BIOL 458 Study Guide - Quiz Guide: Cytochrome P450, Vindoline, Bombyx Mori
3 Apr 2020
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Document Summary
Plant alkaloids offer protection against herbivory by generalist insects, primarily due to the toxicity of the compounds. Nicotine in tobacco plants has been shown to reduce herbivory by caterpillars. The highly toxic compounds bind and stimulate cholinergic synapses in mammals and insects. Rnai-mediated suppression of putrescine methyltransferase lead to a reduction of constitutive and induced nicotine levels. The lower levels of nicotine lead to faster growth of the caterpillars as they were consuming leaves which do not have negative effects. In a similar manner, nicotine in nectar prevents overconsumption by pollinator insects and promotes shorter feeding times. Madagascar periwinkle synthesizes the components of vinca indole alkaloids in different plant compartments. Catharanthine in synthesized in the leaf wax outside of the leaf epidermis and vindoline is produced in leaf cells. Catharanthine is toxic to silk worm larvae and to pathogenic fungi. The pyrrolizidine alkaloid senecionine-n-oxide in senescio is extremely toxic to mammals and generalist insects.
