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Interaksi Tumbuhan dengan Bakteri Berguna

Oleh Irda Safni. Interaksi Tumbuhan dengan Bakteri Berguna. Plant Growth Promoting Rhizobacteria (PGPR). Indiscriminate use of chemical fertilizers adversely affects soil microorganism, fertility status of soil and environment.

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Interaksi Tumbuhan dengan Bakteri Berguna

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  1. Oleh Irda Safni Interaksi Tumbuhan dengan Bakteri Berguna

  2. Plant Growth Promoting Rhizobacteria (PGPR) • Indiscriminate use of chemical fertilizers adversely affects soil microorganism, fertility status of soil and environment. • So, PGPRs are replacing agrochemicals for the plant growth promotion. • Economically, environmentally beneficial for lower production cost and for sustainable agriculture.

  3. Plant Growth Promoting Rhizobacteria (PGPR) • Term rhizosphere given by Hiltner (1904) and term PGPR given by Kloepper and Schroth (1981) • Rhizosphere is the narrow zone of soil specifically influenced by the root system • Populated by microorganisms and the bacteria called rhizobacteria • Three types: beneficial, deleterious & neutral groups • Beneficial free-living soil bacteria referred to as PGPR • Bacillus and Pseudomonas spp. are predominant among PGPR

  4. BENTUK PGPR • 1. EXTRACELLULAR PGPR(ePGPR) • In rhizosphere, rhizoplane or between cells of root cortex • Includes Agrobacterium, Arthrobacter, Azotobacter, Azospirillum, Bacillus, Caulobacter, Chromobacterium, Erwinia, Pseudomonas and Serratia Flavobacterium, Micrococcous, • 2. INTRACELLULAR PGPR (iPGPR) • Inside specialized nodular structures of root cells. • Includes Allorhizobium, Bradyrhizobium , Mesorhizobium and Rhizobium, endophytes and Frankia 12/27/2016 6

  5. MEKANISME PGPR • 1.DIRECT MECHANISM • Providing plant with a compound synthesized by bacterium or facilitating uptake of nutrients from the environment • 2. INDIRECT MECHANISM • Reducing or preventing deleterious effects of phytopathogenic organisms by producing antagonistic substances or by inducing resistance

  6. Fig : The possible mode of action used by PGPR towards growth promotion in plants. The flow and location of nitrogen fixation, phosphorus solubilization, and siderophore production are shown (Vacheron, Desbrosses, Bouffaud, Touraine.,2013) MODE OF ACTION OFPGPR 8 12/27/2016

  7. Plant growth promoting rhizobacteria promote plant growth directly and indirectly.

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  9. DIRECTMECHANISMS • 1. NITROGENFIXATION • Twomechanisms:- • SYMBIOTIC NITROGENFIXATION • Mutualistic relationship between a microbe and theplant. • Eg. Rhizobium, Bradyrhizobium, Sinorhizobium, Mesorhizobium andFrankia • NON-SYMBIOTIC NITROGENFIXATION • By free livingdiazotrophs • Eg.Azotobacter, Acetobacter, Azospirillum,Diazotrophicus,Enterobacter,Pseudomonas andcyanobacteria • Providesan integratedapproachfordisease managementandmaintains nitrogen level in soil 9 12/27/2016

  10. 2. PHOSPHATE SOLUBILIZATION • The main P solubilization mechanism includes: • Release of complex or mineral dissolving compounds • Liberation of extracellular enzymes • Release of P during substrate degradation • Includes genera Arthrobacter, Bacillus, Beijerinckia, Enterobacter,Erwinia, Flavobacterium, Microbacterium Pseudomonas, Rhizobium, Rhodococcus, and Serratia.

  11. MOVEMENT OF PHOSPHORUS IN SOIL 11 12/27/2016 Source: Insight Microbiology;volume 1;issue 3,20

  12. P SOLUBILIZATION BY P SOLUBILIZINGBACTERIA Source: Insight Microbiology;volume 1;issue 3, 2011 12 12/27/2016

  13. 3. POTASIUM SOLUBILIZATION • K is the third major essential macronutrient • PGPR solubilize K rock through production and secretion of organic acids. • They release K in accessible form from K • bearing minerals in soils. • Includes genera Acidothiobacillus Bacillus, Ferrooxidans, Bacillus, Burkholderia, Paenibacillus sp., and Pseudomonas 13

  14. 4. SIDEROPHORE PRODUCTION • Siderophores are low moleculare weight iron- chelating compounds which provide a high affinity to coordinate ferric ions. • Kloeppar et al. (1980) were the first to demonstrate the importance of siderophore. • Direct benefit: Take up the labeled iron and chelating scarcely available iron • Indirect benefit: Enhanced chlorophyll level

  15. IMPACT OF MICROBIALLY SECRETED SIDEROPHORES ON PLANTGROWTH Source: Insight Microbiology;volume 1;issue 3, 2011 15

  16. 5. PHYTOHORMONE PRODUCTION • a. Indole Acetic Acid (IAA) • Up to 80% of rhizobacteria can synthesize IAA • IAA stimulate cell proliferation, seed germination, resistance to stressful conditions and enhance uptake of minerals and nutrients • Pseudomonas, Rhizobium, Bradyrhizobium, Agrobacterium, Enterobacter and Klebsiella are IAA-producing PGPR

  17. b. Cytokinin andGibberellins • Includes genera Azotobacter sp., Rhizobium sp., Rhodospirillum rubrum, Pseudomonas fluorescens, Bacillus subtilis etc • Some strains of phytopathogens also synthesize cytokinins • PGPR produce lower cytokinin levels compared to phytopathogens • Thus, effect of PGPR on plant growth is stimulatory while that of pathogens is inhibitory.

  18. c.Ethylene • Lowering of ethylene production by inoculation of PGPR strains induces:- • Improved nodule number • Improved nodule dry weight • Higher grain yield and straw yield • Increased nitrogen • Includes genera: Pseudomonas sp., Achromobacter,Agrobacterium, Azospirillum, Bacillus, Burkholderia, Enterobacter, Ralstonia.

  19. INDIRECTMECHANISMS • 1. ANTIBIOTICS • One of the most powerful bio control mechanisms • Antibiotics produced:- • By Pseudomonads: amphisin, (DAPG), oomycin • A, phenazine, tensin, and cyclic lipopeptides. • By Bacillus, Streptomyces and Stenotrophomonas sp: oligomycin A and xanthobaccin. • Drawback: • Some phytopathogens may specific antibiotics due to increased use.

  20. 2. LYTIC ENZYMES • PGPRs produce enzymes such as chitinases, dehydrogenase, β-glucanase, lipases, phosphatases, proteases etc. exhibiting hyperparasitic activity • Suppression of pathogenic fungi including Botrytis cinerea, Sclerotium rolfsii, Fusarium oxysporum, Phytophthora sp., Rhizoctonia solani, and Pythium ultimum

  21. 2. INDUCED AND SYSTEMIC RESISTANCE (ISR) It is a physiological state of enhanced defensive capacity elicited in response to specific environmental stimuli and consequently the plant’s innate defenses are potentiated against subsequent biotic challenges.

  22. 4. EXO POLYSACCHARIDEPRODUCTION • Functions of EP-producing PGPR:- • Biofilm formation and rootcolonization. • Holding freephosphorous • Circulating essential nutrient to theplant • Protecting from foreign pathogens andstress • Shielding from desiccation • Plant defense response in plant–microbeinteractions

  23. Most terrestrial plants develop their root system to explore soil and find nutrients to sustain growth. • In Fabaceae for example, the root tip help in initiating the rhizobial colonization process. • Poaceae, root hairs and lateral roots are colonized by PGPR.

  24. The search for PGPR and investigation of their modes of action are increasing at a rapid pace as efforts are made to exploit them commercially as biofertilizers. • PGPR help in fixing N2, increasing the availability of nutrients, positively influencing root growth and morphology, and promoting other beneficial plant–microbe symbioses. • The combination of these modes of actions in PGPR is also addressed, and widespread utilization of PGPR as biofertilizers.

  25. BIOCONTROL PROPERTIES OF PGPRS • Bio control: Process through which a living organism limits the growth or propagation of undesired organisms or pathogens • Mechanism:- • Competition for nutrients • Production of antibiotics • Production of enzymes to degrade cell wall • Production of siderophores • Production of metabolites • Displacing pathogens

  26. Stress tolerant crops with minimized production costs and environmental hazards can be by the use of PGP microbes as stress relievers. • Indigenous and native microbes were effective and competitive. • This includes: • Extreme of temperature • Salinity • Soil acidity • Heavy metal resistence

  27. The need of today’s world is high output yield and enhanced production of the crop as well as fertility of soil to get in an ecofriendly manner. • Future research in rhizosphere biology will rely on the development of molecular and biotechnological approaches to increase our knowledge of rhizosphere biology. • Fresh alternatives should be explored for the use of bioinoculants.

  28. The application of multi strain bacterial consortium over single inoculation could be an effective approach for reducing the harmful impact of stress on plant growth. • Research on nitrogen fixation and phosphate solubilization by PGPR is progress on but research done on potassium solubilization is little, will not only increase the field of the inoculants but also create confidence among the farmers for their use. • Higher yield and cost effective PGPR products use by agricultural farmer.

  29. Thank You

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