Molecular and ecological analysis of LOX3- and NPR1-dependent defense responses in plant-herbivore interactions
JA-dependent LOX3 and SA-dependent NPR1 perform vital defense functions in Nicotiana attenuata. LOX3 impose stringent growth responses in insects and NPR1 act as a signalling modulator of plant defenses. We found that JA-dependent LOX3-dependent defense responses/metabolites decrease food digestibility in early-instar larvae which prevent them from consuming more food in the later stages. On the other hand, NPR1 serves as a signal modulator and is vital in determining the outcome of JA-dependent LOX3-dependent defense responses. SA was found to have an inhibitory effect on JA- dependent LOX3-dependent defense responses. Therefore, NPR1 serves as a negative regulator of SA biosynthesis in response to herbivore damage in order to activate the JA pathway, and helps the plant finetune an appropriate defense response to herbivores.