Talking about potatoes, tomatoes, hot peppers, bell peppers (i think), goji berries, etc...
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True, but only in the tobacco varieties, not potatoes and tomatoes. The equivalent to nicotine in the hot peppers is capsaican. It is what makes hot peppers hot. An other equivalent is the deadly poisonous alkaloids of belladonna or mandrake.
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Although the Deadly Nightshade Family (Solanaceae) indeed contains tomatoes, potatoes, peppers, etc., as well as tobacco, only the tobacco plant manufactures nicotine in its tissues as part of its secondary chemistry. (By the way, tobacco plants make nicotine to protect themselves from insect attack, since nicotine is a powerful insecticide -- a poison.)