References

8
Nitric Oxide Involvement in Incompatible
Plant–Pathogen Interactions
Matteo De Stefano, Alberto Ferrarini, Massimo Delledonne
Abstract Most plants resist potential parasite attack using a variety of biochemical responses
that often lead to a localized cell death termed the hypersensitive response, and
include production of antimicrobial compounds, lignin formation, oxidative and nitrosative
burst, and increased expression of genes relatedtopathogenesis.Inthisframework,nitric
oxide (NO) functions together with reactive oxygen species in triggering hypersensitive cell
death, and works independently of such intermediates in the induction of defense-related
genes. In this chapter, we will examine the synthesis of NO and its signaling functions in
the hypersensitive response and in the establishment of systemic acquired resistance.
8.1
Introduction
Nitrogen monoxide or nitric oxide (NO) is a bioactive molecule that exerts
a number of diverse activities in phylogenetically distant species (Beligni
and Lamattina 2001). It is a gaseous free radical with a relatively short halflife,
estimated to be less than 6 s (Bethke et al. 2004). This short half-life
reflects the highly reactive nature of NO. Its broad chemistry involves an
interplay between three species differing in their physical properties and
chemical reactivity: the nitrosonium cation (NO + ), the radical (NO • )and
the nitroxyl anion (NO − ) (Neill et al. 2003). Typically, NO rapidly reacts
with reactive oxygen species (ROS), proteins, especially with reactive amino
acids such as cysteine and tyrosine, as well as with various receptors and
transcription factors (Romero-Puertas et al. 2004). NO was first described in
mammals as a major messenger in neurotransmission and is also involved
in vascular smooth muscle relaxation and regulation of vasoprotection.
Macrophages and other circulating cells produce NO, which mediates their
bactericidal and tumoricidal effects (Delledonne et al. 2003). Research on
NO in plants has gained considerable attention in recent years, and there is
increasing evidence of a role of this molecule in plant growth, development
and defense (Romero-Puertas et al. 2004).
Communication in Plants
F. Baluška, S. Mancuso, D. Volkmann (Eds.)
© Springer-Verlag Berlin Heidelberg 2006