Fastidious Bacteria and Mollicutes
Terms
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- What types of fastidious bacteria are there?
- Xylem-inhabiting and phloem-inhabiting; mostly Gram -
- What are characteristics of xylem-inhabiting fastidious bacteria?
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Have cell membrane and cell wall
No flagella
Most are Gram -
Have rippled cell wall
Require complex nutrient media, slow growing and small colonies
Transmitted by xylem-feeding insects--can't transmit to offspring - What diseases are caused by Xylella fastidiosa?
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Pierce's disease of grape
Citrus variegated chlorosis - What are the symptoms of Pierce's Disease?
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Marginal necrosis of leaves
Leaf scorching
Grape clusters shrivel and die
Vine die-back
General decline - What are characteristics of phloem-inhabiting fastidious bacteria?
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Have cell membrane and cell wall
No flagella
Most are Gram -
Have rippled cell wall
Transmitted by insect vectors--CAN transmit to progeny
Non-culturable
No formal taxonomy - What disease symptoms are caused by phloem-inhabiting bacteria?
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Leaf chlorosis
Leaf stunting
Clubbing
Shoot proliferation
Witches' broom
Greening of floral parts
Flowers may be dwarfed - Explain characteristics of Citrus Greening.
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Transmitted by psyllids
Pathogen is a phloem-limited bacteria - What are characteristics of Mollicutes?
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No cell wall with variable shape
No flagella
Cells contain cytoplasm, ribosomes, strands of nuclear material
Small
Phloem-limited
Transmitted by leafhoppers
Gram -, no spores, Binary fission and budding - What are general control methods for mollicutes?
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Antibiotics
Heat treatment - Compare and contrast Fastidious bacteria and Mollicutes.
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Both are Gram - with no spores and no flagella and reproduce by binary fission and phloem-limited and transmitted by a vector.
Fastidious bacteria have cell walls - What are the types of mollicutes?
- Spiroplasmas and Phytoplasmas
- Compare Spiroplasmas and Phytoplasmas.
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Spiroplasmas have a helical structure, are culturable and have a taxonomy.
Phytoplasmas are pleomorphic, unculturable and taxoonomy unresolved - Compare culturable vs non-culturable.
- Culturable means Koch's postulates are fulfilled
- What is the morphology of Spiroplasmas?
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Pleomorphic
Spherical to slightly ovoid
Helical and branched no-helical filaments - How do you identify phytoplasmas?
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Extraction from host for DNA or nucleic acid characterization
Antisera
DNA probes, RFLP profiles - What are the vectors of fastidious bacteria and mollicutes?
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Xylem-inhabiting--sharpshooters, leafhoppers
Phloem-inhabiting--leafhoppers, psyllids
Mollicutes--leafhoppers - Why is it harder to control citrus greening compared to canker?
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Vector (psyllid) is statewide, small, fast, and larvae live in folds of new growth
ID is difficult--no distinctive symptoms, false positives
Spread before evident symptoms