1. TINJAUAN KRITIS  Judul “Microsymbiont” tanah dalam Sistem Agroforestry  Jenis-jenis organisme Bakteri Nitrogen- Fixation yang lain?  Perkiraan konstribusi Nitrogen ke dalam tanah?  Jenis-jenis Mycorrhiza? MIKROORGANISME TANAH DALAM SISTEM AGROFORESTRY

2. SSSSymbiosis = close and intimate association of two species; a “living together” TTTTerms: Macrosymbiont – higher plant Microsymbiont – microorganism

3. 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)

4. Estimated Average Rates of Biological N 2 Fixation Organism or system N 2 fixed (kg ha -1 y -1 ) Free-living microorganisms CyanobacteriaAzotobacter Clostridium pasteurianum 250.30.1-0.5 Grass-Bacteria associative symbioses Azospirillum5-25 Cyanobacterial associations GunneraAzollaLichens10-2030040-80 Leguminous plant symbioses with rhizobia Grain legumes (Glycine, Vigna, Lespedeza, Phaseolus) Pasture legumes (Trifolium, Medicago, Lupinus) 50-100100-600 Actinorhizal plant symbioses with Frankia AlnusHippophaëCeanothusCoriariaCasuarina40-3001-1501-5050-15050

5. Rank of Biological Nitrogen Fixation N 2 fixing system Nitrogen Fixation (kg N/ha/year) Rhizobium-legume 50 - 600 Cyanobacteria- moss 10 - 300 Rhizosphere associations 5 - 25 Free- living 0.1 - 25

6. Types of Biological Nitrogen Fixation Free-living (asymbiotic)  Cyanobacteria  Azotobacter Associative  Rhizosphere–Azospirillum  Lichens–cyanobacteria  Leaf nodules Symbiotic  Legume-rhizobia  Actinorhizal-Frankia

7. Biological Nitrogen Fixation: The Symbiosis N2N2 N2N2 N2N2 NH 3 N 2 represents the largest pool of biologically active nitrogen in terrestrial ecosystems reaching 27,000 g N per m 3.

9. Taxonomy of Rhizobia GenusSpecies Host plant Rhizobium leguminosarum bv. trifolii “ bv. viciae “ bv. viciae “ bv. phaseoli “ bv. phaseolitropicietli Trifolium (clovers) Pisum (peas), Vicia (field beans), Lens (lentils), Lathyrus Phaseolus (bean) Phaseolus (bean), Leucaena Phaseolus (bean) Sinorhizobiummelilotifrediisaheliteranga Melilotus (sweetclover), Medicago (alfalfa), Trigonella Glycine (soybean) Sesbania Sesbania, Acacia Bradyrhizobiumjaponicumelkaniiliaoningense Glycine (soybean) Azorhizobiumcaulinodans Sesbania (stem nodule) ‘Meso rhizobium’ lotihuakuiiciceritianshanensemediterraneum Lotus (trefoil) Astragalus (milkvetch) Cicer (chickpea) [Rhizobium]galegae Galega (goat’s rue), Leucaena Photorhizobiumspp. Aeschynomene (stem nodule)

10. RHIZOBIUM

11. 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.

12. 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 indeterminate This outcome is controlled by the plant host

13. 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

14. 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 developmental stages www.agsci.ubc.ca/courses/agro/426/AGRO426.kronsta d.rhizobium.01.ppt

15. Rhizobium Root Nodules

16. Nodulation in Legumes

17. Nodule Formation  Once inside the coritcal cell, the bacteria multiple and dedifferentiate  Infected root cells swell and stop dividing  After dedifferentiation, the Rhizobium are referred to as a bacteroid  After formation, the bacteroid begin to express nif and fix genes and the plant expresses late nodulin genes

19. F R A N K I A

20. Actinorhizal Plant Hosts (Non-Legum) FamilyGenera BetulaceaeAlnus Casuarinaceae Allocasuarina, Casuarina, Ceuthostoma, Gymnostoma Myricaceae Comptonia, Myrica Elaeagnaceae Elaeagnus, Hippophaë, Shepherdia Rhamnaceae Ceanothus, Colletia, Discaria, Kentrothamnus, Retanilla, Talguenea, Trevoa Rosaceae Cercocarpus, Chamaebatia, Cowania, Dryas, Purshia CoriariaceaeCoriaria DatiscaceaeDatisca

21. Frankia and Actinorhizal Plants  Actinomycetes (Gram +, filamentous); septate hyphae; spores in sporangia; thick-walled vesicles Frankia vesicles showing thick walls that confer protection from oxygen. Bars are 100 nm.

23. Beberapa Tipe Mycorrhizae Yang Telah Dikenal  VAM (Vescicular Arbuscular Mycorrhyzae)  ECM (Ectomycorrhyzae)  Ectendomycorrhyzae  Ericoid mycorrhyzae  Orchid mycorrhyzae

24. Endo- and Ectomycorrhiza  Wide-spread association: Gymnosperms: 100% infected Gymnosperms: 100% infected Dicots: 83% infected Dicots: 83% infected Monocots: 79% infected Monocots: 79% infected  Three parts to mycorrhizal associations: Root Root Fungal structures in close association with the root Fungal structures in close association with the root External mycelium External mycelium

25. Endo- and Ectomycorrhiza  Ectomycorrhizas Fungal tissue largely outside the root Fungal tissue largely outside the root Primarily found in woody species, but also some ferns and monocots Primarily found in woody species, but also some ferns and monocots  Endomycorrhizas Large fraction of the fungal tissue is within the root cortical cells Large fraction of the fungal tissue is within the root cortical cells Frequently occur on herbaceous plants, also some tropical trees Frequently occur on herbaceous plants, also some tropical trees

26. Endo- and Ectomycorrhiza  Vesicular arbuscular mycorrhiza (VAM) Type of endomycorrhiza with specialized structures (vesicles and arbuscules) Type of endomycorrhiza with specialized structures (vesicles and arbuscules) Fungi belong to Glomales (Glomus largest genus) Fungi belong to Glomales (Glomus largest genus) Considered the most ancient type of mycorrhizal symbiosis Considered the most ancient type of mycorrhizal symbiosis Roots of more than 80% of all plant species are infected with VAM-forming fungi Roots of more than 80% of all plant species are infected with VAM-forming fungi

27. Endo- and Ectomycorrhiza  VAM infection process Spores are found in the soil, or fungi may colonize from other plant roots Spores are found in the soil, or fungi may colonize from other plant roots Forms an appressorium only on host plants, colonizes through passage cells of exodermis Forms an appressorium only on host plants, colonizes through passage cells of exodermis Hyphae remain in cortex and don’t penetrate through endodermis to stele Hyphae remain in cortex and don’t penetrate through endodermis to stele  Ecomycorrhiza infection process Form a mantle of fungal hyphae Form a mantle of fungal hyphae Hyphae penetrate intercellular into the cortex, forming Hartig net Hyphae penetrate intercellular into the cortex, forming Hartig net

28. Perbedaan Antara ECM dan VAM Secara Garis Besar ECM (Ectomycorrizae) VAM (Vescicular Arbuscular Mycorrhizae) Umumnya Basidiomycetes Umumnya Endogonales Terdapat pada jenis pohon membentuk Hartig net antara sel-sel cortex Terdapt pada tumbuhan kecil Hyphae masuk langsung ke dalam sel-sel cortex Membentuk mantel yang menyelimuti akar Tidak membentuk mantel Puluhan ribu jenis cendawan Hanya puluhan jenis Hyphae bisa jauh dari akar Hyphae tumbuh dekat akar

29. Figure. Schematic structure of a vesicular-arbuscular mycorrhiza (VAM).

30. ENDOMYCCORHIZA

31. ECTOMYCORRHIZA

32. http://www.irwantoshut.co.cc/