1. Phytochrome: regulation of
Cells and cell growth
Seed germination
Embryo and
Seed development
Genes and enzymes
Skotomorphogenesis
Photomorphogenesis
Biotic & Abiotic Environment
Photoreceptors
Long Distance Transport
Water
Phytochrome
Mineral Nutrition
Primary & secondary metabolism
Phytochrome: regulation of
light responses
Respiration
Photosynthesis: light reaction
Photorespiration
Plant life cycle
Photosynthesis: carbon fixation

2. Plant Responses to Herbivores and Pathogens
HORT 301 – Plant Physiology
November 12, 2010
Taiz and Zeiger, Chapters 13 (p ) and 26, Tsuda and Katagira (2010) Curr Plant Biol
Constitutive and induced responses contribute to plant defense against insect herbivores and pathogens
Induced defensive responses are “activated” based on pest/pathogen recognition and/or herbivore activity/infection

3. Constitutive defense – secondary products that are “toxins”/insecticides and physical barriers
Cell wall and waxes

4. Protein denaturation by tannins

5. Herbivore facilitated hydrogen cyanide production

6. Induced plant defense against insects
Wound damage and host insect detection are sensed to initiate plant defensive mechanisms
Insect ingests plant material, fatty acid (plant) conjugated to amino acid (insect) and processed (hydroxylation to C17) in the gut

7. Local and systemic plant defensive responses to herbivory
Herbivore detection stimulates jasmonic acid (JA) biosynthesis and defense

8. Jasmonic acid signaling

9. Host plant systemic acquired insect resistance - JA and peptide hormone systemin

10. Plant and insect tritrophic response
2010

11. Courtesy of Keyan Zhu-Salzman
Tritrophic interaction of herbivores, plants and predatory insects mediates plant defense
Courtesy of Keyan Zhu-Salzman

12. Courtesy of Keyan Zhu-Salzman
Summary of plant responses induced by herbivore attack
Defense gene regulation
Wound signals
(local/systemic)
Volicitin
oral secretion
(Elicitors)
Octadecanoid-
jasmonate
signal
Ethylene
complex
Volatile
attractant
Defense gene
expression
-amylase inhibitors
lectins
proteinase inhibitors
lipoxygenases
Courtesy of Keyan Zhu-Salzman
Courtesy of Keyan Zhu-Salzman

13. Plant defense against pathogens
Constitutive – toxins and barriers functions as barriers to infection
Induced - local and systemic acquired defense
-N gene
N gene
wheat
Courtesy of T. Mengiste

14. Pattern triggered immunity and elicitor triggered immunity
Tsuda & Katagira (2010)

15. Pathogen triggered immunity
Microbe (pathogen)- associated molecular pattern (MAMP) immunity
Courtesy of T. Mengiste

16. Elicitor triggered defensive signaling pathways
Avr and R interaction is a gene for gene recognition interaction

17. Local, systemic and volatile plant defense against pathogens

18. Salicylic acid (SA) causes local resistance and systemic acquired resistance (SAR)

19. Courtesy of Ji-Young Lee
SA and JA induction of plant defensive gene (anti-microbial protein) expression
Courtesy of Ji-Young Lee

20. Rapid systemic signaling occurs in response to wounding
Miller et al. (2009) ScienceSignaling