Plant Virology Flashcards

1
Q

Local lesions

A

A localised area of diseased tissue (chlorotic or necrotic)

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2
Q

Chlorosis

A

Yellowing of leaves

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3
Q

Mosaics

A

Yellow leaves on a green background

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4
Q

Necrosis

A

Tissue death - either by stress or via specific plant-virus interactions

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5
Q

Morphogenetic disturbances

A

Growth reduction, colour deviations, wilting, malformation of specific organs, premature leaf drop or curling

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6
Q

Whiteflies

A

Transmit about 70 serious disease agents - cassava mosaic virus

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7
Q

Aphids

A

65% of viruses with invertebrate vectors are transferred

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8
Q

Nematodes

A

Several wide spread viruses are transmitted via nematodes through soil feeding on root epidermal cells

Viruses can survive within a nematode for up to a year

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9
Q

Fungal vectors

A

wheat mosaic virus carried in the resting spores of fungus - plasmodiophoromycete

Virus can survive for many years

Tobacco necrosis virus - carried on surface of spores - only survive a few hours

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10
Q

Rhizomania

A

Disease of sugar beet caused by virus

Beet necrotic yellow vein virus (BNYVV)

Extensive proliferation of lateral roots - also necrosis of vascular bundles and severe stunting of plants

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11
Q

Mechanical transmission

A

Introduction of virus or viral RNA into a wound made through the plant surface

tobacco mosaic virus (TMV) and potato virus X (PVX) - very succesful viruses - no insect vector

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12
Q

Sexual transmission

A

1/5 of plant viruses are transmitted through seed of infected host

Persist in seed for long periods of time

Seed can become infected via a number of routes including sexual transmission via pollen

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13
Q

TMV

A

First virus to be shown to consist of RNA and protein

First virus to be characterised by X-ray crystallography

First virus to be used for electron microscopy

Replication - once it enters cell through wound site - the virus particles disassemble to expose viral RNA - acts as mRNA immediately to produce the replicase protein

Replicase proteins associate with 3’ end of the +ve sense viral RNA for the production of -ve sense RNA

-ve sense RNA acts as template to produce both full-length genomic +ve sense TNa as well as the +ve sense subgenomic RNAs

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14
Q

Cross protection

A

Mild strains of viruses inoculated onto plants prevent more virulent strains from infecting the plant

Risks include viruses mutating and virus may no longer be mild

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