Plant Path Virology

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Author:
wsucoug12
ID:
309847
Filename:
Plant Path Virology
Updated:
2015-10-23 18:22:03
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Plant Path Virology
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Plant Path Virology
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Plant Path Virology
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  1. List characteristics of Viruses
    • Submicroscopic: nm, Å
    • Infectious
    • Replicate only in living cells
    • They do not divide
    • They do not increase in size
    • They do not reproduce sexually or asexually
    • Intracellular parasite
  2. What causes Tulip mania?
    Cucumber Mosaic Virus
  3. What does Contagium vivum fluidum mean?
    contagious living fluid
  4. What is the Composition of Viruses
    • Nucleic acid:
    • RNA or DNA (but not both)
    • single- or double-stranded (ss or ds), but not both
    • + or – sense (most of them!)
    • nucleic acid core surrounded by a protein coat = virion
    • Protein coat = capsid
    • Composed of subunits= capsomers
  5. Viruses with Divided Genomes
    • Multipartite viruses
    • Bipartite, tripartite, multipartite
    • 2 to 5 particles
    • Why? Stability Genetic variation
  6. What are the shapes of viruses?
    • Rod Shaped: flexuous or rigid
    • Spherical/polyhedral:aka icosahedral, 17-60 nm
    • Baciliform (look like a pill)
  7. How to name plant viruses
    • First host + prominent symptom + virus
    • Tobacco mosaic virus - TMV
  8. Processes in Cell Biology
  9. how to detect plant viruses
    • Observation: Electron microscopy 
    • Virus inclusion bodies
    • Transmission/infectivity(bioassay)
    • Vegetative propagation
    •       →graft transmission, indexing-    conventional grafting, root grafting, Dodder
    • Vector transmission Pollen/seed Mechanical
    • Serology: antibody-antigen reactions, ex ELISA =Enzyme-Linked Immunosorbent Assay
    • Viral nucleic acid via PCR if no protein coat
  10. Methods of Transmission:
    • grafting
    • dodder
    • plant propagules
    •      -true seed and pollen propagation materials
    • soil-inhabiting organismsfungi & nematodes
    • insects and mites
  11. Characteristics of Seed-borne Transmission
    • 1. Seed-transmitted viruses are carried within the embryo. Exception is TMV which is carried on seed surface and probably infects by wounding.
    • 2. Not all virus-infected embryos result in virus-infected seedlings.
    • 3. Seed transmissibility originating from ovule parent depends on the ability of a virus to infect floral parts early in their development.
    • 4. There are three dominant factors controlling occurrence and frequency of seed transmission:- timing of infection- host-virus interaction- environment, particularly temp., can influence frequencies
  12. What are the Implications of Seed Transmission
    • Virus can be introduced into new areas by infected seed
    • Seed certification programs to minimize planting of infected seed
  13. What are the most important vectors of plant viruses?
    • Aphids (160)
    • Leaf- and planthoppers (35)
    • Whiteflies (114): 111 by B. tabaci
    • Thrips (20)
    • Beetles (20)
    • Nematodes (14)
    • Leaf & bud mites (10)
    • Chytrids (6)
  14. Roles of the vector in transmission
    • dissemination
    • inoculation
    • Protection
    • Inoculum build up (some viruses DO replicate in their vectors)
  15. What are the parameters of transmission
    • Acquisition Feeding Time
    • Inoculation Feeding Time
    • Latent Period
    •        viruliferous
    • Persistence
    •         retention between molts
  16. describe Nonpersistent vector transmission:
    • stylet-borne
    • Acq: sec-min
    • Latent: none
    • Inoc: sec-min
    • Pers: min - <4 hrs
    • ability to transmit lost between molts
    • mechanically transmissible
    • mosaic-type diseases
  17. describe Semipersistent vector transmission:
    • Acq: min - hrs
    • Latent: none
    • Inoc: min - hrs
    • Pers: 1- 100 hrs
    • longer feeding=longer transmission
    • ability to transmit lost between molts some mechanically transmissible mosaic- & yellows-type diseases
  18. describe Persistent vector transmission:
    • circulative
    • Acq: min - hrs
    • Latent: hrs - days - wk
    • Inoc: min - hrs
    • Pers: >100 hrs
    • ability to transmit retained between molts
    • not mechanically transmissible
    • yellows-type & leaf-rolling diseases

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