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 P(NPC4):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.
Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Plant Roots/metabolism , Sodium Chloride/pharmacology , Type C Phospholipases/metabolism , Abscisic Acid/genetics , Abscisic Acid/metabolism , Arabidopsis/drug effects , Arabidopsis/enzymology , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Arabidopsis Proteins/physiology , Gene Expression Regulation, Plant , Plant Roots/drug effects , Plant Roots/enzymology , Plant Roots/genetics , Plants, Genetically Modified , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction , Sodium Chloride/metabolism , Type C Phospholipases/genetics , Type C Phospholipases/physiologyABSTRACT
⢠Aluminium ions (Al) have been recognized as a major toxic factor for crop production in acidic soils. This study aimed to assess the impact of Al on the activity of phosphatidylcholine-hydrolysing phospholipase C (PC-PLC), a new member of the plant phospholipase family. ⢠We labelled the tobacco cell line BY-2 and pollen tubes with a fluorescent derivative of phosphatidylcholine and assayed for patterns of fluorescently labelled products. Growth of pollen tubes was analysed. ⢠We observed a significant decrease of labelled diacylglycerol (DAG) in cells treated with AlCl(3). Investigation of possible metabolic pathways that control DAG generation and consumption during the response to Al showed that DAG originated from the reaction catalysed by PC-PLC. The growth of pollen tubes was retarded in the presence of Al and this effect was accompanied by the decrease of labelled DAG similar to the case of the BY-2 cell line. The growth of pollen tubes arrested by Al was rescued by externally added DAG. ⢠Our observation strongly supports the role of DAG generated by PC-PLC in the response of tobacco cells to Al.
