Lecture 4: Intro to Plant Parasitic Nematodes (4/22)

Question 1

PPNs

What does it mean?

Answer 1

Plant parasitic nematodes

Question 2

How does a PPN infect an organism?

Answer 2

With a stylet (infection organ)

Question 3

Stylet

What does it do?

Answer 3

Breaks down cell walls, penetrates the host
Takes up nutrients
Secretes effector proteins

Question 4

Effector proteins

What do they do?

Answer 4

Modify plant cell structure, suppress defense, or create feeding sites

Question 5

What are the different types of PPNs?

(about lifestyle)

Answer 5

Sedentary endoparasites
Sedentary semi-endoparasites
Migratory endoparasites
Migratory ectoparasites

Question 6

Sedentary endoparasites

Answer 6

Live inside the root for their entire life cycle

Question 7

Sedentary semi-endoparasites

Answer 7

Head and neck inside the root only

Question 8

Migratory endoparasites

Answer 8

Live entirely inside the root and moves around inside it, feeding on individual cells

Question 9

Migratory ectoparasites

Answer 9

Doesn’t enter the root, feeding on individual cells

Question 10

Key differences between animal and plant parasitic nematodes

Answer 10

Plant hosts are stationary, animals move.
PPNs must penetrate tough plant cell walls (vs. animal cell membranes).
Symptoms in plants are harder to detect

Question 11

Plant parasitic nematodes

How many species are known?
What do they feed on?
What special organ do they have?

Answer 11

~4,100 known species
Biotrophic
Have stylets

Biotrophic: feed on living plant tissue

Question 12

Symptoms of PPN Infection

Answer 12

Above-ground: Slow growth, wilting despite moisture, yellow leaves, nutrient deficiencies

Below-ground (roots): Stunting, excessive branching, root tip swellings, lesions

Question 13

Esophageal gland cells

Answer 13

Secrete effector proteins through the stylet
Subventral glands are active during invasion
Dorsal gland is active in feeding/sedentary stages