Lab 4

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Lab 4
2015-09-24 10:23:22

Galls lab
Show Answers:

  1. What is hyperplasia?
    It is the abnormal increase in cell division giving rise to galls
  2. What is hypertrophy?
    An abnormal increase in cell size
  3. Describe crown gall
    • Caused by agrobacterium tumefaciens
    • Mostly effect woody, perennial hosts, tree fruits and grapes
    • Grasses are only plant to escape this disease
    • Once infection occurs growth of the galls are independent of the bacterium
  4. Symptoms of crown gall
    • Galls
    • Disrupts nutrient and water flow
  5. What are aerial crown galls?
    Systemic infection of agrobacterium tumefaciens occurs when individual cells break off the gall and travel through the vascular tissue to other parts of the plant
  6. How to control crown gall
    • Rotation with non-host crop
    • Avoid wounding of Plant and control root chewing insects
    • Use disease free plants
    • Active galls can be killed using bacticin
    • A biological control agent called agrocin84 ( contains A. Radiobacter strainK84 dip rootstocks)
  7. What is black knot ?
    • Caused by dibotryon morbosum
    • Infects prunus species
    • Disease is limited to North America
    • Swellings on twigs and branches
  8. How to control black knot?
    • Foliar application of fungicide in the spring
    • Removal and destruction of galls
    • Removal of native or weedy hosts near orchards
  9. What are decay diseases?
    • Disintegration of host tissues are a result of enzymatic activity of pathogen
    • Most common enzyme are cellulases which degrade cellulose
    • Pectinases which degrade pectin
  10. Why does dibotryon morbosum belong to the phylum ascomycota?
    • It makes ascospores in a pseudothecium
    • The pseudothecia are embedded in a dark colored mass of fungal tissue called stroma
  11. What are environmental conditions needed for D. Morbosum?
    • Rain for the release of ascospores
    • Temps 13-25C
  12. Characterize soft rots
    Watery disintegration of plant tissue followed by slimy masses and odors
  13. What are plant pathogenic soft rot pathogens?
    Are bacteria that infect and colonize plant tissue and in the process release extra cellular enzymes that degrade the plant tissue
  14. Describe bacterial soft rot
    • Infection by pectobacterium carotovorum
    • Occurs in the field and post harvest
    • Affects primarily vegetables
  15. How to control bacterial soft rot?
    • In crop:
    • Avoid root wounding
    • Start with healthy seed
    • Post harvest:
    • Sanitation
    • Cold storage
  16. What are gram positive bacteria?
    Bacteria that have a thick peptidoglcan and retain the crystal violet stain
  17. What are gram negative bacteria?
    They have an outer membrane with a thin peptidoglcan layer
  18. What is a perthophyte?
    Fungi that colonize dead tissue
  19. What is white rot?
    Is a wood decay disease characterized by the whitish color of the decayed wood that results from the removal of lignin
  20. What is brown rot?
    The decayed wood is a brownish color due to the removal of cellulose from the wood by the fungus.