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17 Cards in this Set

  • Front
  • Back
What types of fastidious bacteria are there?
Xylem-inhabiting and phloem-inhabiting; mostly Gram -
What are characteristics of xylem-inhabiting fastidious bacteria?
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?
Pierce's disease of grape
Citrus variegated chlorosis
What are the symptoms of Pierce's Disease?
Marginal necrosis of leaves
Leaf scorching
Grape clusters shrivel and die
Vine die-back
General decline
What are characteristics of phloem-inhabiting fastidious bacteria?
Have cell membrane and cell wall
No flagella
Most are Gram -
Have rippled cell wall
Transmitted by insect vectors--CAN transmit to progeny
No formal taxonomy
What disease symptoms are caused by phloem-inhabiting bacteria?
Leaf chlorosis
Leaf stunting
Shoot proliferation
Witches' broom
Greening of floral parts
Flowers may be dwarfed
Explain characteristics of Citrus Greening.
Transmitted by psyllids
Pathogen is a phloem-limited bacteria
What are characteristics of Mollicutes?
No cell wall with variable shape
No flagella
Cells contain cytoplasm, ribosomes, strands of nuclear material
Transmitted by leafhoppers
Gram -, no spores, Binary fission and budding
What are general control methods for mollicutes?
Heat treatment
Compare and contrast Fastidious bacteria and Mollicutes.
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.
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?
Spherical to slightly ovoid
Helical and branched no-helical filaments
How do you identify phytoplasmas?
Extraction from host for DNA or nucleic acid characterization
DNA probes, RFLP profiles
What are the vectors of fastidious bacteria and mollicutes?
Xylem-inhabiting--sharpshooters, leafhoppers
Phloem-inhabiting--leafhoppers, psyllids
Why is it harder to control citrus greening compared to canker?
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