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Plant Herbivory Defense Strategies in the Natural World

Explore the importance of herbivory in plant ecosystems, including seed dispersal and plant defenses against herbivores. Dive into topics such as tritrophic interactions, chemical defenses, and behavioral adaptations. Learn about top-down and bottom-up controls in food chains and how plants handle herbivory through resistance and tolerance mechanisms. Discover various plant defense strategies, including physical, chemical, and behavioral adaptations. Uncover the fascinating world of plant-herbivore interactions and defense mechanisms in this informative guide.

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Plant Herbivory Defense Strategies in the Natural World

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  1. Herbivory

  2. Herbivory • Importance? Great! • Affects plant distribution • Escape hypothesis: seed dispersal = escape herbivores Seed shadow

  3. Herbivory Food chain • Why world green? • What controls herbivores? • Top-down control: • Bottom-up control: predators herbivores plants

  4. Food chain Herbivory predators herbivores • Tritrophic interactions: Plants use • Ex, corn releases volatile • Volicitin (saliva) triggers VOC • Parasitic wasp plants

  5. Herbivory • Plant-plant communication • Ex, sagebrush (Artemisia tridentata) & wild tobacco (Nicotiana attenuata) • Damaged sagebrush lvs.

  6. Herbivory • How plants handle herbivory? • 1) Resistance: • 2) Tolerance:

  7. Plant defenses • Physical • Chemical • Behavioral • Crypsis (camouflage/mimicry) • Associational

  8. Plant defenses (Bottom-up) • 1) Physical defenses: • A) pointy things • Spines? • Thorns? • Prickles?

  9. Plant defenses • 1) Physical defenses • B) trichomes (

  10. Plant defenses Shadow Battlecrab: Babylon 5 • 1) Physical defenses • C) sharp cells: astrosclerids

  11. Plant defenses • 2) Chemical defenses • A) organic defenses

  12. Plant defenses • 2) Chemical defenses • A) organic defenses • 1) indigestible carbohydrates (cell walls): cellulose & lignin

  13. -ine! Plant defenses • 2) Chemical defenses • A) organic defenses • 2) toxins: small molecules, low dose • ex: alkaloids • (end -ine): caffeine cocaine coca plant

  14. Plant defenses • 2) Chemical defenses • A) organic defenses • 2) toxins • ex: terpenes & terpenoids.

  15. Plant defenses • 2) Chemical defenses • Ex: terpenes—pyrethroids • monoterpenes (10 carbons) from Chrysanthemum

  16. Plant defenses • 2) Chemical defenses • A) organic defenses • 2) toxins • ex: cyanogenic glycosides: release Found in >2500 plant species!

  17. Plant defenses • 2) Chemical defenses • A) organic defenses • 3) digestibility reducers: large, • Bind proteins: digestive • ex, tannins (polyphenols) phenol

  18. Plant defenses • 2) Chemical defenses • B) elemental defenses: From • Silicon (Si): phytoliths cell walls

  19. Plant defenses • 2) Chemical defenses • B) elemental defenses • Metal hyperaccumulation • Ex: >1,000 ppm dry weight Ni

  20. Boyd in Africa!

  21. Elemental Defense • Senecio coronatus • Ni hyper. (12,100 µg Ni/g) & non-hyper. (680 µg Ni/g) pops. on serpentine Test herbivore?

  22. Elemental Defense • Snails: choice high-Ni/ low-Ni leaf • Mean % damage • Hyperaccumulator: 1.9% • Non-hyperaccumulator: 20% Helix aspersa

  23. Defense against pathogens • Ex, bacterium Xanthomonas campestris • Bioluminescence gene • Streptanthus polygaloides, glowcolony shaw

  24. Defense against pathogens • Inoculate low-Ni S. polygaloides • Growth after 72 hr. Ambient light No light

  25. Defense against pathogens • Inoculate high-Ni S. polygaloides • Growth after 72 hr. Ambient light No light

  26. Plant defenses • 3) Behavioral defenses: phenology

  27. Plant defenses • 3) Behavioral defenses: • shed

  28. Plant defenses • 4) Crypsis: look like Biological version of “where’s waldo?”

  29. Plant defenses • 4) Crypsis: look like • Camouflage: look Urban…

  30. Plant defenses • 4) Camouflage • stone plants (Lithops):

  31. Plant defenses

  32. Plant defenses • 4) Camouflage • stone plants (Lithops): Stone(d) plants

  33. Plant defenses • 4) Crypsis • Mimicry: look Wasp Wasp mimics The Hair Band W.A.S.P.

  34. Plant defenses • 4) Mimicry • Passiflora (passionflower) leaves • Heliconius: Heliconius butterfly

  35. Plant defenses • 4) Mimicry • Passiflora egg mimics:

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