title: Apical F-actin-regulated exocytic targeting of NtPPME1 is essential for construction and rigidity of the pollen tube cell wall.
abstract: In tip-confined growing pollen tubes, delivery of newly synthesized cell wall materials to the rapidly expanding apical surface requires spatial organization and temporal regulation of the apical F-actin filament and exocytosis. In this study, we demonstrate that apical F-actin is essential for the rigidity and construction of the pollen tube cell wall by regulating exocytosis of Nicotiana tabacum pectin methylesterase (NtPPME1). Wortmannin disrupts the spatial organization of apical F-actin in the pollen tube tip and inhibits polar targeting of NtPPME1, which subsequently alters the rigidity and pectic composition of the pollen tube cell wall, finally causing growth arrest of the pollen tube. In addition to mechanistically linking cell wall construction and apical F-actin, wortmannin can be used as a useful tool for studying endomembrane trafficking and cytoskeletal organization in pollen tubes.
authors.affiliation: School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zhuang
authors.forename: Yi
authors.initials: Y
authors.lastname: Cai
authors.forename: Alice Y
authors.initials: AY
authors.lastname: Cheung
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
mesh_terms: D000199:Actins / Q000378:metabolism*; D000730:Androstadienes; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism* / Q000648:ultrastructure; D004705:Endocytosis; D005089:Exocytosis / Q000502:physiology; D005453:Fluorescence; D007150:Immunohistochemistry; D046529:Microscopy, Electron, Transmission; D010940:Plant Proteins / Q000378:metabolism; D053205:Pollen Tube / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D014026:Nicotiana; D000077191:Wortmannin
chemical_list: D000199:Actins; D000730:Androstadienes; D010940:Plant Proteins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D000077191:Wortmannin
keywords: NtPPME1; apical F-actin; cell wall; endocytosis; exocytosis; wortmannin