Virus

Question 1

What is the function of the movement protein (MP) in plant viruses?

Answer 1

The movement protein facilitates the virus’s spread from cell to cell by altering the size exclusion limit of plasmodesmata

Question 2

What is the primary role of the capsid protein in a virus?

Answer 2

The capsid protein, or coat protein (CP), protects the viral genome.

Question 3

What does RNA-dependent RNA polymerase do?

Answer 3

This enzyme replicates the viral genome and transcribes viral mRNA.

Question 4

Why is capping of viral mRNA important?

Answer 4

Capping ensures the efficient translation of the viral mRNA and protects it from the host’s immune system.

Question 5

What is a viroid?

Answer 5

A viroid is a small, circular, single-stranded RNA molecule that is infectious but lacks a protein coat.

Question 6

How many types of viruses are there for example?

Answer 6

several virus types (genera), including Potyvirus, Tobamovirus, and Cucumovirus.

Question 7

What is the difference between a persistent and a semi-persistent virus?

Answer 7

Persistent viruses are acquired by an insect vector and then circulate within the insect’s body, remaining infectious for a long time.

Semi-persistent viruses are also acquired by an insect vector but are retained in the insect’s foregut and can be transmitted for a shorter period.

Question 8

How does a virus move from an insect vector (like an aphid) to a plant?

Answer 8

The virus is carried by the aphid and is transmitted when the aphid feeds on the plant, injecting viral particles into the plant’s cells.

Question 9

Name two viruses that are transmitted by aphids.

Answer 9

Papaya ringspot virus (PRSV) and Zucchini yellow mosaic virus (ZYMV) are both transmitted by aphids (green peach aphids and melon aphids).

Question 10

What virus is transmitted by whiteflies?

Answer 10

Squash vein yellowing virus (SqVYV) is transmitted by whiteflies.

Question 11

How is Tobacco mosaic virus (TMV) transmitted?

Answer 11

TMV is transmitted by bumblebees and through mechanical means.

Question 12

What is the role of the coat protein (CP) in the transgenic papaya story?

Answer 12

The CP gene was the specific gene used to create the transgenic plant. Its expression triggers RNA silencing, which provides the plant with resistance.

Question 13

How does a virus infect a host cell?

Answer 13

A virus infects a host cell by first attaching to it, then entering it, uncoating to release its genome, and finally using the host’s machinery to replicate its genetic material and proteins.

Question 14

What family of viruses do PRSV, ZYMV, and SqVYV belong to?

Answer 14

They all belong to the Potyvirus family.

Question 15

What is the virus type of Cucumber mosaic virus (CMV)?

Answer 15

CMV is a Cucumovirus.

Question 16

What is the function of RNA polymerase in a virus?

Answer 16

RNA polymerase is a viral enzyme responsible for replicating the viral genome and transcribing viral mRNA to produce proteins.

Question 17

What are the two aphid vectors listed for Zucchini yellow mosaic virus (ZYMV)?

Answer 17

The vectors are melon aphids and green peach aphids

Question 18

What is the role of capping in viral infection?

Answer 18

Capping is an essential process that ensures the viral mRNA can be efficiently translated by the host’s ribosomes and is protected from degradation by the host’s immune system.

Question 19

How does a virus go from one cell to another within a plant?

Answer 19

The virus uses a movement protein (MP) to pass through the plasmodesmata, which are channels connecting adjacent plant cells

Question 20

What kind of molecule is a viroid, and what does it lack?

Answer 20

A viroid is a small, single-stranded RNA molecule that lacks a protein coat.

Question 21

What are the three viruses listed that are from the Potyvirus genus?

Answer 21

Papaya ringspot virus (PRSV), Zucchini yellow mosaic virus (ZYMV), and Squash vein yellowing virus (SqVYV).

Question 22

What is the difference between a virus and a viroid in terms of structure?

Answer 22

A virus has a protein coat (capsid) that protects its genome, while a viroid is just a small, infectious RNA molecule with no protein coat.

Question 23

Which viral components are responsible for replication and transcription?

Answer 23

RNA-dependent RNA polymerase is responsible for both the replication of the viral genome and the transcription of viral mRNA.

Question 24

What is the main function of the capsid protein?

Answer 24

The main function is to protect the viral genome.

Question 25

Which virus is transmitted by both insects and mechanical means?

Answer 25

Tobacco mosaic virus (TMV) is transmitted by bumblebees and mechanical means.

Question 26

What is a key difference in transmission vectors between SqVYV and PRSV?

Answer 26

SqVYV is transmitted by whiteflies, while PRSV is transmitted by aphids.

Question 27

How does the movement protein alter plasmodesmata?

Answer 27

It alters the size exclusion limit, allowing the larger viral particles to pass through the channels connecting adjacent plant cells.

Question 28

What are the roles of capsid protein and movement protein in a plant virus?

Answer 28

The capsid protein protects the viral genome, and the movement protein facilitates the spread of the virus from cell to cell within the plant.

Question 29

What is the host range of Tobacco mosaic virus (TMV)?

Answer 29

TMV has an extremely wide host range, infecting over 350 plant species. Its main hosts are tobacco, tomato, pepper, and cucumber.

Question 30

How is TMV transmitted?

Answer 30

TMV is primarily transmitted through mechanical means (like handling plants with contaminated tools or hands) and by bumblebees. It is very stable and can persist in dried plant material and on surfaces.

Question 31

What are the characteristic symptoms of a TMV infection?

Answer 31

Symptoms include a mosaic or mottling pattern on leaves, light and dark green patches, leaf puckering, and stunting.

Question 32

What is the host range of Tomato spotted wilt virus (TSWV)?

Answer 32

TSWV has one of the broadest host ranges of any plant virus, infecting over 1,000 species across more than 90 plant families. Its hosts include tomato, pepper, peanut, lettuce, and ornamentals.

Question 33

How is TSWV transmitted?

Answer 33

TSWV is transmitted in a persistent manner by several species of thrips, primarily the western flower thrips. It cannot be transmitted mechanically.

Question 34

What are the characteristic symptoms of a TSWV infection?

Answer 34

Symptoms include bronzing of leaves, concentric ringspots or necrotic lesions, leaf and stem blight, and stunting.

Question 35

What is the host range of Tomato yellow leaf curl virus (TYLCV)?

Answer 35

TYLCV has a narrow but economically significant host range, mainly affecting tomato, pepper, and other solanaceous crops.

Question 36

How is TYLCV transmitted?

Answer 36

TYLCV is transmitted in a persistent manner by the silverleaf whitefly (Bemisia tabaci).

Question 37

What are the characteristic symptoms of a TYLCV infection?

Answer 37

Symptoms include severe stunting of the plant, upward curling of the leaves, puckering, and a distinct yellowing of the leaf margins.

Question 38

What is the host range of Cucumber mosaic virus (CMV)?

Answer 38

CMV has an exceptionally wide host range, infecting over 1,200 plant species. Its main hosts include cucumber, melon, squash, spinach, banana, and many ornamentals.

Question 39

How is CMV transmitted?

Answer 39

CMV is transmitted in a non-persistent manner by over 80 species of aphids. It can also be transmitted mechanically and by seeds.

Question 40

What are the characteristic symptoms of a CMV infection?

Answer 40

Symptoms include mosaic patterns, mottling, leaf distortion, and severe stunting. Symptoms can vary greatly depending on the host plant.

Question 41

What is the host range of Potato virus Y (PVY)?

Answer 41

PVY primarily infects plants in the Solanaceae family, including potato, tomato, pepper, and tobacco.

Question 42

How is PVY transmitted?

Answer 42

PVY is transmitted in a non-persistent manner by numerous species of aphids. It can also be transmitted mechanically.

Question 43

What are the characteristic symptoms of a PVY infection?

Answer 43

Symptoms in potato can range from mild mosaic to severe necrosis (potato tuber necrotic ringspot disease, PTNRD) and stunting.

Question 44

Which of these viruses are transmitted by aphids?

Answer 44

CMV and PVY are both transmitted by aphids in a non-persistent manner.

Question 45

Which of these viruses are transmitted in a persistent manner?

Answer 45

TSWV (by thrips) and TYLCV (by whiteflies) are transmitted in a persistent manner.

Question 47

Which virus is known for its ability to be transmitted by a non-insect vector, specifically bumblebees?

Answer 47

TMV is known to be transmitted by bumblebees.

Question 48

What is the significance of the wide host range of viruses like TSWV and CMV?

Answer 48

Their wide host ranges make them very difficult to control as they can infect a broad variety of weeds and crops, providing a constant reservoir for the virus and making management challenging.

Question 49

What is a key difference in the type of vectors for these viruses?

Answer 49

The vectors include thrips (TSWV), whiteflies (TYLCV), and aphids (CMV and PVY), in addition to mechanical transmission (TMV). This variety of vectors means different management strategies are needed for each virus.