1 Researcheres: Abolfazl Moghadam,Shirin Amirtiemoori Instructor: Dr.Rokhbakhsh 2 Rhizosphere : the rhizospher is the volume of soil surrounding and under the influence of plant roots, and the rhizoplane is the plant root surfaces and strongly adhering soil particles ( Kennedy,2005) Rhizobacteria : Rhizobacteria are rhizospher competent bacteria that aggressively colonize plant roots ; they are able to multiply and colonize all the ecological niches found on the root at all stages of plant growth , in the presense of a competing microflora ( Antoun and Kloepper , 2001) 3 Neutral bacteria Pathogenic bacteria Beneficial bacteria ( PGPR ) Suslow, Kloepper, Schroth, Burr, 1979. Figure 1 Nodules of bacteria soybean root 4 PGPR (Plant growth promoting rhizobacteria) A group of bacteria that can actively colonize plant roots and improve plant grows and yield by direct and indirect mechanisms (Noel et al.,1996) (A) Soybean plant infected with Bradyrhizobium japonicim left, uninfected control plant (right). (B) Legume root with nodules induced by B.japonicum Figure 2 5 Figure 3 Figure 4 (MS medium) Effective Two strain of PGPR icluding B.subtilis GB03 , B.amyloliquefaciens IN937a & the nongrowth-promotin strain E.coli DH5α on growth of A.thaliana. 6 DH5α Refrence ; chhong-min Ryu,mohamed A.Farag,…,2003.,Bacteria volatiles promote growth in Arabidopsis These mechanisms Plays a vital role in the management of plant diseases to increase crop productivity via various mechanisms. N2 - fixation Phosphate solublization Direct Siderophore Phytohormones Siderophore Indirect Antibiotic & Antifungal 7 Figure 4 N2 Fixation cycle 8 Using growth medium with Tricalcium phosphate (NBRIP). Bacterial mechanisms: phosphatase enzymes or production of acids Figure 5 Figure 6 Solubilization of P No solubilization 9 Figure 7 Siderophore 10 Figure 8 type of phytohormone produced by PGPR 11 Antibiotic encompass a chemically heterogeneous group of organic,low-molecular weight compounds produced by microorganisms at low concentrations that are deleterious to the growth of metabolic activities of other microorganisms (Fravel,1988;Thomashow et al.,1997). Antibiotics produced by different PGPR have a broad-spectrum activity. 12 PGPR Acinetobacter Agrobacterium Arthrobacter Azospirillum Bacillus Bradyrhizobium Detailes Gram-negative bacilli Gram-negative bacilli Gram-positive , rods during exponential growth and cocci in their stationary phase. Gram-negative bacilli Gram-Positive , rod-shaped Gram-negative bacilli Frankia Pseudomonas Rhizobium Serratia Thiobacillus Gram-Positive , filamentous bacteria Gram-negative bacilli Gram-negative bacilli Gram-negative , rod-shaped Gram-negative , rod-shaped 13 Figure 9 PGPR Antibiotic structure Fungus Gaeumannomyces graminis var.tritici Disease Strains of P.fluorescens may be involved in the suppression of G.graminis var. tritici. In pythium contaminated sites, and signficant increases were observed in plant height,number of heads and grain yield of winter wheat. Reference Raaijmakers & Weller , 2000 P.fluorescens Phenazines P.fluorescens Pyoluteorin Pythium sp. Weller and Cook,1986 P.fluorescens 2,4-Diacetyl phloroglucinol Rhizoctonia solani Out of 40 strains, 18 strains showed strong antifungal activity. Kumar et al.,2002 14 One of the most effective mechanisms that PGPR employ to prevent proliferation of phytopathogens is the systhesis of antibiotic. some well know PGPR strains are pseudomonas,Bacillus, Azospirillum,Rhizobium,and serratia species.the primary mechanism of biocontrol by PGPR involves the production of antibiotics such as phenazine-1-carboxyclic acid, 2,4-diacetyl phloroglucinol, oomycin, pyoluteorin, pyrrolnitrin, kanosamine, zwittermycin-A, and pantocin. 15 Antibiotics DAPG Aerugine Phenazine PCA Pyrrolnitrin Viscosinam ide Pyoluteorin PGPR Pseudomonas sp. P,fluorescens Pseudomonas sp. P.fluorescens Burkholderia cepacia P.Fluorescens P.fluorescens Pathogen Pythium ultimum Phytophthor C.orbiculare Fusarium oxysporwn G.g.Var.tritici Crop sugar Pepper Cucumber tomato Wheat Potato Sugar beet Cotton Sugarbeet Reference Shanahan et al.(1992b) Lee et al.(2003) Lee et at.(2003) Chin-A-Woeng et al.(1998) Thomashow and Weller(1988) Burkhead et al.(1994) Nielsen et al.(1998) Howell and Stipanovic(1980) 16 Fusarium sambucinum Rhizoctonia Solani Pythium ultimum Pythium spp Pythium spp Gaeumannomyces graminis Var. tritici Primary site of Action pyrrolnitrin is terminal electron transport system. Figure 11Structure of pyrrolnitrin Figure 10 Mechanism of Antibiotic Pyrrolnitrin Refrence : R. K. TRIPATHI AND DAVID GOTTLIEB , July 1969, Mechanism of Action of the Antifungal Antibiotic Pyrrolnitrin 17 Figure 11 Mechanism of action of Antibiotic Phenazines Refrence: Latifi, A. M., Winson, K., Foglino, M., Bycroft, B. W., Stewart, G. S. A. B., Lazdunski, A. and Williams, P., Multiple homologues of LuxR and LuxI control expression of virulence determinants and secondary metabolites through quorum sensing in Pseudomonas aeruginosa PA01. Mol. Microbiol., 1995, 17, 333–343. 18 19 Biofertilizer : living organism which increase the nutrient status of the host plant through their ongoing existence in associantion with the plant.( J. Kevin Vessey, 2003) 20 Puts acid in the soil Strengthens pestecides(they become stronger and more resistant to chemicals that should keep them away) It has very little carbon which is a key element in plants Chemical fertilizer also get a lot of water out of the soil which it contaminated and therfor pollute water It degrades ecosytems It releases a green house gas called nitrous oxide 21 Increase soil fertility Product increased to 20-30% Stimulate plant growth Stimulate soil biological activity Protection against dryness and some pathogenic factors of soil Coping with Nature Reduce costs chemical fertilizers, especially nitrogen and phosphorus fertilizer. Improve soil structure 22 Figure 12 difference effect chemical fertilizer with biofertilizer in plant growth 23 Bacterial biofertilizer (Azospirillum , …) Fungi biofertilizer ( Mycorhiza,…) Algae biofertilizer ( blue-green algae,….) Actinomycets (frankia,…) 24 Pseudomonas fluorescence bacteria effectively control wilts and root rot diseases of Groundnut, Cotton, Banana, Soybean, Tomato, Pigeon pea etc., It also controls the rice blast and sheath blight of Paddy. This bacterium enters the plant system and act as a systemic biocontrol agent against diseases. Suitable for: It is suitable for all kinds of Crops. Mode of action: By secreting an enzyme, it has the capability to destroy the cell wall of the fungal pathogens and annihilate them. It secrets Hydrogen cyanide and antibiotics such as Pycocyanin and Phenazine, which inhibit the growth of disease causing pathogens. Advantage: It also produces Siderospores which chelate with iron in the soil, and make it difficult for the pathogens to proliferate. Further, it secretes several plant growth substances, and these gibberellins like compounds contribute to vigorous crop growth. 25 Bacillus subtilis is an antagonistic bacterial Biocontrol agent, which controls many soil and air borne diseases of Paddy, Groundnut, Cotton, Vegetables, Soybean etc., Foliar application of Bacillus subtilis with Pseudomonas fluorescence control leaf diseases of many crops. Suitable for: Paddy, Millets, Oilseeds, Fruits & Vegetables, Sugarcane, Banana, Coconut, Oil palm, Cotton, Chilly, Lime, Coffee & Tea, Areca nut & Rubber, Flower, Spices, & Contiments, Herbs, Lawns & Ornaments, trees etc. Mode of action: The bacterium colonizes the developing leaf & root system of the plant and thus competes with & thereby suppresses plant diseases. Advantage: The Plant Growth Promoting Rhizobacteria (PGPR) having an antagonistic interaction with various soil borne plant pathogens. It protects plants against seed and root diseases. 26 27 PGPR are indigenouse to soil and plant rhizosphere that improve plant growth and yeild. one of the important applications of PGPR to use in biological combating with pathogenic agents . Some of important PGPR Rhizobacteria is Pseudomonas , Bacillus , Rhizobium , Azospirilium and … Important Antibiotic produced by PGPR include Pyrrolnitrin , Phenanzine , 2,4Diacetyl phloroglucinol , oomycin and … That PGPR have important role in biocontrol of plant pathogens and are used in biofertilizers. 28 29