AtNSF regulates leaf serration by modulating intracellular trafficking of PIN1 in Arabidopsis thaliana

In eukaryotes,N-ethylmaleimide-sensitive factor(NSF)is a conserved AAA+ATPase and a key component of the membrane trafficking machinery that promotes the fusion of secretory vesicles with target membranes.Here,we demonstrate that the Arabidopsis thaliana genome contains a single copy of NSF,At NSF,which plays an essential role in the regulation of leaf serration.The At NSF knock-down mutant,atnsf-1,exhibited more serrations in the leaf margin.Moreover,polar localization of the PINFORMED1(PIN1)auxin efflux transporter was diffuse around the margins of atnsf-1 leaves and root growth was inhibited in the atnsf-1 mutant.More PIN1-GFP accumulated in the intracellular compartments of atnsf-1 plants,suggesting that At NSF is required for intracellular trafficking of PIN between the endosome and plasma membrane.Furthermore,the serration phenotype was suppressed in the atnsf-1 pin1-8 double mutant,suggesting that At NSF is required for PIN1-mediated polar auxin transport to regulate leaf serration.The CUPSHAPED COTYLEDON2(CUC2)transcription factor gene is up-regulated in atnsf-1 plants and the cuc2-3 single mutant exhibits smooth leaf margins,demonstrating that At NSF also functions in the CUC2 pathway.Our results reveal that At NSF regulates the PIN1-generated auxin maxima with a CUC2-mediated feedback loop to control leaf serration.