3.2.9 The Role of Aphids in Spreading Plant Viruses Flashcards
Describe the structure of plant viruses
Consist of nucleic acid and protein coat & sometimes outer membrane
How can plant viruses enter plants?
Only through damaged sites or by using vectors
Once inside the plant, what can viruses do (i.e. related to spreading/transmission)?
Can spread throughout plant & can be transmitted to next generation through seeds and vegetative reproductive structures (e.g. tubers)
Name 2 symptoms plant virus diseases
- Yellowing in leaves
- (known as chlorosis)
- Distortion of parts of plant
- e.g. leaf roll, malformation of flower and fruit
What do plant virus diseases do to plants and what does this lead to (economically)?
- Decreases photosynthetic efficiency
- Reduces no. of grains and size of grain = loss of yield
- Decreases value of crops
Describe the lifecycle of an aphid in the spring & summer
- Clone themselves
- Produce genetically identical daughter
- Asexual reproduction
- Half the clones born with wings to migrate to start colonies on a new host plant
Describe the lifecycle of an aphid in the autumn & winter
- Produce males and females to increase genetic variation
- Sexual reproduction
- Need huge stock of embryos that genetically different to increase chance of survival
What does an aphid’s stylet consist of?
Saliva canal and feeding canal
What happens to the stylet as it penetrates the tissues to reach the phloem?
Saliva gels around it
Describe how aphids feed
- Insert their stylet (mouthparts) into phloem
- Phloem vessel is punctured, sap which is under high pressure = forced into aphid’s gut
Name 3 ways how aphids reduce yields of crops
- Remove phloem sap
- Deprives plant of sugars and amino acids
- Encourage growth of moulds on leaves
- Reduces photosynthesis
- Transmitting plant viruses
Why can plant viruses only enter plant cells if they’re damaged?
Plant cell walls are too thick to enter
