The role of nicotine in Nicotiana attenuata

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The role of nicotine in Nicotiana attenuata
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Secondary metabolites

• Compounds produced by a plant that have no direct
  function in growth and development
• no direct function in photosynthesis,
  respiration, solute transport, translocation,
  protein synthesis, nutrient assimilation,
  differentiation, or the formation of
  carbohydrates, proteins, and lipids
• Examples terpenes, alkaloids, hormones
• Many secondary metabolites function as herbivore
  deterrents

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Nicotiana attenuata was studied to determine how
nicotine is related to
herbivore deterrence
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• Jasmonic Acid
• levels increase in response to damage and trigger
  the formation of various secondary metabolites
  the transcription of genes involved in plant
  defense metabolism.

• N. attenuata treated with Jasmonic Acid
• resistance to many herbivores
• increase in nicotine production (2-10 fold)
• decreased mortality rate
• increase in viable seed
• substantial fitness costs when plants were
  growing among competitors in herbivore-free
  environment

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Indirect Defenses

• Herbivore attack causes plant to release green
  leaf volatiles
• Volatile release attracts predatory bugs to eggs
  and feeding larvae
• Volatile release decreases oviposition rates of
  adult moths

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Manduca sexta

• - A nicotine tolerant tobacco
  specialist
• - N. attenuata profoundly alter their
  wound-responses when M. sexta
  larvae attack them
• - A Jasmonic Acid burst and an ethylene burst is
  produced
• -The ethylene burst suppresses the Jasmonic acid
  induced accumulation of nicotine biosynthetic
  genes
• -Ethylene burst does not suppress volatile
  release
• -M. sexta attack down-regulates direct defense
  while up regulating indirect defense

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• After being attacked by M. sexta, N. atennuata
  undergoes a major transcriptional
  re-organization.
• Transcripts involved in photosynthesis were
  down-regulated
• Transcripts responding to stress, wounding, and
  pathogens, and involved in shifting C and N to
  defense were up-regulated
• 8 fatty acid amino acids
• conjugates (FACs) in the
• oral secretions of
• M. sexta are necessary
• and sufficient for
• transcriptional changes,
• the ethylene burst, and
• the volatile release

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