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Flashcards in Viruses General Deck (16)
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0
Q

Virys symptoms confused with

A
Herbicides
Nutrient deficiencies and toxicities
Genetic mutations of host
Viroids
Phytoplasmas
** alteration of metabolism and positive identification of virus difficult
1
Q

Virus differences

A

Not spores or fruiting bodies like fungi
No bacterial ooze
Nor cultured

2
Q

Virus diagnosis

A

Virus biology: symptoms,transmission
Virus paricles: e microscopy
Virus proteins: serology
Virus nucleic acids: molecular techniques

3
Q

Plant virus diagnosis

A

Transmission
Symptoms
E microscopy
Serological and molecular tests to ID disease

4
Q

Genetic mutation- chimera

A

Presence of one branch with very severe symptoms

Caused by somatic mutation at bud of branch

5
Q

Examples of symptoms

A
Mosaic
Mottle
Vein banding and clearing
Chlorotic and necrotic spots
Rugosity
Leaf rolling and curling
Enations
Leaf distortion
Streaks
Colour breaking
Seed symptoms
Fruit symptoms- mottling,spraining,stem pitting and grooving
6
Q

Plant virus diagnosis

Other things needed

A

Distribution of virus in field
Evidence of spread
Rapidity of spread
Comparison with healthy plants

7
Q

Disease transmission

A

Differentiate from abiotic- nutrient def,env stress,herbicide
Graft onto healthy indiv of same host

8
Q

Simple budding

A

Twig diseased
Bud or bark patch
Healthy indicator with T shape cut or bark patch
Diseased bud/bark put in cut of indicator
New growth of indicator

9
Q

Different methods virus detect

A

Leaf grafting
Approach grafting
Tissue implntation
Tuber core grafting

10
Q

Graft- genetic compatible

Difficulties

A

Keep healthy and test plants apart
Weeks, monts- symptoms of recipient
Doesnt necessarily ID virus

11
Q

Sink and source

A

Sink- where energy is needed

Aource- where energy is created

12
Q

Mechanically transmissible

A

Enter through wound

Phloem limited is difficult

13
Q

Virus size

A

30nm

14
Q

Negative staining

A

Glow discharge TEM grid for hydrophilisation/hydrophobisation
Pipette plant sap on carbon support film- allow absorb
Touch edge with blotting paper to remove droplet
Dont dry completely- washing steps to remove salts
Pipette drop of staining solution- heavy metal salt
Air dry

15
Q

Ultrathin sections

A

Ultramicrotome