The first indication of the aluminum (Al) toxicity in plants growing in acidic soils is the cessation of root growth, but the detailed mechanism of Al effect is unknown. Here we examined the impact of Al stress on the activity of non-specific phospholipase C (NPC) in the connection with the processes related to the plasma membrane using fluorescently labeled phosphatidylcholine. We observed a rapid and significant decrease of labeled diacylglycerol (DAG), product of NPC activity, in Arabidopsis seedlings treated with AlCl₃. Interestingly, an application of the membrane fluidizer, benzyl alcohol, restored the level of DAG during Al treatment. Our observations suggest that the activity of NPC is affected by Al-induced changes in plasma membrane physical properties.

• Keywords
• Arabidopsis thaliana, BA, benzyl alcohol, BODIPY, BODIPY, 4, 4-difluoro-4-bora-3a, 4a-diaza-s-indacene, BY-2, Bright Yellow 2, DAG, diacylglycerol, HP-TLC, high-performance thin-layer chromatography, MS, Murashige-Skoog, NPC, non-specific phospholipase C, PA, phosphatidic acid, PC, phosphatidylcholine, PC-PLC, phosphatidylcholine-specific phospholipase C, PI-PLC, phosphatidylinositol-specific phospholipase C, PIP2, phosphatidylinositol 4, 5-bisphosphate, PLD, phospholipase D, PM, plasma membrane., aluminum toxicity, benzyl alcohol, diacylglycerol, membrane fluidity, non-specific phospholipase C,
• MeSH
• Arabidopsis drug effects   enzymology   MeSH
• Benzyl Alcohol pharmacology   MeSH
• Cell Membrane drug effects   metabolism   MeSH
• Diglycerides metabolism   MeSH
• Type C Phospholipases metabolism   MeSH
• Aluminum pharmacology   MeSH
• Ions MeSH
• Plant Roots drug effects   metabolism   MeSH
• Seedlings drug effects   metabolism   MeSH
• Boron Compounds metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 1,2-diacylglycerol MeSH Browser
• 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene MeSH Browser
• Benzyl Alcohol MeSH
• Diglycerides MeSH
• Type C Phospholipases MeSH
• Aluminum MeSH
• Ions MeSH
• Boron Compounds MeSH

Aluminum ions (Al) have been recognized as a major toxic factor for crop production in acidic soils. The first indication of the Al toxicity in plants is the cessation of root growth, but the mechanism of root growth inhibition is largely unknown. Here we examined the impact of Al on the expression, activity, and function of the non-specific phospholipase C4 (NPC4), a plasma membrane-bound isoform of NPC, a member of the plant phospholipase family, in Arabidopsis thaliana. We observed a lower expression of NPC4 using β-glucuronidase assay and a decreased formation of labeled diacylglycerol, product of NPC activity, using fluorescently labeled phosphatidylcholine as a phospholipase substrate in Arabidopsis WT seedlings treated with AlCl3 for 2 h. The effect on in situ NPC activity persisted for longer Al treatment periods (8, 14 h). Interestingly, in seedlings overexpressing NPC4, the Al-mediated NPC-inhibiting effect was alleviated at 14 h. However, in vitro activity and localization of NPC4 were not affected by Al, thus excluding direct inhibition by Al ions or possible translocation of NPC4 as the mechanisms involved in NPC-inhibiting effect. Furthermore, the growth of tobacco pollen tubes rapidly arrested by Al was partially rescued by the overexpression of AtNPC4 while Arabidopsis npc4 knockout lines were found to be more sensitive to Al stress during long-term exposure of Al at low phosphate conditions. Our observations suggest that NPC4 plays a role in both early and long-term responses to Al stress.

• Keywords
• Arabidopsis, aluminum toxicity, diacylglycerol, non-specific phospholipase C, plasma membrane, pollen tube, signaling, tobacco,
• Publication type
• Journal Article MeSH