Bacterial Plant Pathogens

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Bacterial Plant Pathogens

• What are bacteria?
• Bacterial identification
• Generalized disease cycle
• Disease symptoms
• Disease control

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Bacterial Plant Pathogens
Size (0.3-1.5 x 0.7-5 um )
Generally single celled
Reproduce by simple fission
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Prokaryotes
No membrane bound nucleus or organelles
Single circular chromosome
Lack chlorophyll
Most have cell wall
Some are motile flagellum (a)
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Identification
Structure cell shape colony appearance motility
(flagella)
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Identification
Biochemical cell wall composition
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Identification
Respiration aerobic, anaerobic, facultative
anaerobic
Nutritional requirement (C, N, Biolog)
Fatty acids FAME
Serology
Nucleic acids
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Identification
Pathogenicity
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Plant Pathogenic Bacteria (for PLPA3004)

• 8 genera of bacteria, 1 of uncertain ID
• 2 genera of Mollicutes (lack cell walls
• Approximately 50-60 spp. (200 pathovars pv.)
• Pathovar pathogenic on a specific host (crop)

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Plant Pathogenic Bacteria (for PLPA3004)

• Most are facultative parasites,
• Except fastidious bacteria and mollicutes
• Most are gram-, rod-shaped bacteria

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Fastidious vascular bacteria

• Vectored by leafhoppers, except Clavibacter
• Unknown-phloem limited bacterium not culturable
• Symptoms stunting, leaf scalding, decline
• Xylella Pierces disease of grape

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Mollicutes

• Lack cell wall
• Phloem limited
• Transmitted by leafhoppers
• Phytoplasmas amorphous
• Spiroplasmas - helical
• Symptoms yellows diseases, witches brooming,
  stunting
• Sensitive to Tetracycline

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Disease cycle
Overseasoning
2 cycle
o
Reproduction
Dissemination
Disease development
Penetration
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Disease cycle
Protected environment
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Disease cycle

• short distance
• 1.Water
• 2. Soil
• 3. Tools and equipment
• 4. Insects

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Disease cycle
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Disease cycle
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Disease cycle
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Disease cycle
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Disease control
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Disease Control
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Disease Control
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Disease Control
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Symptoms
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Symptoms
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Symptoms