Nitric Oxide Signaling during the Hypersensitive Disease Resistance Response.

Nitric oxide (NO) signaling is known to play a key role in triggering the hypersensitive response (HR) of plants to avirulent pathogens. In this chapter, we have summarized what is currently known about the role of NO in this important biological context. We have discussed NO production and turnover leading to the accumulation of this reactive compound when plants are challenged by pathogens. Unfortunately, enzymatic system for its production and the molecular basis for its accumulation are still largely unknown. Furthermore, we have reviewed the ways by which NO transduces its activity to establish hypersensitive disease resistance response by discussing novel emerging findings about its functions. By considering characterized NO targets, we have shown that NO signaling mainly relies on its reactivity with diverse protein targets. This finally orchestrates the crosstalk of NO with other signaling pathways and modulates defence gene expression, allowing the execution of HR cell death and the triggering of the defence response.