Salicylic Acid and Phospholipid Signaling - Salicylic Acid: Plant Growth and Development - page 35

Fig. 2 The phospholipid signaling pathway in plants. PLC phospholipase C, PLD phospholipase
D, PIP 2 phosphatidylinositol 4,5-bisphosphate, DAG diacylglycerol, IP 3 inositol 1,4,5-triphos-
phate, InsP 6 inositol hexaphosphate, PA phosphatidic acid, DGPP diacylglycerol pyrophosphate,
PIP Ca 2+ phosphatidylinositol 4-phosphate, calcium, DAGK diacylglycerol kinase, PC

phosphatidylcholine

3.2 Salicylic Acid and Phospholipid Signaling Cascade

SA signaling has been linked to phospholipids and the enzymes involved in their
metabolism. However, despite studies of the signaling in response to plant growth
regulators, there is little information about the relationship of SA with phospho-
lipid signaling.
The involvement of PLC and PLD in the response to SA has been evaluated in
other genera, such as the Brassica napus plant, where the behavior of these
enzymes was investigated in response to treatment with various inducers of sys-
temic resistance. The authors demonstrated that both PLC and PLD (isoforms,
and) were activated rapidly within the first 6 h of treatment with SA. They con-
cluded that these enzymes have differential regulation of their enzymatic activities,
thus generating a fast cellular response to SA (Profotová et al. 2006 ). In a study by
Krinke et al. ( 2007 ) the treatment of cell suspensions of Arabidopsis thaliana
labeled with orthophosphate ( 32 Pi) with SA was accompanied by increased levels
of PIP and PIP 2 .
In other studies, it has been used as a strategy to establish the contribution of
phospholipid enzymes to the cellular responses of several substances that have
inhibitory effect (Toyoda et al. 2000 ). Pharmacological studies using the inhibitors
neomycin and U73122 (PLC inhibitors) in models of plants, such as alfalfa, rice,
seeds, peas and carrot cell suspensions (Yamaguchi et al. 2005 ; Legendre et al. 1993 ;