Inverse relationship between systemic resistance of plants to microorganisms and to insect herbivory.

摘要

It is reported that reducing phenylpropanoid biosynthesis by silencing the expression of phenylalanine ammonia lyase reduces systemic acquired resistance to tobacco mosaic virus [tobacco mosaic tobamovirus], whereas overexpression of phenylalanine ammonia lyase enhances systemic acquired resistance. Tobacco plants with reduced systemic acquired resistance exhibited more effective grazing-induced systemic resistance to larvae of Heliothis virescens, but larval resistance was reduced in plants with elevated phenylpropanoid levels. Furthermore, genetic modification of components involved in phenylpropanoid synthesis revealed an inverse relationship between salicylic acid and jasmonic acid levels. It is concluded that these results demonstrate phenylpropanoid-mediated cross-talk in vivo between microbially- and herbivore-induced pathways of systemic resistance.