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Published byAmberly Hampton Modified over 8 years ago
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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)
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Do Now Hornworm Video Plant Defense Notes Corn Smut revisited
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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
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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
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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
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Physical Chemical Indirect
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Trichomes Leaf Toughness/Thickness Lignin Thorns/Spines
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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)
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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
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Neither directly chemically or physically protecting the plant, but still help prevent damage Most involve getting help from other species
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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
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