Biology Reference
In-Depth Information
It has also been shown that a rise in [Ca
2+
]
cyt
induces NO production through
NOS-like enzyme (Lamotte et al.
2004
; Corpas et al.
2006
; Vandelle et al.
2006
).
Ca
2+
-dependent NO production induced by an elicitor in
Arabidopsis thaliana
was
brought about by the activation of the plasma membrane by cyclic nucleotide gated
channel CNGC2 (Ali et al.
2007
). Arabidopsis
dnd1
( d efense n o d eath 1) mutants
without functional CNGC2 lack inward plasma membrane Ca
2+
currents and fail to
produce NO in response to the bacterial elicitor treatment (Ali et al.
2007
). These
results suggest that a complex interaction between NO and Ca
2+
infl ux may exist
and NO increases [Ca
2+
]
cyt,
while [Ca
2+
]
cyt
increases NO production.
It has also been reported that the generated NO can induce cytosolic Ca
2+
increase through activation of plasma membrane- and intracellular membrane-
localized Ca
2+
channels during pathogen induced signaling cascades (Ali et al.
2007
). The bacterial PAMP LPS could elicit NO generation in leaf guard cells and
facilitate Ca
2+
infl ux into the cytosol (Ali et al.
2007
). NO synthesis occurring
during the plant-pathogen interactions causes elevation of cytosolic Ca
2+
level
(Lamotte et al.
2004
,
2006
; Vandelle et al.
2006
; Besson-Bard et al.
2008a
,
b
). It is
suggested that the NO generated downstream Ca
2+
infl ux may diffuse to neighboring
cells and activate new Ca
2+
signals, which may amplify the NO generation process
(Ma et al.
2007
; Ma and Berkowitz
2011
).
6.6
Interplay Between NO and ROS Signaling Systems
H
2
O
2
and NO are known to operate together in several signaling cascades
(Delledonne et al.
2002
; Grennan
2007
; Wang et al.
2010
). Both an oxidative and
a NO burst have been reported to occur prior to activation of the signal cascade
that eventually activates the transcription of defense genes (Zaninotto et al.
2006
).
Potential target of H
2
O
2
in
Arabidopsis
includes glyceraldehyde-3-phosphate
dehydogenase (GAPDH) that is reversibly inhibited by H
2
O
2.
GADPH has a role
in mediating ROS signaling in plants as a target of H
2
O
2.
GADPH is also a target
of NO-mediated S-nitrosylation and is inhibited by NO (Lindermayr et al.
2005
).
Since GADPH has been identifi ed as the protein that interacts with both H
2
O
2
and
NO, it is suggested that it may be the link between these two signaling pathways
(Grennan
2007
). Another direct target of H
2
O
2
action is Met adenosyltransferase,
which is inactivated by H
2
O
2
through reversible and covalent oxidation of a Cys
residue. The same Cys residue is also a target for NO, which similarly causes
enzyme inactivation (Hancock et al.
2006
).
MAPK cascade may be involved in production of both NO and ROS (Asai et al.
2008
). The MEK2 - SIPK/NTF4 cascade activates NOS inducing production of NO
and also activates NADPH oxidase inducing production of ROS (Asai et al.
2008
).
ROS have been shown to infl uence the transcription and activation of a number of
mitogen-activated protein kinases (MAPKs) (Rentel et al.
2004
). The MAPK sig-
naling pathways are also potential targets for NO, which infl uences the activity of
Search WWH ::
Custom Search