title: New insights into the early steps of oil body mobilization during pollen germination.
abstract: In some plants, pollen grains accumulate storage lipids that serve as energy supply during germination. Here, three enzymes involved in early steps of oil body mobilization in the male gametophyte were functionally characterized for the first time. The effect of extracellular sugars on pollen performance and oil body dynamics was also analysed. Olive pollen oil bodies showed phospholipase A, lipase, and lipoxygenase activities on their surface. Enzyme activity levels increased during germination with a maximum after 3h. Removal of extracellular sugars from the germination medium did not affect pollen performance but increased enzyme activity rates and sped up oil body mobilization. Inhibitors seriously hampered pollen germination and pollen tube growth, leading to a characteristic accumulation of oil bodies in the germinative aperture. It can be concluded that storage lipids are sufficient for proper olive pollen germination. A lipase and a lipoxygenase are likely involved in oil body mobilization. Extracellular sugars may modulate their function, while a phospholipase A may promote their access to the storage lipids.
authors.affiliation: Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Zienkiewicz
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Zienkiewicz
authors.forename: Juan David
authors.initials: JD
authors.lastname: Rejón
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Rodríguez-García
authors.forename: Antonio Jesús
authors.initials: AJ
authors.lastname: Castro
mesh_terms: D003470:Culture Media / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018525:Germination / Q000187:drug effects; D008049:Lipase / Q000378:metabolism; D008084:Lipoxygenase / Q000378:metabolism; D031658:Olea / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development*; D010740:Phospholipases / Q000378:metabolism; D010938:Plant Oils / Q000378:metabolism*; D053205:Pollen Tube / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development* / Q000648:ultrastructure; D021381:Protein Transport / Q000187:drug effects; D013194:Staining and Labeling; D013395:Sucrose / Q000494:pharmacology
chemical_list: D003470:Culture Media; D004791:Enzyme Inhibitors; D010938:Plant Oils; D013395:Sucrose; D008084:Lipoxygenase; D010740:Phospholipases; D008049:Lipase