Please Do Now: If you were a plant, what do you think you would do to defend yourself against animals that want to eat you? (Remember, you can’t move)

 Do Now  Hornworm Video  Plant Defense Notes  Corn Smut revisited

 Herbivory is animals eating plant tissues.  Obviously this is really bad for the plant involved.  Extremely common too, since almost all the energy in the entire food chain comes from plants that have photosynthesized

 Insect pests are the biggest threat to most plants, they do most of the eating  Over the millions of years they have lived together, plants have evolved adaptations to help them protect themselves

 Plant defenses against herbivores can be both inducible and constitutive  Constitutive = always present  Inducible = produced when attack detected This saves resources so they don’t waste them on defenses when there is no threat

 Physical  Chemical  Indirect

 Trichomes  Leaf Toughness/Thickness  Lignin  Thorns/Spines

 Chemicals produced by the plant that damage the herbivore when they eat the plant (basically poison)  Are secondary metabolites (since they are not involved in normal growth/development)

 Phenolics: interfere with plants digesting that they eat Ex: tannins in Oak leaves  Alkaloids: mess up biochemical reactions in the insect, like nerve signaling Ex: caffeine, nicotine, cocaine  Cyanogenic compounds: chemicals, that break down when eaten to produce cyanide, a very strong poison onions

 Neither directly chemically or physically protecting the plant, but still help prevent damage  Most involve getting help from other species

 Releases VOCs to attract parasites of the attackers  Plants make structure for ants to live in or give them sugars in exchange for protection  Fungi that live inside leaves and produce poisons in exchange for sugar