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Plant-Microbe Interactions

Plant-Microbe Interactions. SUMBER: culter.colorado.edu/~ kittel /Slides18_13Nv07. ppt ‎. INTERAKSI TANAMAN-MIKROBA. Plant-microbe interactions diverse – from the plant perspective: Negatif – e.g. Parasitis / Pathogenik Neutral Positif – Simbiotik.

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Plant-Microbe Interactions

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  1. Plant-Microbe Interactions SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  2. INTERAKSI TANAMAN-MIKROBA • Plant-microbe interactions diverse – from the plant perspective: • Negatif– e.g. Parasitis/ Pathogenik • Neutral • Positif– Simbiotik • Pokokbahasan important positive interactions with respect to plant abundance and distribution – related to plant nutrient and water supply: • Dekomposisi BOT • Mycorrhizae • Fiksasi N2 • Rhizosphere Perananinteraksiinidalamsiklus N SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  3. I. DekomposiBahanOrganik • Input rates – • Generally follow rates of production • Deciduous = evergreen • Pemasokutamaharatanaman – terutama N & P • Bahanmentah • Soil organic matter derived primarily from plants – • Mainly leaves and fine roots • Wood can be important component in old growth forests SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  4. B. Proses-Proses nematode termites springtail (Isotoma viridis) • 1. FragmentasiBahanOrganik • Breakdown of organic matter (OM) into smaller bits = humus • By soil ‘critters’ – including nematodes, earthworms, springtails, termites • consume and excrete OM  incomplete digestion SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  5. 2. MineralisasiBahanOrganik • Breakdown OM senyawa an-organik • Microbial process: accomplished by enzymes excreted into the soil For Nitrogen energy for heterotrophic bacteria Mineralization Ammonium NH4+ proteins (insoluble) amino acids proteases Immobilization Nitrification Nitrite NO2- energy for nitrifying bacteria* Microbial uptake Nitrate NO3- Plant uptake • * In 2 steps by 2 different kinds of bacteria – (1) Nitrosomonas oxidize NH3 to nitrites + (2) Nitrobacter oxidize nitrites to nitrates SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  6. C. Serapan N olehTanaman– Chemical form taken up can vary mineralization Protein NH4+ NO3- SerapanTanaman • 1) Nitrate (NO3-) • Lebihdisenangiolehtanaman, lebihmudahdiserap • Even though requires conversion to NH4+before be used  lots of energy • vs. taking up & storing NH4+ problematic • More strongly bound to soil particles • Acidifies the soil • Not easily stored • 2) Ammonium (NH4+ ) – • Digunakanlangsungolehtanamandalamtanah yang nitrifikasinyalambat (mis. Tanah basah) SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  7. 3) Beberapajenistanamanmenyerapsedikitasam amino (mis. glycine) • Circumvents the need for N mineralization • Difasilitasiolehadanyamycorrhiza proteins mineralization NH4+ amino acids immobilization nitrification microbial uptake NO3- Penyerapanlangsung SerapanTanaman SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  8. D. KontrolthdKecepatanDekomposisi BO • Temperature – • Warmer is better • <45°C • 2) Moisture – intermediate is best • Too little  desiccation • Too much  limits O2 diffusion RespirasiMikroba Tanah T Soil Moisture % SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  9. 3) FaktorTanaman – Kualitasbiomasaseresah Decomposition rate as fn(lignin, N) Deciduous forest spp • b) Material strukturaltanaman • Lignin – complex polymer, cell walls • Confers strength with flexibility • – e.g. oak leaves • Relatively recalcitrant • High conc.  lowers decomposition • a) Rasio C:N biomasaseresah( = Konsentrasi N) • If C relative to N high  N limits microbial growth • Immobilization favored • N to plants  SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  10. OH R c) Senyawasekundertanaman • Anti-herbivore/microbial • Common are phenolics – e.g. tannins • – Aromatic ring + hydroxyl group, other compounds • KontroldekomposisiBahanorganikoleh: • Bind to enzymes, blocking active sites lower mineralization • N compounds bind to phenolicsgreater immobilization by soil • Phenolics C source for microbes greater immobilization by microbes SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  11. II. Mycorrhiza = JamurAkar • HubunganSimbiotikantaratanaman (akar) & fungi tanah • Plant provides fungus with energy (C) • Fungus enhances soil resource uptake • Penyebarannya: • Occurs ~80% angiosperm spp • All gymnosperms • Sometimes an obligaterelationship. SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  12. KelompokutamaMycorrhiza: • 1) Ectomycorrhiza– • Fungus forms “sheath” around the root (mantle) • Grows in between cortical cells = Hartig net – apoplastic connection • Occur most often • in woody spp SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  13. 2) Endomycorrhiza– • Fungi menembussel-selakar Arbuscule in plant cell • Common example is arbuscularmycorrhizae (AM) • Found in both herbaceous & woody plants • Arbuscule = exchange site SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  14. C. FungsiMycorrhiza: • Perananpenghubungtanaman-tanah: • Increase surface area & reach for absorption of soil water & nutrients • Increase mobility and uptake of soil P • Provides plant with access to organic N • Protect roots from toxic heavy metals • Protect roots from pathogens • Efekharatanahthdmycorrhiza • Intermediate soil P concentrations favorable • Extremely low P – poor fungal infection • Hi P – plants suppress fungal growth • – taking up P directly • Kejenuhan N SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  15. III. Fikisasi N2 • N2 abundant – chemically inert • N2 must be fixed = converted into chemically usable form • Lightning • High temperature or pressure (humans) • Biologically fixed • Nitrogenase– EnsimKatalisisN2 NH3 • Expensive process – ATP, Molybdenum • Anaerobik : Memerlukanstrukturkhusus SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  16. A. Hanyaterjadipadaorganisme Prokaryote: • Bacteria (e.g. Rhizobium, Frankia) • Cyanobacteria (e.g. Nostoc, Anabaena) • Free-living in soil/water – heterocysts • Symbiotic with plants – root nodules • Loose association with plants Anabaena with heterocysts • Simbiosisdengantumbuhan– Mutualism • Prokaryote receives carbohydrates • Plant may allocate up to 30% of its C to the symbiont • Tumbuhanmenyediakantapakanaerobik – Bintilakar • Tumbuhanmenerima N SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  17. soybean root • Contohsistemsimbiotikfiksasi N2olehtumbuhan • Legumes (Fabaceae) • Widespread • bacteria = e.g., Rhizobiumspp. • Those with N2-fixing symbionts form root “nodules” • – anaerobic sites that “house” bacteria SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  18. Problem Toksisitas O2 • Symbionts regulate O2 in the nodule with leghemoglobin • Different part synthesized by the bacteria and legume Cross-section of nodules of soybean nodules • Symbiontsmengendalikan O2dalambintilakardenganmembentukleghemoglobin • An oxygen carrier (in legumes) to prevent oxygen toxicity for the bacterium • different pieces synthesized by the bacteria (heme) and in the plant (protein) SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  19. 2) Simbiosistumbuhan Non-legume: • “Actinorhizal”= associated with actinomycetes (N2-fixing bacteria) • genus Frankia • Usually woody species – e.g. Alders, Ceanothus Ceanothus velutinus - snowbrush Ceanothus roots, with Frankia vesicles Bacteria in root or small vesicles SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  20. (2) Simbiosistumbuhan Non-legume “Actinorhizal”= associated with actinomycetes (N2-fixing bacteria) genus Frankia Usually woody species – e.g. Alders, Ceanothus Bacteria occur in root or small vesicles Buffaloberry (Shepherdiaargentea) - actinorhizal shrub (Arizona) • Bacteria in root or small vesicles SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  21. B. MaknaEkologisFiksasi N2 • (1). Important in “young” ecosystems – • Young soils low in organic matter, N • Ecological importance of N2 fixation • (1) Most important in “young” ecosystems (early in primary succession) - • young soils are low in organic matter, and thus N, which is often a limiting nutrient for plant growth • e.g., newly exposed (glaciated) or newly laid down rock (volcanic), • recently denuded landscapes(human activities, directly or indirectly – bulldozing, erosion SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  22. 2) Plant-level responses to increased soil N conc: • Some plants (facultative N-fixers) respond to soil N concentration  • Plant shifts to direct N uptake • N fixation  • Number of nodules decreases • Plant-level: responses on N-fixing plants to high soil N conc: • In some plants (facultative N-fixers) – • As N conc, N fixation decreases • Plant shifts to direct N uptake • #nodules decreases SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  23. 3) Kompetisi: Interaksitumbuhanfiksasi N • N2-fixing plants higher P, light, Mo, and Fe requirements •  Poor competitors • Competitive exclusion less earlier in succession • Though - N2 fixers in “mature” ecosystems • Competition – N-fixers and plant community interactions • because N2 fixing plants have higher P, light, Mo, and Fe requirements . • They are believed to be poor competitors; • chances for competitive exclusion lower earlier in succession (although there are N2 fixers in “mature” ecosystems) • e.g. of plants important in early stages of succession: • lupines, alders, clovers, Dryas SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  24. PLANT REMAINS PLANT Natural N cycle • IV. Kehilangan N dariekosistem • Leaching  to aquatic systems • Kebakaran Penguapan • Denitrifikasi N2, N2O to atmosfir • – Closes the N cycle! • Bacteria mediated • Anaerobik. N2O SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  25. Fertilizer 80 Legumes, other plants 40 Fossil fuels 20 Biomass burning 40 Wetland draining 10 Land clearing 20 Total from human sources 210 Annual release(1012 g N/yr) NATURAL SOURCES Soil bacteria, algae, lightning, etc. 140 ANTHROPOGENICSOURCES Annual release(1012 g N/yr) Altered N cycle Annual release of fixed N2 (1012 g = teragram, trillion gr) Source: Peter M. Vitouseket al., "Human Alteration of the Global Nitrogen Cycle: Causes and Consequences," Issues in Ecology, No. 1 (1997), pp. 4-6. From - Peter M. Vitouseket al., "Human Alteration of the Global Nitrogen Cycle - Causes and Consequences," Issues in Ecology, No. 1 (1997), pp. 4-6.

  26. V. InteraksiRhizosphere • Jaring-jaringmakananbawahtanah Fine root • Zone within 2 mm of roots – hotspot of biological activity • Roots exude C & cells slough off = lots of goodies for soil microbes  lots of microbes for their consumers (protozoans, arthropods) • “Free living” N2-fixers thrive in the rhizosphere of some grass species SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

  27. RINGKASAN • Plant–microbial interactions play key roles in plant nutrient dynamics • Decomposition – • mineralization, nitrification … • immobilization, denitrification … • Rhizosphere – soil foodweb • Mycorrhizae – plant-fungi symbiosis • N fixation – plant-bacteria symbiosis • Highly adapted root morphology and physiology to accommodate these interactions • N cycle, for example, significantly altered by human activities SUMBER: culter.colorado.edu/~kittel/Slides18_13Nv07.ppt‎

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