Plant Defenses

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Plant Defenses

• Physical thorns, distasteful, toxic compounds,
  recruiting predatory animals
• ex parasitoid wasps, inject eggs into prey
  (caterpillar) larvae eat caterpillars inside
  out injured plant releases volatile chemicals
  that attract more wasps and warn nearby plants of
  attack

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Beware!Chemical Defenses
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Fig. 39-28
Recruitment of parasitoid wasps that lay their
eggs within caterpillars
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Synthesis and release of volatile attractants
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Chemical in saliva
Wounding
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Signal transduction pathway
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http//www.youtube.com/watch?vsJPUEfjA52Q
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Defense against pathogens

• 1st- physical barriers
• 2nd chemical defenses

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Gene for Gene Recognition

• R genes code for R proteins that recognize
  pathogens proteins
• Leads to a signaling pathway
• Causes an oxygen explosion
• This is a hypersensitive response -

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• Results in death of infected tissue
• Site is sealed off
• Can lead to a systemic
• acquired resistance
• (nonspecific)

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Avirulent minimal damage
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Some plants produce salicylic acid (aspirin)
during a defense response.
aspirin