Lecture 6: Introduction to Cyst Nematodes

Question 1

Cyst nematodes

1. What kind of parasite are they?
2. J2 length
3. Width
4. Stylet length
5. What do they do?

Answer 1

1. Sedentary endoparasites
2. 350-600 µm length
3. 20-25 µm width
4. 22-26 µm stylet length
5. Form a syncytium, a specialized feeding site

Question 2

Are cyst nematodes obligate biotrophs? Do they have a narrow or broad host range?

Answer 2

Yes, they are obligate biotrophs
They have a narrow host range

Question 3

Symptoms of cyst nematodes

Answer 3

Stunting, chlorosis, wilting, patchy growth

Question 4

What does a synctium do and how is it formed?

Answer 4

Functions as a special nutrient sink for the nematode

A syncytium is formed by dissolving cell walls between adjacent host cells; it is fused plant cells

Question 5

Life cycle of cyst nematodes

of J2s

Answer 5

Eggs hatch into J2 in response to host root exudates
J2s invade roots and secrete effector proteins to establish a syncytium

Question 6

Reproduction of cyst nematodes: sexual or asexual?

Answer 6

Sexual

Question 7

Difference between male and female cyst nematodes

Behavior and size

Answer 7

Females remain sedentary in root, males exit the root after maturing and travel to fertilize females

Females much larger than males

There aren’t any genes that determine gender, whether they turn into females/males generally depends on available nutrition

Question 8

What happens to female nematodes after reproduction?

Answer 8

Their body hardens into a cyst and protects the eggs

Question 9

What is special about a synctium?

Answer 9

Large amounts of unusual sugars and amino acids to support nematode growth and reproduction over weeks

Question 10

Characteristics of cysts

Answer 10

Extremely durable and can survive in soil for years to decades