Biology Reference
In-Depth Information
Phosphatidyl choline
Phospholipase D
Phosphatidic acid (PA)
Pyrophosphatidic
acid
PA kinase
PA phosphorylase
Diacyl glycerol (DAG)
Fig. 8.2
Phospholipase D-mediated phosphatidic acid and diacyl glycerol generation pathway
(Adapted from Sang et al.
2001
; Anthony et al.
2006
)
Laxalt et al. (
2007
) demonstrated that NO is required for the production of the lipid
second messenger PA via the activation of the phospholipase C (PLC) and DAG
kinase pathway. Treatment of tomato cell cultures with the fungal elicitor xylanase
resulted in a rapid NO accumulation (Laxalt et al.
2007
). NO donor S-nitroso N-acetyl
penicillamine (SNAP) treatment induced PA, PIP, and PIP
2
accumulation within 1
min after treatment in cucumber, probably through activation of PLC (Lanteri et al.
2008
). NO triggers PA formation also through PLD activation (Lanteri et al.
2008
).
ROS signaling system is also involved in accumulation of PA (Desikan et al.
2004
; Mittler et al.
2004
). H
2
O
2
induced rapid and transient accumulation of PA in
suspension-cultured rice cells (Yamaguchi et al.
2004
). H
2
O
2
directly induced PLD
in vitro (Yamaguchi et al.
2004
). H
2
O
2
might act upstream of PA and or even
upstream of NO (Laxalt et al.
2007
). There are also reports that H
2
O
2
is required for
NO production (Lum et al.
2002
; de Pinto et al.
2006
).
G proteins may activate PLC and PLD (Munnik et al.
1995
; Ritchie and Gilroy
2000
). Heterotrimeric G protein
-subunit regulates PLD through a motif analogous
to the DRY motif in G-protein-coupled receptors in
Arabidopsis
(Zhao and Wang
2004
). The activated PLD may hydrolyze phospholipids to produce the lipid second
messenger PA (Zhao and Wang
2004
). PLD is regulated by Ca
2+
(Zheng et al.
2000
).
Downstream, Ca
2+
infl ux activates PLC, DAG kinase, and PLD. Ca
2+
activates
NADPH oxidase, which is involved in ROS production (Munnik et al.
1998a
).
α
8.2
Phospholipids in Ca
2+
Signaling System
The phospholipids-derived second messenger IP
3
releases Ca
2+
from intracellular
compartments into the cytosol (Meijer and Munnik
2003
; Lanteri et al.
2008
;
Munnik and Testerink
2009
). A number of Ca
2+
release channels have been found in
the vacuolar membranes. IP
3
releases calcium through an intact intracellular plant
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