The phosphatidylcholine-hydrolysing phospholipase C NPC4 plays a role in response of Arabidopsis roots to salt stress

Abstract

Phosphatidylcholine-hydrolysing phospholipase C, also known as non-specific phospholipase C (NPC), is a new member of the plant phospholipase family that reacts to environmental stresses such as phosphate deficiency and aluminium toxicity, and has a role in root development and brassinolide signalling. Expression of NPC4, one of the six NPC genes in Arabidopsis, was highly induced by NaCl. Maximum expression was observed from 3 h to 6 h after the salt treatment and was dependent on salt concentration. Results of histochemical analysis of PNPC4:GUS plants showed the localization of salt-induced expression in root tips. On the biochemical level, increased NPC enzyme activity, indicated by accumulation of diacylglycerol, was observed as early as after 30 min of salt treatment of Arabidopsis seedlings. Phenotype analysis of NPC4 knockout plants showed increased sensitivity to salinity as compared with wild-type plants. Under salt stress npc4 plants had shorter roots, lower fresh weight, and reduced seed germination. Expression levels of abscisic acid-related genes ABI1, ABI2, RAB18, PP2CA, and SOT12 were substantially reduced in salt-treated npc4 plants. These observations demonstrate a role for NPC4 in the response of Arabidopsis to salt stress.

Aluminum ions alter the function of non-specific phospholipase C through the changes in plasma membrane physical properties

“…Based on these results, 10 mM AlCl 3 was chosen as a working concentration for in situ measurements of NPC activity in following experiments. In contrast to NPC activity in situ in Arabidopsis seedlings under salt stress, 25 here we observed negative effect of Al on DAG production. Thus, the possible influence of Al ions on BODIPY-PC incorporation into the roots of Arabidopsis seedlings exposed to Al treatment was examined by laser scanning confocal microscopy.…”

“…Changes of phospholipase A 2 activity in vitro, 12 phospholipase D (PLD) activity 13,14 and phosphatidylinositol-specific phospholipase C (PI-PLC) activity [15][16][17] after Al treatment were demonstrated. In addition to PI-PLC, non-specific phospholipase C (NPC, PC-PLC in prokaryotes and animals), an enzyme that is able to hydrolyse phosphatidylcholine (PC) instead of phosphatidylinositol 4,5-bisphosphate (PIP 2 ), was characterized in plants 18 in relation with a number of different cell processes or stress condition [18][19][20][21][22][23][24][25][26] including Al stress. 27,28 Studies of the target of Al action in plants have demonstrated that Al binds to the apoplast 29 and changes the properties of the PM.…”

“…Concentration dependence of BODIPY-DAG production in Arabidopsis seedlings treated with Al. NPC activity in Arabidopsis seedlings was measured according to Kocourkov a et al 25 Seven-day-old Arabidopsis seedlings (5 seedlings for each sample) were grown in MS medium, transferred into 1/8 MS medium (pH 4) containing different concentrations in the range 0-100 mM AlCl 3 and 0.66 mg ml ¡1 of fluorescent phosphatidylcholine (BODIPY-PC, D-3771, Invitrogen, USA) and were incubated on an orbital shaker at 23 C for 2 h. Lipids were extracted, separated by high-performance thin layer chromatography and quantified. Identification of the BODIPY-DAG corresponding spot was based on comparison with the BODIPY-DAG standard prepared as described earlier.…”

Identification of Open Stomata1-Interacting Proteins Reveals Interactions with Sucrose Non-fermenting1-Related Protein Kinases2 and with Type 2A Protein Phosphatases That Function in Abscisic Acid Responses

“…Diacylglycerol produced by NPC4 can be converted to phosphatidic acid, which acts as a signaling molecule and is also involved in ABA signaling (Jacob et al, 1999;Testerink and Munnik, 2005;Peters et al, 2010). Analyses of npc4 mutants revealed its role in salt, osmotic stress, and ABA responses (Peters et al, 2010;Kocourková et al, 2011). UGE activity has been implicated to provide UDP-Gal for cell wall and galactolipid biosynthesis (Dörmann and Benning 1998;Rösti et al, 2007).…”

Does diacylglycerol serve as a signaling molecule in plants?

“…In A. thaliana plants subjected to salinity stress, the activity of NPC was increased, promoting the production of DAG by 4-fold. 20 Phosphate starvation of A. thaliana upregulates AtNPC4 and AtNPC5, which is for the accumulation of DAG and the supply of inorganic phosphate; 21,22 Later during phosphate starvation, the PC content is transiently increased, before its rapid decrease which coincides with an increase in DAG content, indicating most of the newly synthesized DAG is derived via the PC/PLC pathway. 23 In tobacco cell cultures, treatment with brassinolide raises the DAG content within 15 min through the elevation of PC/PLC activity in a concentration-dependent manner; at the same time the size of the PA pool is not significantly increased.…”