title: γ-Aminobutyric acid (GABA) homeostasis regulates pollen germination and polarized growth in Picea wilsonii.
abstract: γ-Aminobutyric acid (GABA) is a four-carbon non-protein amino acid found in a wide range of organisms. Recently, GABA accumulation has been shown to play a role in the stress response and cell growth in angiosperms. However, the effect of GABA deficiency on pollen tube development remains unclear. Here, we demonstrated that specific concentrations of exogenous GABA stimulated pollen tube growth in Picea wilsonii, while an overdose suppressed pollen tube elongation. The germination percentage of pollen grains and morphological variations in pollen tubes responded in a dose-dependent manner to treatment with 3-mercaptopropionic acid (3-MP), a glutamate decarboxylase inhibitor, while the inhibitory effects could be recovered in calcium-containing medium supplemented with GABA. Using immunofluorescence labeling, we found that the actin cables were disorganized in 3-MP treated cells, followed by the transition of endo/exocytosis activating sites from the apex to the whole tube shank. In addition, variations in the deposition of cell wall components were detected upon labeling with JIM5, JIM7, and aniline blue. Our results demonstrated that calcium-dependent GABA signaling regulates pollen germination and polarized tube growth in P. wilsonii by affecting actin filament patterns, vesicle trafficking, and the configuration and distribution of cell wall components.
authors.affiliation: College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ling
authors.forename: Tong
authors.initials: T
authors.lastname: Chen
authors.forename: Yanping
authors.initials: Y
authors.lastname: Jing
authors.forename: Lusheng
authors.initials: L
authors.lastname: Fan
authors.forename: Yinglang
authors.initials: Y
authors.lastname: Wan
authors.forename: Jinxing
authors.initials: J
authors.lastname: Lin
mesh_terms: D015097:3-Mercaptopropionic Acid / Q000494:pharmacology; D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000187:drug effects / Q000378:metabolism; D005453:Fluorescence; D018525:Germination / Q000187:drug effects*; D006706:Homeostasis / Q000187:drug effects*; D028222:Picea / Q000187:drug effects* / Q000254:growth & development*; D011058:Pollen / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development*; D053205:Pollen Tube / Q000187:drug effects / Q000254:growth & development; D011726:Pyridinium Compounds / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
chemical_list: D000199:Actins; C092350:FM 4-64; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D005680:gamma-Aminobutyric Acid; D015097:3-Mercaptopropionic Acid; D002118:Calcium
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