Molecular mechanisms involved in induced resistance signaling in Arabidopsis

Evolution has provided plants with sophisticated defensive strategies \nto "perceive" attack by pathogens and insects, and to translate that \n"perception" into an appropriate adaptive response. Plant innate \nimmunity is based on a surprisingly complex response that is highly \nflexible in its capacity to recognize and respond to the invader \nencountered. In the past years, we explored Arabidopsis as a model to \nstudy the molecular basis of rhizobacteria-induced systemic resistance \n(ISR). We discovered novel components of the ISR signaling pathway \nand revealed that priming for augmented expression of pathogenresponsive \ngenes plays an important role in this type of induced \nresistance. Currently our research is also focused on the question: how \nare plants capable of integrating microbial- and insect-induced signals \ninto defense responses that are specifically directed against the attacker? \nThe alarm signals salicylic acid (SA), jasmonic acid (JA) and ethylene \n(ET) are major regulators of plant defense. Their signaling pathways \ncross-communicate, providing the plant with a regulatory potential to \nfine-tune its defense reaction. We discovered that the regulatory protein \nNPR1 functions as a modulator in cross-talk between SA and JA, \nthereby helping the plant to "decide" which defensive strategy to follow, \ndepending on the type of attacker encountered, and that this function of NPR1 is conserved among Arabidopsis accessions all over the world, \nsuggesting an importany role for plant survival.