The Greening Of Earth - Itbe.hanyang.ac.kr
The Greening of EarthGeneral Biology Looking at a lush landscape it is difficult toimagine the land without any plants or otherorganismsCourse No: BNG2003"Credits: 3.00"""13.1. PlantsProf. Dr. Klaus Heese-CO2 / O2HumidityTemperature AngiospermsSeed plantsGymnospermsPterophyte(ferns, horsetails, whisk fern)MossesHornwortsVascular plantsSeedless vascular plantsLycophytes(club mosses, spike mosses, quillworts)Effect on the environment / ecosystems:Land plantsBryophytes(nonvascular plants)LiverwortsSource for:- Energy (Biofuel Cell, Biomass)- Nutrition- Medicine- ‘IKEA’ Whatever the age of the first land plants, those ancestralspecies gave rise to a vast diversity of modern plants Land plants can be informallygrouped based on the presence orabsence of vascular tissue An overview of land plant evolutionCharophyceansPlants – BioMedical Engineering:Origin of seed plantsOrigin of vascular plantsOrigin of land plantsAncestralgreen alga The general groups of seedless vascular plantsClassification of Seedless Vascular PlantsLYCOPHYTES (PHYLUM LYCOPHYTA)Strobili(clusters ofsporophylls)Isoetesgunnii,a quillwort Seedless vascular plants form two phylaSelaginella apoda,a spike moss– Lycophyta/(e), including club mosses, spike mosses,and quillwortsDiphasiastrum tristachyum, a club mossPTEROPHYTES (PHYLUM PTEROPHYTA)– Pterophyta/(e), including ferns, horsetails, and whiskferns and their relativesPsilotumnudum,a whiskfernAthyriumfilix-femina,lady fernEquisetumarvense,fieldhorsetailVegetative stemStrobilus onfertile stemWHISK FERNS AND RELATIVESHORSETAILSFERNS1
Phylum Lycophyta: Club Mosses, Spike Mosses, and Quillworts Modern species of lycophytes are relics from a far more eminentpast; they are small herbaceous plantsPhylum Pterophyta: Ferns, Horsetails, and Whisk Ferns and Relatives Ferns are the most diverse seedless vascular plantsThe Significance of Seedless Vascular Plants The ancestors of modern lycophytes, horsetails, and ferns grew togreat heights during the Carboniferous, forming the first forestsThe growth of these early forests: may have helped to produce themajor global cooling that characterized the end of the Carboniferousperiod; decayed and eventually became coalSeeds changed the course of plant evolution– enabling their bearers to become the dominantproducers in most terrestrial ecosystems The reduced gametophytes of seed plants are protected inovules and pollen grains In addition to seeds, the following are common to all seedplants– Reduced gametophytes– Heterospory– Ovules– Pollen Living seed plants can be divided into two groups:gymnosperms and angiosperms Gymnosperms bear “naked” seeds, typically on cones Among the gymnosperms are many well-known conifers orcone-bearing trees, including pine, fir, and redwood The gymnosperms include four plant phyla: - Cycadophyta, - Gingkophyta, Gnetophyta, - Coniferophyta Exploring Gymnosperm DiversityPHYLUM CYCADOPHYTAPHYLUM CYCADOPHYTAPHYLUM GINKGOPHYTADouglas firCommon juniperWollemia pinePacificyewCycas revolutaPHYLUM GNETOPHYTAGnetumWelwitschiaSequoiaBristlecone pineOvulate conesEphedraAngiosperms The key reproductive adaptations in the evolution ofangiosperms include flowers and fruits Angiosperms– are commonly known as flowering plants– are seed plants that produce the reproductivestructures called flowers and fruits– are the most widespread and diverse of all plants A flower is a specializedshoot with modified leaves Fruits typically consist of amature ovary– Sepals, which enclosethe flower– Petals, which arebrightly colored andattract pollinators(a) Tomato, a fleshy fruit withsoft outer and inner layersof pericarp(b) Ruby grapefruit, a fleshy fruitwith a hard outer layer andsoft inner layer of pericarp– Stamens, whichproduce pollen– Carpels, which produceovulesCarpelStigmaStamenAnther(c) Nectarine, a fleshyfruit with a soft outerlayer and hard innerlayer (pit) of pericarpStyleOvaryFilamentFlowers The flower is an angiosperm structure specialized forsexual reproductionPetalSepalReceptacle(d) Milkweed, a dry fruit thatsplits open at maturity(e) Walnut, a dry fruit thatremains closed at maturityOvule2
Fruits can be carried by wind, water, or animals tonew locations, enhancing seed dispersal(a)Angiosperm Diversity The two main groups of angiosperms are monocots andeudicotsWings enable maple fruitsto be easily carried by the wind. Basal angiosperms are less derived and include theflowering plants belonging to the oldest lineages Magnoliids share some traits with basal angiosperms butare more closely related to monocots and eudicots(b) Seeds within berries and otheredible fruits are often dispersedin animal feces.(c)The barbs of cocklebursfacilitate seed dispersal byallowing the fruits to“hitchhike” on animals. Exploring Angiosperm DiversityEvolutionary Links Between Angiosperms and d(Lemboglossumfossii)EudicotCharacteristicsBASAL ANGIOSPERMS Pollination of flowers by animals and transport of seeds mbryosTwo cotyledonsVeins usuallynetlikeAmborella trichopodaRootsEudicotsMonocotsAmborellaVascular tissueusually arrangedVascular tissue in ringscatteredLily (Lilium“Enchantment”)Star anise (Illiciumfloridanum)Water lily (Nymphaea“Rene Gerard”)HYPOTHETICAL TREE OF FLOWERING PLANTSStemsMagnoliidsVeins usuallyparallelPygmy date palm(Phoenix roebelenii)– are two important relationships in terrestrialecosystems (ecology / diversity)Pyrenean oak(Quercuspyrenaica)Water liliesLeafvenationStar aniseand relativesOne cotyledonDog rose (Rosa canina), a wild roseRoot systemUsually fibrousTaproot (main root)Barley (Hordeum vulgare),Pea(no main root)usually presenta grass(Lathyrusnervosus,LordPollenAnson’sblue pea), alegumeMAGNOLIIDSPollen grain withPollen grain withthree openingsone openingFlowersAntherFilamentStigmaFloral organs Floral organs usuallyusually inin multiples offour or fiveOvary multiples of threeZucchini(CucurbitaPepo), female(left) andmale flowers(a) A flower pollinated byhoneybees. This honeybee isharvesting pollen and nectar (asugary solution secreted byflower glands) from a Scottishbroom flower. The flower has atripping mechanism that archesthe stamens over the beeand dusts it with pollen, some ofwhich will rub off onto the stigmaof the next flower the bee visits.(b) A flower pollinated by hummingbirds.The long, thin beak and tongue of thisrufous hummingbird enable the animal toprobe flowers that secrete nectar deepwithin floral tubes. Before the hummerleaves, anthers will dust its beak andhead feathers with pollen. Many flowersthat are pollinated by birds are red orpink, colors to which bird eyes areespecially sensitive.(c) A flower pollinated by nocturnal animals. Someangiosperms, such as this cactus, depend mainly onnocturnal pollinators, including bats. Commonadaptations of such plants include large, light-colored,highly fragrant flowers that nighttime pollinators canlocate.Southern magnolia (Magnoliagrandiflora) Human welfare depends greatly on seed plants No two Plants Are Alike No group is more important to human survival thanseed plants To some people the fanwort is an intrusive weed,Products from Seed Plants This plant exhibits plasticity - the ability to alter Humans depend on seedplants forbut to others it is an attractive aquarium plantitself in response to its environment– Food– Wood– Many medicines Threats to Plant Diversity: Destruction of habitat is causingextinction of many plant species and the animal species theysupport In addition to plasticity, entire plant species have by naturalselection accumulated characteristics of morphology thatvary little among plants within the species3
The plant body has a hierarchy of organs, tissues, andcells Plants, like multicellular animals, have organs composed ofdifferent tissues, which are in turn composed of cellsThe Three Basic Plant Organs: Roots, Stems, and Leaves The basic morphology of vascularplants reflects their evolutionaryhistory as terrestrial organismsthat draw nutrients from two verydifferent environments: belowground and above-groundReproductive shoot (flower)Terminal budNodeInternodeTerminalbudRoots Roots are organs that anchor vascular plants; the rootsenable vascular plants to absorb water and nutrients fromthe soil; the roots may have evolved from subterraneanstemsShootsystemVegetativeshootLeaf Three basic organs evolved: roots,stems, and Lateral roots They are organized into a rootsystem and a shoot system Stems: A stem is an organ consisting of an alternatingRoots A root is an organ that anchors the vascular plant; it absorbsminerals and water and it often stores organic nutrients In most plantsthe absorption ofwater andminerals occursnear the roottips, where vastnumbers of tinyroot hairsincrease thesurface area ofthe rootsystem of nodes, the points at which leaves are attached,and of internodes, the stem segments between nodes An axillary budis a structurethat has thepotential to forma lateral shoot,or branch(a)Stolons. Shown here on astrawberry plant, stolonsare horizontal stems that growalong the surface. These “runners”enable a plant to reproduceasexually, as plantlets form atnodes along each runner.Storage leaves(d)(a) Prop roots Many plants havemodified roots(b) Storage roots(d) Buttress roots(c) “Strangling” aerialroots(e) Pneumatophores A terminal budis located nearthe shoot tipand causeselongation of ayoung shootStemRhizomes. The edible baseof this ginger plant is an exampleof a rhizome, a horizontal stemthat grows just below the surfaceor emerges and grows along thesurface.NodeRoot(b)Bulbs. Bulbs are vertical,underground shoots consisting (c)Tubers. Tubers, such as thesemostly of the enlarged basesred potatoes, are enlargedof leaves that store food. Youends of rhizomes specializedcan see the many layers offor storing food. The “eyes”modified leaves attachedarranged in a spiral patternto the short stem by slicing anaround a potato are clustersonion bulb lengthwise.of axillary buds that markthe nodes.See also TCM/oriental medicine:e.g. tubers from Tian MaRhizomeRoot many plants have modified stemsTissue Organization of Stems In gymnosperms and most In most monocot stems theeudicots the vascular tissuevascular bundles are scatteredconsists of vascular bundlesthroughout the ground tissue,arranged in a ringrather than forming a ringPhloemLeavesXylemSclerenchyma(fiber cells)GroundtissueGround tissueconnectingpith to cortex Leaves are organs that increase the surface area of vascularplants, thereby capturing more solar energy for larbundleDermalGround1 mmVascularbundlesVascular1 mm(a) A eudicot stem. A eudicot stem (sunflower), withvascular bundles forming a ring. Ground tissue towardthe inside is called pith, and ground tissue toward theoutside is called cortex. (LM of transverse section)(b) A monocot stem. A monocot stem (maize) with vascularbundles scattered throughout the ground tissue. In such anarrangement, ground tissue is not partitioned into pith andcortex. (LM of transverse section)4
The leaf is the main photosynthetic organ of most vascular Leaves are categorized by two typesplants– Microphylls, leaves with a single vein– Megaphylls, leaves with a highly branched vascularsystem Leaves generally consist of a flattened blade and a stalk aswell as the petiole, which joins the leaf to a node of the stem(a) Simple leaf. A simple leafis a single, undivided blade.Some simple leaves aredeeply lobed, as in anoak leaf. Monocots and dicots differin the arrangement of veins,the vascular tissue of leavesVascular tissuePetiole(b) Compound leaf. In acompound leaf, theblade consists ofmultiple leaflets.Notice that a leaflethas no axillary budat its base.Axillary bud Most monocots have parallel veins Most dicots have branching veins(a)(b)Microphylls, such as those of lycophytes, may haveoriginated as small stem outgrowths supported bysingle, unbranched strands of vascular tissue. In classifying angiosperms,taxonomists may use leafmorphology as a criterionMegaphylls, which have branched vascularsystems, may have evolved by the fusion ofbranched stems.LeafletPetioleAxillary bud(c) Doubly compound leaf.In a doubly compoundleaf, each leaflet isdivided into smallerleaflets.LeafletPetioleAxillary bud Some plant species have evolved modified leaves that servevarious functions(a) Tendrils. The tendrils by which thispea plant clings to a support aremodified leaves. After it has “lassoed”a support, a tendril forms a coil thatbrings the plant closer to the support.Tendrils are typically modified leaves,but some tendrils are modified stems,as in grapevines. Each plant organ hasdermal, vascular, andground tissues(b) Spines. The spines of cacti, suchas this prickly pear, are actuallyleaves, and photosynthesis iscarried out mainly by the fleshygreen stems. Tissue Organization of Leaves: The epidermal barrier in leaves is interruptedby stomata, which allow CO2 exchange between the surrounding air and thephotosynthetic cells within a leaf The ground tissue in a leaf is sandwiched between the upper and lowerepidermis The vascular tissue of each leaf is continuous with the vascular tissue of theGuardKeystemcellsto labelsDermalGroundVascular Leaf anatomyCuticleSclerenchymafibersStomatal poreEpidermalcell50 µm(b) Surface view of a spiderwort(Tradescantia) leaf (LM)StomaUpperepidermis(c) Storage leaves. Most succulents,such as this ice plant, have leavesmodified for storing water.(d) Bracts. Red parts of the poinsettiaare often mistaken for petals but areactually modified leaves called bractsthat surround a group of flowers.Such brightly colored leaves ardPhloem(a) Cutaway drawing of leaf tissues cells Like any multicellular organism a plant is characterized bycellular differentiation, the specialization of cells in structureand function Some of the major types of plant cells include: Parenchyma,Collenchyma, Sclerenchyma, Water-conducting cells of thexylem, sugar-conducting cells of the phloemCOLLENCHYMA CELLS80 µmCortical parenchyma cellsSCLERENCHYMA CELLS5 µmSclereid cellsin pear25 µm60 µmVeinAir spacesGuard cells(c) Transverse section of a lilac 100 µm(Syringa) leaf (LM) Vascular plants have two types of vascular tissue; thevascular tissue system carries out long-distance transport ofmaterials between roots and shoots; it consists of two tissues,xylem and phloem Xylem (includes dead cells called tracheids) conveys/conducts waterand dissolved minerals upward from roots into the shoots Phloem (consists of living cells) transports organic nutrients(sugars, amino acids, and other organic products) from wherethey are made to where they are needed Ground tissue includes various cells specialized forfunctions such as storage, photosynthesis, and supportCell wallParenchyma cellsLowerepidermisCuticleVein The dermal tissue system consists of the epidermis andperidermCommon Types of Plant CellsPARENCHYMA CELLSSpongymesophyllGuardcells(e) Reproductive leaves. The leavesof some succulents, such as Kalanchoedaigremontiana, produce adventitiousplantlets, which fall off the leaf andtake root in the BundlesheathcellCollenchyma cellsFiber cells5
Water-conducting cells of the xylem and sugarconducting cells of the phloemWATER-CONDUCTING CELLS OF THE XYLEMVessel TracheidsSUGAR-CONDUCTING CELLS OF THE PHLOEMSieve-tube members:longitudinal viewSieve-tubememberVessel elements withpartially perforatedend wallsNucleus30 µm15 µmTracheidsCompanioncellCytoplasm In woody plants primary and secondary growth occursimultaneously but in different locationsTerminal budBud scale Primary growthlengthens rootsand shoots Primary growthproduces theprimary plantbody, the parts ofthe root and shootsystems producedby apicalmeristemsPrimary ondary growth in stemsAn overviewof primaryandsecondarygrowthPithPrimaryxylemRoot e corkcambium addssecondarydermal tissue.CortexPrimaryphloemThe vascularcambium addsSecondarysecondaryphloemxylem andVascular cambiumphloem.Primary Growth of Roots The root tip is covered by a root cap, which protects thedelicate apical meristem as the root pushes through soilduring primary growthAxillary budsCortexVascular cylinderEpidermisLeaf scarNodeThis year’s growth(one year old)PithApical meristemsadd primary growth,or growth in ry phloemIn woody plants,there are lateralmeristems thatadd secondarygrowth, increasingthe girth ofroots and stems.Companion cellTracheids and vesselsPrimary growth in stemsShoot apicalmeristems(in buds)100 µmPits Meristems generate cells for new organs Apical meristems are located at the tips of roots and in thebuds of shoots; they elongate shoots and roots throughprimary growth Lateral meristems add thickness to woody plants throughsecondary growthKeyStemRoot hairDermalGroundInternodeOne-year-old sidebranch formedfrom axillary budnear shoot apexZone ofmaturationVascularZone ofelongationLeaf scarLast year’s growth(two years old)Scars left by terminalbud scales of previouswintersApicalmeristemZone of celldivisionRoot capLeaf scarGrowth of twoyears ago (threeyears old)100 µm The primary growth of roots produces the epidermis,ground tissue, and vascular tissue Organization of primary tissues in young rootsPrimary Growth of Shoots A shoot apical meristem is a dome-shaped mass ofdividing cells at the tip of the terminal bud; it gives rise to arepetition of internodes and leaf-bearing al meristemPericycleLeaf primordiaCore ofparenchymacellsXylem100 µmPhloem100 µm(a) Transverse section of a typical root. In theroots of typical gymnosperms and eudicots, aswell as some monocots, the stele is a vascularcylinder consisting of a lobed core of xylemwith phloem between the lobes.EndodermisPericycle(b) Transverse section of a root with parenchymain the center. The stele of many monocot rootsis a vascular cylinder with a core of parenchymasurrounded by a ring of alternating xylem and ularXylemPhloemAxillary budmeristems50 µm0.25 mm6
Primary and secondary growth of a stem Secondary growth adds girth to stems and roots in woodyplants Secondary growth occurs in stems and roots of woody plantsbut rarely in leavesCortex The secondary plant body consists of the tissues produced bythe vascular cambium and cork cambiumPrimaryxylemPith The vascular cambium is a cylinder of meristematic cells onecell thick; it develops from parenchyma cells1(a) Primary and secondary growthin a two-year-old mainly corkcambiaand cork)PithSecondaryxylemLate woodEarly woodSecondary phloemVascular cambiumCorkcambiumPeridermCorkPrimary phloemCortexEpidermis2Phloem rayth3GrowXylemrayXylem rayBarkVascularcambium0.5 mm Viewed in transversesection, the vascularcambium appears asa ring, withinterspersed regionsof dividing cells calledfusiform initials andray initialsCCXCCP(a) Types of cell division. An initial can dividetransversely to form two cambial initials (C)or radially to form an initial and either axylem (X) or phloem (P) cell.XCXCXCPAs primary growth continues to elongate the stem, the portionof the stem formed earlier the same year has already startedits secondary growth. This portion increases in girth as fusiforminitials of the vascular cambium form secondary xylem to theinside and secondary phloem to the outside.PrimaryxylemSecondary xylemVascular cambiumSecondary phloemPrimary phloem4 First cork cambiumCorkthGrowMost recentcork cambiumThe ray initials of the vascular cambium give rise to the xylemand phloem rays.As the diameter of the vascular cambium increases, thesecondary phloem and other tissues external to the cambiumcannot keep pace with the expansion because the cells nolonger divide. As a result, these tissues, including theepidermis, rupture. A second lateral meristem, the corkcambium, develops from parenchyma cells in the cortex. Thecork cambium produces cork cells, which replace the epidermis.5In year 2 of secondary growth, the vascular cambium adds tothe secondary xylem and phloem, and the cork cambiumproduces cork.6As the diameter of the stem continues to increase, theoutermost tissues exterior to the cork cambium rupture andslough off from the stem.67 Cork cambium re-forms in progressively deeper layers of thecortex. When none of the original cortex is left, the corkcambium develops from parenchyma cells in thesecondary phloem.Secondaryxylem (twoyears ofproduction)Vascular cambiumSecondary phloem53489 Bark7 CorkEach cork cambium and the tissues it produces form alayer of periderm.9 Bark consists of all tissues exterior to the vascularcambium.8 Layers ofperiderm As a tree or woody shrub ages, the older layers of secondaryxylem, the heartwood, no longer transport water and minerals The outer layers, known as sapwood still transport materialsthrough the xylemGrowth ring(b) Transverse sectionof a three-yearold stem (LM)0.5 mmIn the youngest part of the stem, you can see the primaryplant body, as formed by the apical meristem during primarygrowth. The vascular cambium is beginning to develop.PithPrimary xylemVascular SecondaryxylemPrimary xylem12XCPXXCPP(b) Accumulation of secondary growth. Although shown hereas alternately adding xylem and phloem, a cambial initial usuallyproduces much more xylem.Cork Cambia and theProduction of Periderm- The cork cambiumVascularraygives rise to thesecondary plantbody’s protectiveHeartwoodcovering, or periderm- Periderm consists of SecondaryxylemSapwoodthe cork cambium plusthe layers of cork cellsVascular cambiumit producesSecondary phloem- Bark consists of allthe tissues external to BarkLayers of peridermthe vascular cambium,including secondaryphloem and periderm Arabidopsis is the first plant to have its entire genomesequencedCell organization and biogenesis (1.7%)Unknown(36.6%)DNA metabolism (1.8%)Carbohydrate metabolism (2.4%)Signal transduction (2.6%)Protein biosynthesis (2.7%)Electron transport(3%)Molecular Biology: Revolutionizing the Study of PlantsProteinmodification (3.7%)Proteinmetabolism (5.7%) New techniques and model systems are catalyzingexplosive progress in our understanding of plantsTranscription (6.1%)Other metabolism (6.6%)Other biologicalprocesses (18.6%)Transport (8.5%)Growth: Cell Division and Cell Expansion By increasing cell number cell division in meristemsincreases the potential for growth Cell expansion accounts for the actual increase in plant size7
Microtubules and Plant Growth Studies of fass mutants of Arabidopsis have confirmed theimportance of cytoplasmic microtubules in cell division andexpansion Morphogenesis in plants, as in other multicellularorganisms, is often under the control of homeoticgenesMorphogenesis and PatternFormation Pattern formation is thedevelopment of specific structuresin specific locations; it isdetermined by positionalinformation in the form of signalsthat indicate to each cell its location(b) fass seedling(a) Wild-type seedling (c) Mature fass mutantGene Expression and Control of Cellular DifferentiationLocation and a Cell’s Developmental Fate In cellular differentiation cells of a developing organismsynthesize different proteins and diverge in structure andfunction even though they have a common genome Cellular differentiation to a large extent depends onpositional information; is affected by homeotic genes A cell’s position in a developing organ determines itspathway of differentiationWhen epidermal cells border a single corticalcell, the homeotic gene GLABRA-2 is selectivelyexpressed, and these cells will remain hairless.(The blue color in this light micrograph indicates cells in which GLABRA-2 is expressed.)Shifts in Development: Phase Changes Plants pass throughdevelopmental phases, calledphase changes, developing froma juvenile phase to an adultvegetative phase to an adultreproductive phaseHere an epidermal cell borders twocortical cells. GLABRA-2 is not expressed,and the cell will develop a root hair.Corticalcells The most obvious morphologicalchanges typically occur in leafsize and shape20 µmThe ring of cells external to the epidermal layer is composed of rootcap cells that will be sloughed off asthe root hairs start to differentiate.Genetic Control of Flowering Flower formation involves aphase change from vegetativegrowth to reproductive growth;it is triggered by acombination of environmentalcues and internal signalsCaSt The transition from vegetativegrowth to flowering isPeassociated with the switchingSeon of floral meristem identity(a) Normal Arabidopsis flower. Arabidopsisgenesnormally has four whorls of flower parts: sepals(Se), petals (Pe), stamens (St), and carpels (Ca). Plant biologists have identifiedAbnormal Arabidopsis flower. Reseachers haveseveral organ identity genes (b) identifiedseveral mutations of organ identitythat cause abnormal flowers to develop.that regulate the development genesThis flower has an extra set of petals in place ofstamens and an internal flower where normalplants have carpels.of floral patternLeaves producedby adult phaseof apical meristemLeaves producedby juvenile phaseof apical meristemLignin biotechnology: Antisense (gene ko) CAD and COMT genes in poplarsKraft pulping of tree trunks showed that the reduced-CAD lines had improvedcharacteristics, allowing easier de-lignification, using smaller amounts of chemicals,while yielding more high-quality pulp. This work highlights the potential ofengineering wood quality for more environmentally benign papermaking withoutinterfering with tree growth or fitness.Nature Biotechnology 20, 607 - 612 (2002)PeSePePeRed color shows differenttype of lignin has beenproduced.SeMore infos about this application and problem also in CHM4006 Biochem. course8
Lignin and biofuel production Lignin has negative impacts on biofuel prodution–lignin impedes access of hydrolytic enzymes to wallpolysaccharides–lignin adsorbs hydrolytic enzymes–lignin interferes with pretreatment processes–lignin degradation products inhibit fermentation–lignin is not fermentable (but its energy can be utilized) Lignin, part of the plant cell wall, is essential for plant viability; allthe genes are known. Lignin (20%) provides stiffness, rigidity andprevents water absorption so that water can be transported; andprotects against insects and fungi. Can reducing lignin content, composition, and tissue specificityimprove biomass quality? Plants seem to tolerate substantiallignin modification.CelluloseBiomass to Bioenergy³ Biomass: renewable energy sources comingfrom biological material such as plants, animals,microorganisms and municipal wastesCellulose is an organic compoundwith the formula (C6H10O5)n, apolysaccharide consisting of a linearchain of several hundred to manythousands of β(1 4) linked Dglucose units. Cellulose is animportant structural component of theprimary cell wall of green plants,many forms of algae and theoomycetes. Some species of bacteriasecrete it to form biofilms.The crystalline regions of cellulose have intramolecular andintermolecular hydrogen bonds, allowing the linear glucanchains to form crystalline structures that exclude water andenzymes.Intramolecular:The H of the OH on C3 to theO that makes the glycosidicbonds.Intermolecular:The H of the OH on C6 to theO of the OH on C3. These arethe bonds that make the verytight structure of cellulosemicrofibrils. Microfibrils have30-40 chains each with 2000to 10,000 glucose units.Lignin modification may decrease theneed for pretreatmentLignin biosynthetic pathway in woody angiosperms (e.g. aspen or poplar)9
--- PhenylalanineLignin biosynthetic pathway in woodyangiosperms (the flowering plants)(e.g. aspen or poplar)Secretion is followed by oxidativepolymerization catalyzed by peroxidase10
(nonvascular plants) Seedless vascular plants Seed plants Vascular plants Land plants . The general groups of seedless vascular plants . 2 Phylum Lycophyta: Club Mosses, Spike Mosses, and Quillworts . No two Pla
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Vietnamese-German Programme "Reform of TVET in Vietnam", compiled this "Greening TVET" brochure. The brochure is developed from the results of technical workshops on the 'Action Plan for Greening TVET', and on 'Greening of TVET institutes' organized in July 2018, as well as various Vietnamese and
Le genou de Lucy. Odile Jacob. 1999. Coppens Y. Pré-textes. L’homme préhistorique en morceaux. Eds Odile Jacob. 2011. Costentin J., Delaveau P. Café, thé, chocolat, les bons effets sur le cerveau et pour le corps. Editions Odile Jacob. 2010. Crawford M., Marsh D. The driving force : food in human evolution and the future.
