Phospholipase A2 is required for PIN-FORMED protein trafficking to the plasma membrane in the Arabidopsis Root
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Journal. Plant Cell 22(6):1812-1825.
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Abstract
Phospholipase A2 (PLA2), which hydrolyzes a fatty acyl chain of membrane phospholipids, has been implicated in several biological processes in plants. However, its role in intracellular trafficking in plants has yet to be studied. Here, using pharmacological and genetic approaches, the root hair bioassay system, and PIN-FORMED (PIN) auxin efflux transporters as molecular markers, we demonstrate that plant PLA2s are required for PIN protein trafficking to the plasma membrane (PM) in the Arabidopsis thaliana root. PLA2α, a PLA2 isoform, colocalized with the Golgi marker. Impairments of PLA2 function by PLA2α mutation, PLA2-RNA interference (RNAi), or PLA2 inhibitor treatments significantly disrupted the PM localization of PINs, causing internal PIN compartments to form. Conversely, supplementation with lysophosphatidylethanolamine (the PLA2 hydrolytic product) restored the PM localization of PINs in the pla2α mutant and the ONO-RS-082–treated seedling. Suppression of PLA2 activity by the inhibitor promoted accumulation of trans-Golgi network vesicles. Root hair–specific PIN overexpression (PINox) lines grew very short root hairs, most likely due to reduced auxin levels in root hair cells, but PLA2 inhibitor treatments, PLA2α mutation, or PLA2-RNAi restored the root hair growth of PINox lines by disrupting the PM localization of PINs, thus reducing auxin efflux. These results suggest that PLA2, likely acting in Golgi-related compartments, modulates the trafficking of PIN proteins.
Phospholipase A2 (PLA2), which hydrolyzes a fatty acyl chain of membrane phospholipids, has been implicated in several biological processes in plants. However, its role in intracellular trafficking in plants has yet to be studied. Here, using pharmacological and genetic approaches, the root hair bioassay system, and PIN-FORMED (PIN) auxin efflux transporters as molecular markers, we demonstrate that plant PLA2s are required for PIN protein trafficking to the plasma membrane (PM) in the Arabidopsis thaliana root. PLA2α, a PLA2 isoform, colocalized with the Golgi marker. Impairments of PLA2 function by PLA2α mutation, PLA2-RNA interference (RNAi), or PLA2 inhibitor treatments significantly disrupted the PM localization of PINs, causing internal PIN compartments to form. Conversely, supplementation with lysophosphatidylethanolamine (the PLA2 hydrolytic product) restored the PM localization of PINs in the pla2α mutant and the ONO-RS-082–treated seedling. Suppression of PLA2 activity by the inhibitor promoted accumulation of trans-Golgi network vesicles. Root hair–specific PIN overexpression (PINox) lines grew very short root hairs, most likely due to reduced auxin levels in root hair cells, but PLA2 inhibitor treatments, PLA2α mutation, or PLA2-RNAi restored the root hair growth of PINox lines by disrupting the PM localization of PINs, thus reducing auxin efflux. These results suggest that PLA2, likely acting in Golgi-related compartments, modulates the trafficking of PIN proteins.