title: Salicylic Acid Regulates Pollen Tip Growth through an NPR3/NPR4-Independent Pathway.
abstract: Tip growth is a common strategy for the rapid elongation of cells to forage the environment and/or to target to long-distance destinations. In the model tip growth system of Arabidopsis pollen tubes, several small-molecule hormones regulate their elongation, but how these rapidly diffusing molecules control extremely localized growth remains mysterious. Here we show that the interconvertible salicylic acid (SA) and methylated SA (MeSA), well characterized for their roles in plant defense, oppositely regulate Arabidopsis pollen tip growth with SA being inhibitory and MeSA stimulatory. The effect of SA and MeSA was independent of known NPR3/NPR4 SA receptor-mediated signaling pathways. SA inhibited clathrin-mediated endocytosis in pollen tubes associated with an increased accumulation of less stretchable demethylated pectin in the apical wall, whereas MeSA did the opposite. Furthermore, SA and MeSA alter the apical activation of ROP1 GTPase, a key regulator of tip growth in pollen tubes, in an opposite manner. Interestingly, both MeSA methylesterase and SA methyltransferase, which catalyze the interconversion between SA and MeSA, are localized at the apical region of pollen tubes, indicating of the tip-localized production of SA and MeSA and consistent with their effects on the apical cellular activities. These findings suggest that local generation of a highly diffusible signal can regulate polarized cell growth, providing a novel mechanism of cell polarity control apart from the one involving protein and mRNA polarization.
authors: State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha 410082, China; Department of Botany and Plant Sciences, and Center for Plant Cell Biology, Institute of Integrated Genome Biology University of California, Riverside, CA 92521, USA.
authors: Duoyan
authors: D
authors: Rong
authors: Department of Botany and Plant Sciences, and Center for Plant Cell Biology, Institute of Integrated Genome Biology University of California, Riverside, CA 92521, USA.
authors: Nan
authors: N
authors: Luo
authors: Normandie Univ, UniRouen, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, Institute for Research and Innovation in Biomedicine, Végétal, Agronomie, Sol, et Innovation, 76821 Mont-Saint-Aignan, France.
authors: Jean Claude
authors: JC
authors: Mollet
authors: State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Province Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha 410082, China. Electronic address: xml05@hnu.edu.cn.
authors: Xuanming
authors: X
authors: Liu
authors: Department of Botany and Plant Sciences, and Center for Plant Cell Biology, Institute of Integrated Genome Biology University of California, Riverside, CA 92521, USA. Electronic address: yang@ucr.edu.
authors: Zhenbiao
authors: Z
authors: Yang
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism; D004950:Esterases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism; D010368:Pectins / Q000378:metabolism; D053205:Pollen Tube / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development*; D021381:Protein Transport / Q000187:drug effects; D020156:Salicylic Acid / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D002966:Clathrin; C517740:NPR3 protein, Arabidopsis; C502134:NPR4 protein, Arabidopsis; D010368:Pectins; D008780:Methyltransferases; D004950:Esterases; D019204:GTP-Binding Proteins; C501663:ROP1 protein, Arabidopsis; D020156:Salicylic Acid
keywords: CRIB4-GFP; FM4-64; MeSA (methyl salicylic acid); ROP activity; SA (salicylic acid); endocytosis