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TINJAUAN KRITISTINJAUAN KRITIS
Judul “Microsymbiont” tanah dalam Judul “Microsymbiont” tanah dalam Sistem AgroforestrySistem Agroforestry
Jenis-jenis organisme Bakteri Nitrogen-Jenis-jenis organisme Bakteri Nitrogen-Fixation yang lain?Fixation yang lain?
Perkiraan konstribusi Nitrogen ke dalam Perkiraan konstribusi Nitrogen ke dalam tanah?tanah?
Jenis-jenis Mycorrhiza?Jenis-jenis Mycorrhiza?
MIKROORGANISME TANAH
DALAM SISTEM AGROFORESTRY
SymbiosisSymbiosis = close and intimate = close and intimate association of two species; a “living association of two species; a “living together”together”
Terms:Terms: MacrosymbiontMacrosymbiont – higher plant – higher plant MicrosymbiontMicrosymbiont – microorganism – microorganism
Some Nitrogen Fixing Organisms
• Free living aerobic bacteria– Azotobacter– Beijerinckia– Klebsiella– Cyanobacteria (lichens)
• Free living anaerobic bacteria– Clostridium– Desulfovibrio– Purple sulphur bacteria– Purple non-sulphur bacteria– Green sulphur bacteria
• Free living associative bacteria– Azospirillum
• Symbionts– Rhizobium (legumes)– Frankia (alden trees)
Estimated Average Rates of Biological NEstimated Average Rates of Biological N22
FixationFixationOrganism or systemOrganism or system NN22 fixed (kg ha fixed (kg ha-1-1 y y-1-1))
Free-living microorganismsFree-living microorganismsCyanobacteria Cyanobacteria Azotobacter Azotobacter Clostridium pasteurianumClostridium pasteurianum
25250.30.3
0.1-0.50.1-0.5
Grass-Bacteria associative symbiosesGrass-Bacteria associative symbiosesAzospirillumAzospirillum 5-255-25
Cyanobacterial associationsCyanobacterial associationsGunnera Gunnera AzollaAzollaLichensLichens
10-2010-20300300
40-8040-80
Leguminous plant symbioses with rhizobiaLeguminous plant symbioses with rhizobia
Grain legumes (Grain legumes (Glycine,Glycine, Vigna, Lespedeza, PhaseolusVigna, Lespedeza, Phaseolus))
Pasture legumes (Pasture legumes (Trifolium, Medicago, LupinusTrifolium, Medicago, Lupinus))
50-10050-100
100-600100-600
Actinorhizal plant symbioses with Actinorhizal plant symbioses with FrankiaFrankia
AlnusAlnus
HippophaëHippophaë
CeanothusCeanothus
CoriariaCoriaria
CasuarinaCasuarina
40-30040-300
1-1501-150
1-501-50
50-15050-150
5050
Rank of Biological Nitrogen Fixation
NN22 fixing system fixing system Nitrogen Fixation Nitrogen Fixation (kg N/ha/year)(kg N/ha/year)
Rhizobium-Rhizobium-legumelegume
50 - 60050 - 600
Cyanobacteria- Cyanobacteria- mossmoss
10 - 30010 - 300
Rhizosphere Rhizosphere associationsassociations
5 - 255 - 25
Free- livingFree- living 0.1 - 250.1 - 25
Types of Biological Nitrogen FixationTypes of Biological Nitrogen Fixation
Free-living (asymbiotic)Free-living (asymbiotic) CyanobacteriaCyanobacteria AzotobacterAzotobacter
AssociativeAssociative RhizosphereRhizosphere––AzospirillumAzospirillum LichensLichens–cyanobacteria–cyanobacteria Leaf nodulesLeaf nodules
SymbioticSymbiotic Legume-rhizobiaLegume-rhizobia Actinorhizal-Actinorhizal-FrankiaFrankia
Biological Nitrogen Fixation: The Symbiosis
N2
N2
N2
NH3
N2 represents the largest pool of biologically active nitrogen in terrestrial ecosystems reaching 27,000 g N per m3.
Taxonomy of RhizobiaTaxonomy of Rhizobia
GenusGenus SpeciesSpecies Host plantHost plantRhizobiumRhizobium leguminosarum bv. trifoliileguminosarum bv. trifolii
“ “ bv. viciaebv. viciae “ “ bv. phaseolibv. phaseolitropicitropicietlietli
TrifoliumTrifolium (clovers) (clovers)PisumPisum (peas), (peas), ViciaVicia (field beans), (field beans), LensLens (lentils), (lentils), LathyrusLathyrusPhaseolusPhaseolus (bean) (bean)PhaseolusPhaseolus (bean), (bean), LeucaenaLeucaenaPhaseolusPhaseolus (bean) (bean)
SinorhizobiumSinorhizobium melilotimelilotifrediifrediisahelisaheliterangateranga
MelilotusMelilotus (sweetclover), (sweetclover), MedicagoMedicago (alfalfa), (alfalfa), TrigonellaTrigonellaGlycineGlycine (soybean) (soybean)SesbaniaSesbania Sesbania, AcaciaSesbania, Acacia
BradyrhizobiumBradyrhizobium japonicumjaponicumelkaniielkaniiliaoningenseliaoningense
GlycineGlycine (soybean) (soybean)GlycineGlycine (soybean) (soybean)GlycineGlycine (soybean) (soybean)
AzorhizobiumAzorhizobium caulinodanscaulinodans SesbaniaSesbania (stem nodule) (stem nodule)
‘‘Meso rhizobium’Meso rhizobium’ lotilotihuakuiihuakuiicicericiceritianshanensetianshanensemediterraneummediterraneum
LotusLotus (trefoil) (trefoil)AstragalusAstragalus (milkvetch) (milkvetch)CicerCicer (chickpea) (chickpea)
CicerCicer (chickpea) (chickpea)
[Rhizobium][Rhizobium] galegaegalegae GalegaGalega (goat’s rue), (goat’s rue), LeucaenaLeucaena
PhotorhizobiumPhotorhizobium spp.spp. AeschynomeneAeschynomene (stem nodule) (stem nodule)
RHIZOBIUMRHIZOBIUM
A few legumes (such as Sesbania rostrata) have stem nodules as well as root nodules. Stem nodules (arrows) are capable of photosynthesis as well as nitrogen fixation.
Symbiotic Rhizobia are classified in two groups:
Fast-growing Rhizobium spp. whose nodulation functions(nif, fix) are encoded on their symbiotic megaplasmids
(pSym)
Slow-growing Bradyrhizobium spp. whose N-fixation and nodulation functions are encoded on their chromosome.
There are also two types of nodule that can be formed:
determinate and
indeterminateThis outcome is controlled by the plant host
Formed on tropical legumes by Rhizobium and Bradyrhizobium
Meristematic activity not persistent - present only during early stage of nodule formation; after that, cells simply expand rather than divide, to form globose nodules.
Determinate nodules
www.agsci.ubc.ca/courses/agro/426/AGRO426.kronstad.rhizobium.01.ppt
Indeterminate nodules
Formed on temperate legumes (pea, clover, alfalfa);typically by Rhizobium spp.
Cylindrical nodules with a persistent meristem;nodule growth creates zones of different developmentalstages
www.agsci.ubc.ca/courses/agro/426/AGRO426.kronstad.rhizobium.01.ppt
Rhizobium Root Nodules
Nodulation in LegumesNodulation in Legumes
Nodule Formation Nodule Formation
Once inside the coritcal cell, the bacteria Once inside the coritcal cell, the bacteria multiple and dedifferentiatemultiple and dedifferentiate
Infected root cells swell and stop dividingInfected root cells swell and stop dividing After dedifferentiation, the Rhizobium are After dedifferentiation, the Rhizobium are
referred to as a bacteroid referred to as a bacteroid After formation, the bacteroid begin to After formation, the bacteroid begin to
express nif and fix genes and the plant express nif and fix genes and the plant expresses late nodulin genes expresses late nodulin genes
F R A N K I AF R A N K I A
Actinorhizal Plant Hosts Actinorhizal Plant Hosts (Non-Legum)(Non-Legum)
FamilyFamily GeneraGenera
BetulaceaeBetulaceae AlnusAlnus
CasuarinaceaeCasuarinaceae Allocasuarina, Casuarina, Ceuthostoma, GymnostomaAllocasuarina, Casuarina, Ceuthostoma, Gymnostoma
MyricaceaeMyricaceae Comptonia, MyricaComptonia, Myrica
ElaeagnaceaeElaeagnaceae Elaeagnus, HippophaElaeagnus, Hippophaë, Shepherdiaë, Shepherdia
RhamnaceaeRhamnaceae Ceanothus, Colletia, Discaria, Kentrothamnus, Retanilla, Ceanothus, Colletia, Discaria, Kentrothamnus, Retanilla, Talguenea, TrevoaTalguenea, Trevoa
RosaceaeRosaceae Cercocarpus, Chamaebatia, Cowania, Dryas, PurshiaCercocarpus, Chamaebatia, Cowania, Dryas, Purshia
CoriariaceaeCoriariaceae CoriariaCoriaria
DatiscaceaeDatiscaceae DatiscaDatisca
FrankiaFrankia and Actinorhizal Plants and Actinorhizal Plants
Actinomycetes (Gram +, filamentous); septate Actinomycetes (Gram +, filamentous); septate hyphae; spores in sporangia; thick-walled hyphae; spores in sporangia; thick-walled vesiclesvesicles
Frankia vesicles showing thick walls that confer protection from oxygen. Bars are 100 nm.
Beberapa Tipe Mycorrhizae Yang Beberapa Tipe Mycorrhizae Yang Telah Dikenal Telah Dikenal
VAM (Vescicular Arbuscular VAM (Vescicular Arbuscular Mycorrhyzae)Mycorrhyzae)
ECM (Ectomycorrhyzae)ECM (Ectomycorrhyzae) EctendomycorrhyzaeEctendomycorrhyzae Ericoid mycorrhyzaeEricoid mycorrhyzae Orchid mycorrhyzaeOrchid mycorrhyzae
Endo- and EctomycorrhizaEndo- and Ectomycorrhiza
Wide-spread association:Wide-spread association: Gymnosperms: 100% infectedGymnosperms: 100% infected Dicots: 83% infectedDicots: 83% infected Monocots: 79% infectedMonocots: 79% infected
Three parts to mycorrhizal associations:Three parts to mycorrhizal associations: RootRoot Fungal structures in close association with the Fungal structures in close association with the
rootroot External myceliumExternal mycelium
Endo- and EctomycorrhizaEndo- and Ectomycorrhiza
EctomycorrhizasEctomycorrhizas Fungal tissue largely outside the rootFungal tissue largely outside the root Primarily found in woody species, but also Primarily found in woody species, but also
some ferns and monocotssome ferns and monocots EndomycorrhizasEndomycorrhizas
Large fraction of the fungal tissue is within the Large fraction of the fungal tissue is within the root cortical cellsroot cortical cells
Frequently occur on herbaceous plants, also Frequently occur on herbaceous plants, also some tropical treessome tropical trees
Endo- and EctomycorrhizaEndo- and Ectomycorrhiza
Vesicular arbuscular mycorrhiza (VAM)Vesicular arbuscular mycorrhiza (VAM) Type of endomycorrhiza with specialized Type of endomycorrhiza with specialized
structures (vesicles and arbuscules)structures (vesicles and arbuscules) Fungi belong to Glomales (Fungi belong to Glomales (GlomusGlomus largest largest
genus)genus) Considered the most ancient type of Considered the most ancient type of
mycorrhizal symbiosismycorrhizal symbiosis Roots of more than 80% of all plant species Roots of more than 80% of all plant species
are infected with VAM-forming fungiare infected with VAM-forming fungi
Endo- and EctomycorrhizaEndo- and Ectomycorrhiza
VAM infection processVAM infection process Spores are found in the soil, or fungi may Spores are found in the soil, or fungi may
colonize from other plant rootscolonize from other plant roots Forms an Forms an appressoriumappressorium only on host plants, only on host plants,
colonizes through colonizes through passage cellspassage cells of exodermis of exodermis Hyphae remain in cortex and don’t penetrate Hyphae remain in cortex and don’t penetrate
through endodermis to stelethrough endodermis to stele Ecomycorrhiza infection processEcomycorrhiza infection process
Form a mantle of fungal hyphaeForm a mantle of fungal hyphae Hyphae penetrate intercellular into the cortex, Hyphae penetrate intercellular into the cortex,
forming forming Hartig netHartig net
Perbedaan Antara ECM dan VAM Perbedaan Antara ECM dan VAM Secara Garis BesarSecara Garis Besar
ECM ECM (Ectomycorrizae)(Ectomycorrizae)
VAM (Vescicular VAM (Vescicular Arbuscular Mycorrhizae)Arbuscular Mycorrhizae)
Umumnya BasidiomycetesUmumnya Basidiomycetes Umumnya EndogonalesUmumnya Endogonales
Terdapat pada jenis pohon Terdapat pada jenis pohon membentuk Hartig net membentuk Hartig net antara sel-sel cortexantara sel-sel cortex
Terdapt pada tumbuhan Terdapt pada tumbuhan kecil Hyphae masuk kecil Hyphae masuk langsung ke dalam sel-sel langsung ke dalam sel-sel cortexcortex
Membentuk mantel yang Membentuk mantel yang menyelimuti akarmenyelimuti akar
Tidak membentuk mantelTidak membentuk mantel
Puluhan ribu jenis cendawanPuluhan ribu jenis cendawan Hanya puluhan jenisHanya puluhan jenis
Hyphae bisa jauh dari akarHyphae bisa jauh dari akar Hyphae tumbuh dekat akarHyphae tumbuh dekat akar
Figure. Schematic structure of a vesicular-arbuscular Figure. Schematic structure of a vesicular-arbuscular mycorrhiza (VAM). mycorrhiza (VAM).
ENDOMYCCORHIZA
ECTOMYCORRHIZA
http://www.irwantoshut.co.cc/
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