1. Teleomorph vs Anamorph
The teleomorph (perfect stage) is the sexual stage
The anamorph (imperfect stage) is the asexual stage
Nectria - perithecia
Fusarium - conidia
** Images and lecture material were not entirely created by J. Bond.
Some of this material was created by others.**

2. Remember: most microbes are not pathogens on most plants!
How pathogens attack plants
Apple scab
Southern leaf rust of corn
Remember: most microbes are not pathogens on most plants!

3. Infection Process
Pathogens must gain access into plants to cause disease
Viruses – Wounds
Bacteria – Wounds, natural openings
Fungi and Fungal Like Organisms – Wounds, natural openings, and direct penetration
Nematodes – direct penetration

4. Pathogens use plants for food, but most of the “food” is inside the cell.
To get to this food, pathogens must first penetrate the cell wall.
To penetrate the cell wall, pathogens must first get past the plant cuticle (usually).

5. Regular cell wall
2 layers: cellulose, pectin, hemicelluloses, lignin
Tough to get through
Epidermal cell wall
2 layers plus cutin and wax covering.
VERY tough to get through

6. Mechanical force
Only fungi, nematodes, and parasitic plants use mechanical force to get into the cell
Most use force to get through wax layer (although they must adhere to the wax during penetration)
Adherence is usually by appressoria

7. Appressoria can exert tremendous pressure!
Melanin strengthens fungal cell wall in appressoria and appears to be an important pathogenicity factor
Appressoria also secrete cutinases, cellulases, pectinases
- Once past the cuticle, fungus must continue to secrete cellulases, pectinases,
proteinases to enter each and every cell.

8. Utilization of the protoplast
The protoplast contains the “food” that most pathogens are after
But this food must first be degraded, then absorbed
Degradation by enzymes - amylases, lipases, phospholipases, proteinases