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