓),loss in plants causes,wilting (萎凋),Which can be reversed when the plant is watered,(澆水),Figure 36.7,報告完畢,敬請指教,！？,！？,！？,！？,！？,！？,Aquaporin Proteins and Water Transport,Aquaporins,(水孔蛋白),Are,transport proteins,(運轉蛋白),in the cell membrane that allow the passage of water,Do not affect water potential,Three Major Compartments (,區間,) of Vacuolated Plant Cells,Transport is also regulated,By the compartmental structure of plant cells,Compartmentation,(區間化/區隔化/間隔化),Cell wall,(細胞壁),Cytosol,(細胞質液),Vacuole,(液胞),The plasma membrane,(細胞膜),Directly controls the traffic of molecules into and out of the,protoplast,Is a barrier between two major compartments,(區間), the cell wall and the cytosol,Cell compartments (細胞間隔),：同一細胞內,The third major compartment in most mature plant cells is the,vacuole, a 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 vacuole,Figure 36.8a,Transport proteins,in the plasma membrane regulate traffic of molecules between the cytosol and the cell wall.,Transport proteins,in,the vacuolar membrane regulate traffic of molecules between the cytosol and the vacuole.,3. Plasmodesma,(細胞質連絡絲),1. Vacuolar membrane,(tonoplast) (液胞膜),2. Plasma,membrane,Cell wall,Cytosol,Vacuole,Cell compartments. The cell wall, cytosol, and vacuole are the three main,compartments of most mature plant cells.,(a),Three compartments,In most plant tissues,The cell walls and cytosol are continuous from cell to cell,The cytoplasmic continuum,Is called the,symplast (共質體/合胞體),The,apoplast (離質體/非原質體/質外體),Is the continuum of cell walls plus extracellular spaces,Tissue compartments (組織間隔),：不同細胞間,Figure 36.8b,Key,Symplast,Apoplast,The,symplast,is the,continuum of,cytosol connected,by plasmodesmata.,The,apoplast,is,the continuum,of cell walls and,extracellular,spaces.,Apoplast,1. Transmembrane route,2. Symplastic route,3. Apoplastic route,Symplast,Transport routes,between cells. At the tissue level, there are three passages:,the transmembrane, symplastic, and apoplastic routes. Substances may transfer,from one route to another.,(b),(共質體途徑),(質外體途徑),(質外體),(共質體),(穿越細胞膜途徑),Functions of the Symplast and Apoplast in Transport,Water and minerals can travel through a plant by one of three routes,Out of one cell, across a cell wall, and into another cell,Via the symplast,(共質體/合胞體),Along the apoplast,(離質體/非原質體/質外體),Bulk Flow in Long-Distance Transport長距離運輸的巨流,In 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 (木質部導管),and,phloem sieve tubes (韌皮部篩管),報告完畢,敬請指教,！？,！？,！？,！？,！？,！？,Concept 36.2: Roots absorb water and minerals from the soil,Water and mineral salts,(礦物鹽),from the soil,Enter the plant through the epidermis of roots and ultimately flow to the shoot system,Lateral transport (側向運輸) of minerals and water in roots,Figure 36.9,卡氏帶,維管束,導管,(1),Uptake of,soil 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 cross,the,plasma membranes,of root,hairs enter the,symplast,.,(3),As soil solution moves along,the apoplast, some water and,minerals are transported into,the,protoplasts,of cells of the,epidermis and cortex and then,move 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 minerals. 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 the,vascular cylinder discharge water and minerals into their,walls (apoplast). The,xylem vessels,transport the water,and minerals,upward,into the shoot system.,Casparian strip,Pathway along apoplast,Pathway through,symplast,Plasma,membrane,Apoplastic,route,Symplastic,route,Root,hair,Epidermis,Cortex,Endodermis,Vascular,cylinder,Vessels,(xylem),Casparian strip,Endodermal cell,卡氏帶,(共質體途徑),(質外體途徑),(共質體,途徑),(質外體途徑),3,4,5,表皮,皮層,內皮,4,5,1,2,The Roles of Root Hairs, Mycorrhizae, and Cortical Cells,Much of the absorption of water and minerals occurs near,root tips, where the epidermis is,permeable,to water and where root hairs are located,Root hairs,account for much of the surface area of roots,Most plants form,mutually beneficial relationships,(互利共生),with fungi, which,facilitate,(促進),the absorption of water and minerals from the soil,Roots and fungi form,mycorrhizae,(菌根),symbiotic structures,(共生結構),consisting of plant roots united with fungal,hyphae,(菌絲),Figure 36.10,2.5 mm,菌根,是真菌與根的共生結合,Once soil solution enters the roots,The extensive surface area of cortical cell membranes enhances uptake of water and selected minerals,The Endodermis: A Selective Sentry (選擇性進入),The endodermis,(內皮層),Is the innermost layer,(最內層),of cells in the root cortex,Surrounds the vascular cylinder and functions as,the last checkpoint,(最後關卡),for the selective passage of minerals from the cortex,(皮質),into the vascular tissue,(維管束組織),Water can cross the cortex,(皮層),Via the,symplastic,(共質體的),or,apoplastic route (質外體的路徑),The waxy Casparian strip,(卡氏帶),of the endodermal wall (,內皮細胞壁,),Blocks,apoplastic,transfer of minerals from the cortex to the vascular cylinder,報告完畢,敬請指教,！？,！？,！？,！？,！？,！？,Concept 36.3: Water and minerals ascend (,升高,) from roots to shoots through the xylem,Plants lose an enormous amount of water through transpiration, the loss of water vapor from leaves and other aerial parts of the plant,The transpired water must be,replaced by water transported,up from the roots,Minerals,H,2,O,CO,2,O,2,CO,2,O,2,H,2,O,Sugar,Light,Factors Affecting the Ascent of Xylem Sap,Xylem sap,(木質部汁液),Rises to heights of more than 100 m in the tallest plants,Pushing Xylem Sap:,Root Pressure,(根壓),At,night, when transpiration is very low,Root cells continue pumping mineral ions into the xylem of the vascular cylinder, lowering the water potential,Water,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,(點泌作用),the exudation,(滲出作用),of water droplets,(小水滴),on tips of grass blades or the leaf margins,(葉緣),of some small, herbaceous eudicots,(草本的真雙子葉植物),Figure 36.11,報告完畢,敬請指教,！？,！？,！？,！？,！？,！？,Pulling Xylem Sap: The Transpiration-Cohesion-Tension Mechanism,(,拉升木質液,：蒸散作用內聚力-附著力-張力的作用機制),Water is pulled upward by,negative pressure (,負壓,),in the xylem,Transpirational Pull (,蒸散作用的拉力,),Water vapor in the airspaces of a leaf,Diffuses down its,water potential gradient,and exits the leaf via stomata,Transpiration 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 retreat 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.,Cuticle,Upper epidermis,Mesophyll,Lower epidermis,Cuticle,Water vapor,CO,2,O,2,Xylem,CO,2,O,2,Water vapor,Stoma,Evaporation,At first, the water vapor lost by,transpiration 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 leaf to the drier air outside via stomata.,Airspace,Cytoplasm,Cell wall,Vacuole,Evaporation,Water film,Low rate of,transpiration,High rate of,transpiration,Air-water interface,Cell wall,Airspace,Y,= 0.15 MPa,Y,= 10.00 MPa,Figure 36.12,Air-space,Cohesion and Adhesion in the Ascent of Xylem Sap (木質液上升時的凝聚力與附著力),The transpirational pull (,蒸散作用拉力,) on xylem sap,Is,transmitted (,傳導/傳遞,),all the way from the,leaves,to the,root tips,and even into the,soil solution,Is 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,(木質液的上升),Xylem sap,Outside air,Y,= 100.0 MPa,Leaf,Y,(air spaces)= 7.0 MPa,Leaf,Y,(cell walls)= 1.0 MPa,Trunk xylem,Y,= 0.8 MPa,Water potential gradient,Root xylem,Y,= 0.6 MPa,Soil,Y,= 0.3 MPa,Mesophyll cells,Stoma,Water molecule,Atmosphere,Transpiration,Xylem,cells,Adhesion,Cell wall,Cohesion, by hydrogen,bonding,Water molecule,Root hair,Soil particle,Water,Cohesion,and adhesion,in the xylem,Water uptake,from soil,Figure 36.13,水勢梯度,Xylem Sap Ascent by Bulk Flow:,A Review,The movement of xylem sap,(木質液),against,gravity,(重力/萬有引力),Is maintained by the,transpiration-cohesion-tension mechanism,報告完畢,敬請指教,！？,！？,！？,！？,！？,！？,The central role of stomata,Concept 36.4: Stomata help regulate the rate of transpiration,(氣孔協助調控蒸散速率),Leaves generally have,broad surface areas,and,high,surface-to-volume ratios (,表面積/體積比),Both of these characteristics,Increase,photosynthesis,Increase,water loss,through stomata,20 m,Figure 36.14,Effects of Transpiration on Wilting and Leaf Temperature,(蒸散作用對萎凋與葉溫的影響),Plants lose a large amount of water by transpiration,If the lost water is not replaced by absorption through the roots,The plant will lose water and wilt,Transpiration also results in,evaporative cooling (蒸發冷卻效應),Which can lower the temperature of a leaf and prevent the,denaturation of various enzymes,involved in photosynthesis and other metabolic processes,Stomata: Major Pathways for Water Loss,About 90% of the water a plant loses,Escapes through stomata,Guard cells (保衛細胞),Each stoma is flanked by,guard cells,which control the diameter of the stoma by,changing shape,Cells flaccid/,Stoma closed,細胞鬆弛/氣孔關閉,Cells turgid/,Stoma open,細胞膨脹/氣孔打開,Radially oriented,cellulose microfibrils,Cell,wall,Vacuole,Guard 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),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 tips, so the increase in length causes,buckling,.,Figure 36.15a,Changes in,turgor pressure,(膨壓),that open and close stomata,Result 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 ions, symbolized here as red dots) across the plasma membrane and vacuolar membrane causes the,turgor changes,of guard cells.,H,2,O,H,2,O,H,2,O,H,2,O,H,2,O,K,+,H,2,O,H,2,O,H,2,O,H,2,O,H,2,O,Figure 36.15b,Xerophyte Adaptations That Reduce Transpiration旱生植物減少蒸散作用以適應環境,Xerophytes,(,旱生植物,),Are plants adapted to arid climates,(乾旱氣候),Have various leaf modifications,(葉的變形),that reduce the rate of transpiration,The 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 wind,Figure 36.16,Lower,epidermal,tissue,Trichomes,(“hairs”),細毛,Cuticle,Upper,epidermal,tissue,Stomata,100,m,下表皮,上表皮,Concept 36.5: Organic nutrients are translocated,(轉移/運移),through the phloem,Translocation,(轉移/運移),Is the transport of,organic nutrients,in the plant,Phloem sap (韌皮液),Is an aqueous solution that is mostly,sucrose,Travels from a,sugar source,to a,sugar sink,Phloem sap,(韌皮液),Is an aqueous solution that is mostly sucrose,Travels from a sugar source to a sugar sink,A sugar source,(糖的源頭),Is a plant organ that is a net,producer of sugar, such as mature leaves,A sugar sink,(糖的儲存區),Is an organ that is a net,consumer or store of sugar, such as a tuber or bulb,Movement from Sugar Sources to Sugar Sinks,(自糖源頭到糖儲存區的移動),Figure 36.17a,Mesophyll cell,(sugar source),Cell walls,(apoplast),Plasma,membrane,Plasmodesmata,伴細胞,Companion,(transfer) cell,Sieve-tube,Member,(篩管細胞),Mesophyll cell,Phloem,parenchyma cell,Bundle-,sheath cell,(束鞘細胞),(a) Sucrose manufactured in mesophyll cells can travel via the,symplast (blue arrows),to sieve-tube members. In some species, sucrose exits the,symplast (red arrow),near sieve tubes and is actively accumulated from the apoplast by sieve-tube members and their companion cells.,Sugar must be loaded into,sieve-tube members,