Lecture 5: Migratory Plant-Parasitic Nematodes (4/29)

Question 1

How do nematodes cause damage?

Answer 1

Steal energy
Cause mechanical damage
Physiological disturbance

Nematodes themselves actually don’t require much energy (~1 calorie)
Mechanical damage: harm or defects in roots
Physiological damage: Disturbance of hormonal balance and source sink relationship

Question 2

rDNA

Answer 2

Ribosomal DNA

Question 3

Why is rDNA used?

Answer 3

Conserved and variable regions

Multiple genome copies

Ease of amplification—even from degraded samples

Question 4

How many clades of nematodes are there?

Answer 4

12 clades

Question 5

How many clades did plant parasitism evolve independently in?

Answer 5

At least 4

Question 6

What did PPNs probably evolve from?

Answer 6

Fungivorous ancestors

Question 7

Major PPNs like cyst and root-knot nematodes are in which clade?

Answer 7

Clade 12

Question 8

Onchiostyle

Structure
Hollow?
Found in which clade(s)?
Feeding method

Answer 8

Solid, curved, tooth-like
Solid
Clade 1
Puncture/tear cells, ingest contents

Question 9

Odontostyle

Structure
Hollow?
Found in which clade(s)?
Feeding method

Answer 9

Needle-like
Hollow
Clade 2
Pierce cells, inject enzymes, suck fluids

Question 10

Stomatostyle

Structure
Hollow?
Found in which clade(s)?
Feeding method

Answer 10

Hollow, straight, often spear-like
Hollow
Clades 10-12
Pierce cells, inject enzymes, induces feeding cells

Question 11

What nematode uses an onchiostylet and what kind of crop damage does it cause?

Answer 11

Trichodorus obtusus
Causes stubby root

Question 12

What nematode uses an odontostylet and what kind of crop damage does it cause?

Answer 12

Xiphinema index
Sucks fluids

Question 13

What nematode uses an stomatostylet and what kind of crop damage does it cause?

Answer 13

Meloidogyne, Heterodera
Cause cysts, root knots