RHIZOSFER Hiltner (1904): bagian dari tanah yg dipengaruhi

langsung oleh akar tnm Yunani:

- Rhiza/Rhizo (akar)

- Sphere (area atau tempat di sekitar akar) Meliputi: ektorhizosfer & endorhizosfer (Torrey &

Tjepkema, 1979) serta rhizoplan (Clark, 1949) Kegiatn mikrobiologi brlangsung lebih kompleks

daripd tmp lain di dlm tanah

Rovira et al. (1979):1. Exudates: low molecular weight compounds (i.e: sugar, amino acid) that leak from intact cells

2. Secretions: compound that are actively realease from root cells

3. Plant mucilage: there are four sources from various parts of the root including

a. Secretion by th golgi bodies of the root cap cells

b. Hydrolysates of the primary cell wall located between the root cap and the epidermis

c. Secretion by epidermal cells and root hairs with primary walls

d. Compound resulting from the microbial degradation and modification of dead epidermal cells

4. Mucigel: gelatinous material on the root surface composed of plant mucilage, bacterial cells, metabolic products, and colloidal organic and mineral material

5. lysates: material release through the lysis of older epidermal cells

Organic compounds detected as root exudates (Curl & Truelove, 1986): Sugar ( glucose, fructose, sucrose, maltose, galaktose, rhamnose, ribose, xylose,

arabinose, raffinose, oligosaccharide Amino compounds (asparagine, ά-alanine, glutamine, leucine/isoleucine, serine,

glycine, cystein/cystine, methionine, phenylalanine, tyrosine, threonine, lysine, proline etc.)

Organic acid (tartaric, oxalic, citric, malic, acetic, propionic, butyric, succinic, fumaric, glycolic, valeric, malonic)

Fatty acid & sterol (palmitic, stearic, oleic, linoleic, linolenic acid, cholesterol,campesterol, stigmasterol, sitosterol)

Growth factor (biotin, thiamine, niacin, pantothenate, choline, inositol, pyridoxine, p-amino benzoic acid, n-methyl nicotinic acid

Nucleotide; favonone; and enzyme (flavonone, adenine, guanine, uridine/cytidine; phosphatase, invertase, amylase, proteinase, polygalacturonase

Miscellaneous (auxin, scopoletin, fluorescent substances, hydrocianic acid, glycoside, saponin, organic phosphorous compounds, nematode cyst or egg hatching factors, nematode attractants, spore and sclerotium germination stimulants and inhibitors, bacterial stimulants and inhibitors, parasitic weed germination stimulators

Kualitas dan kuantitas eksudasi dipengaruhi: Jenis tanaman Media perakaran Fase pertumb/perkembangn tanaman Kerusakan akar dan stress tanaman Faktor lingkungan: suhu; radiasi sinar mth,

kelembaban tanah; status nutrisi tanah Keberadaan mo rhizozfer Aplikasi bhn kimia pd daun (pemupukan;

pestisida dll)

Tabel 3. Wheat rhizosphere population of some major taxonomic and nutritional groups of soil micoorganism as determinated by plate counts

Population Rhizosphere ( log CFU/g )Taxonomic groups

Bacteria 9.08

Actinomycetes 7.66

Fungi 6.08

Protozoa 3.38

Microalga 3.70

Nutritional groups

Gas producing anaerobes 8.70

Ammonifiers 5.59

Anaerobes 7.08

Denitrifiers 8.10

Aerobic cellulose degraders 5.85

Anaerobic cellulose degraders 3.95

Spore formes 5.97

Azotobacter < 3.00

Tabel 2. Distinct microbial types based on ultrastructural morphology and total numbers at different distances from subterranean clover roots (Trifolium subterranium L.) determinated by TEM of ultrathin section

Distance (µm)

Morphologically distinct microbial

typesNumbers ( x109)

0 – 1 8 120

0 – 5 11 96

5 – 10 6 41

10 – 15 3 34

15 – 20 3 13

Pengaruh mo rhizosfer thd tanaman: Meningkatkan pertumb tanaman:

Peningkatan transformasi bhn organik Mobilisasi nutrisi anorganik Produksi substansi pemacu pertumbuhan Aksi antagonisme thd patogen Mikorhiza dll

Mengganggu pertumb tanaman: Penyebab penyakit tanaman Immobilisasi nutrisi Deleterious rhizobacteria

Sejarah PH penyk tnm Atkinson (1892): tdp keragaman keparahn penyakit layu fusarium Potter (1908): tdp penghambatan patogen karena penumpukan hasil

metabolitnya Sanford (1926): pupuk hijau dpt digunakan unt mengatasi penyakit kudis

kentang Millard & Taylor (1927): Streptomyces penyebab kudis kentang dpt

dikendalikan dg S. praecox GB sanford & WC Broadcast (1926): publikasi pertama ttg pengendaliah

hayati jamur penyebab take all pd gandum via PHYTOPATHOLOGY JURNAL (saat pertama penggunaan istilah pengendalian hayati pd penyk tanaman)

R Weindling (1930); publikasi pertama ttg parasitisme Trichoderma viride thd jamur tanah lainnya

Wright (1956): menemukan toksin T. viride yaitu gliotoksin Brian & McGowan (1945): menemukan viridin

Konsep pengendalian hayati1. De Bach (1964) The action of parasites, predators, and pathogens in maintaining another

organism’s population density at a longer average than would occur in their absence

2. Beirner (1967) The control of one organism by another

3. Wilson & huffaker (1976) Penggunaan musuh alamiah (yg diintroduksikan) untuk mengendalikan serangga

hama

4. Cook & Baker (1983) Reduction of amount inoculum or disease producing activity of pathogen

accomplished by or through one or more organism other than man

5. National Academy Sciences (1987) The use of natural or modified organisms, gens or gen products to reduce the

effects of undisirable organisms (pest), and to favor desirable organism such crops, trees, animals, and benefecial insects and microorganisms

PH dlm arti luas (Susanto, 2008): Semua kondisi atau praktik yg berpengaruh thd penurunan

daya tahan atau kegiatan patogen tnm melalui interaksi dg agensia hidup lainnya (selain manusia), yg menghasilkan penurunan keberadaan penyk yg disebabkan patogen

3 klp:1. Pengenalan/pengayaan sp jasad antagonis2. Perubahan konds lingk yg dirancang agar sesuai dg penggandaan atau keaktifan jasad antagonis3. Gabungan kedua cara tsb

PH Hama ≠ PenykHAMA Penekanan pd pengendalian populasi Intensitas serangan hama = f (pop hama)

PENYK. Penekanan pd proses patogenesis via ketiga

komponen disease triangle Intensitas penyakit = f (pat, tnm inang, lingk)

Kelebihan PH

1. Jangka panjang lebih murah2. Relatif bebas resiko dan polusi3. Kompatibel dg Sustainable agriculture system

Kekurangan PH

1. Jangka pendek relatif mahal2. Hasil lambat dan sulit diramalkan3. Terbatas penyebarannya

KOMPONEN PH

IP = f (p, h, e, a, .....)

IP = Intensitas Penyakit p = Pathogen h = Host e = Environment a = Antagonis

DEPAN HOMEPatogen Tnm Inang Antagonis Lingkungan

PATOGEN Konsep PH tgt jenis patogen Serangga ≈ fitonematoda → penurunan pop Gulma ≈ mistletoe → penyakitnya Jamur & bakteri → destruksi & eksklusi inokulum

→ menurunkan/menghilangkan pat stelah infeksi

Patogen dpt bertindak langs dlm mengendalikan penyk → agen PH (pathogen-derived agents)

→ proteksi silang

→ penggunaan strain avirulen

DEPAN Patogen Tnm Inang Antagonis Lingkungan HOME

TANAMAN INANG

Secara langsung → trap crop, decoy crop Sec tdk langsung → berasosiasi dg

antagonis Media ekspresi gen resistensi

DEPAN Patogen Tnm Inang Antagonis Lingkungan HOME

ANTAGONIS orgnisme yg menekan survival atau aktivitas menimbulkan penyk. agen hayati yg berpotensi menekan proses hidup patogen antagonis ≈ musuh alami (entomologi):

jamur (Trichoderma, Pythium, Verticillium, Fusarium dll); bakteri (Agrobacterium, Psudomonas, Erwinia, Bacillus dll); nematoda; virus; viroid; seed plant

mekanisme:

1. Langsung thd patogen: antibiosis; kompetisi; parasitisme; predasi; lisis

2. Tidak langsung : induksi resistensi (ketahanan terimbas)

DEPAN Patogen Tnm Inang Antagonis Lingkungan HOME

Lingkungan (Abiotik) Terlibat sec tdk langsung dlm PH Mempengaruhi tanaman Mempengaruhi mekanisme antagonisme

DEPAN Patogen Tnm Inang Antagonis HOMELingkungan

• Nematode captured by the constricting rings of the predatory fungus Arthrobotrys anchonia

• Mycoparasitism by a Trichoderma strain on the plant pathogen (Pythium) on the surface of pea seed. The Trichoderma strain was stained with an orange fluorescent dye while the Pythium was strained green)

• Scanning electron micrograph of the surface of a hyphae of the plant pathogen Rhizoctonia solani after mycoparasitic Trichoderma hyphae were removed

Mekanisme Antgonisme

1. Kompetisi2. Parasisme/Predasi3. Antibiosis4. ISR (Induced Systemic Resistance) atau SAR

(Systemic Acquired Resistance)

TERIMA KASIH !!!...

DEPAN Patogen Tnm Inang Antagonis Lingkungan HOME